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7.6: Effects of Volcanic Eruptions on Humans and on Earth Systems

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• Page ID 25536

• Steven Earle
• Vancover Island University via BCCampus

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Humans have a love-hate relationship with volcanoes. For many reasons humans are attracted to areas with active volcanism, but for several others that we’ve already discussed, they would be wise to stay away.

The key reason that humans like living around potentially active volcanoes is that the soil tends to be fertile, and thus there is the potential to grow enough food to live. For example, some parts of the area around Mt. Merapi in Indonesia (Figure 7.0.1) can support subsistence populations of 8 to 10 people per hectare. [1] In comparison, the typical farm in the United States can feed just under 1 person per hectare ( US Farm Bureau ).

Volcanic soil is good for a number of reasons. One is that volcanic ash and rock fragments are rich in volcanic glass and under weathering conditions glass breaks down quickly to clay minerals so that productive soil can form within 200 to 300 years in favorable climates. [2] Another is that the clays that form from volcanic parent materials are effective at holding onto nutrients such as phosphorous. A third is that volcanic lava or tephra are typically quite rich in some important plant nutrients, such as magnesium and sulphur. Volcanic regions all over the world are know for their fertile soils. Some examples, apart from Indonesia, include the volcanic areas in Italy, much of northern New Zealand, Japan, Hawaii, parts of Africa, and much of the Caribbean.

Volcanoes are also valued for their scenic beauty and recreational opportunities. An example is the Mt. Garibaldi area of southwestern British Columbia (Figure 7.6.1), but there are hundreds of other scenic volcanoes around the world, some of which are immense tourist and hiker attractions (Figure 7.6.2). Many volcanoes are also venues for a wide range of winter sports, and for hot springs, spas and mudbaths. Volcanic regions are also an excellent source of geothermal heat for both electricity and district heating, and of hydroelectric energy from streams.

Many volcanoes are also venues for a wide range of winter sports, and for hot springs, spas and mudbaths. Volcanic regions are also an excellent source of geothermal heat for both electricity and district heating, and of hydroelectric energy from streams. Figure 7.6.3 provides an overview of some of the ways that humans interact with volcanoes, and some of the risks associated with living nearby.

Volcanism and Earth Systems

As already noted in Chapter 1 and Chapter 3 , volcanic eruptions contribute to the Earth’s systems in important ways. For starters, it is widely believed that the water in the Earth’s oceans is at least partly derived from volcanism, and the Earth would not have much in the way of systems without water.

Some of the key roles of volcanic eruptions in Earth systems are as follows:

• Cycling solids (mostly silicates) from depth in the mantle and the crust to surface,
• Cycling volatiles (water and gases) from depth, and thereby influencing organisms and the climate,
• Ejecting both solids and volatiles high into the atmosphere,
• Cycling thermal energy from depth,
• Creating solid surfaces (e.g., islands) that will be colonized by organisms, and
• Creating sloped surfaces (mountains) that influence weather and climate patterns, and will be eroded and weathered.

All of these products subsequently contribute to other Earth system processes in myriad ways.

Media Attributions

• Figure 7.6.1 Photo by Isaac Earle, used with permission, CC BY 4.0
• Figure 7.6.2 Mt. Fuji Summit by Derek Mawhinney, public domain image via Wikimedia Commons, https://commons.wikimedia.org/wiki/F...uji_Summit.jpg
• Figure 7.6.3 Steven Earle, CC BY 4.0
• Dahlgren, R., Saigusa, M., & Ugolini, F. (2004). The nature, properties and management of volcanic soils. Advances in Agronom y, 82 , 114-183. https://doi.org/10.1016/S0065-2113(03)82003-5 ↵
• (Dahlgern et al., 2004) ↵

Essays About Volcanoes: Top 5 Examples and 10 Prompts

Do you need to write essays about volcanoes but don’t know where to start? Check out our top essay examples and prompts to help you write a high- quality essay.

Considered the planet’s geologic architects, volcanoes are responsible for more than 80% of the Earth’s surface . The mountains, craters , and fertile soil from these eruptions give way to the very foundation of life itself, making it possible for humans to survive and thrive.  

Aside from the numerous ocean floor volcanoes, there are 161 active volcanoes in the US . However, these beautiful and unique landforms can instantly turn into a nightmare, like Mt. Tambora in Indonesia, which killed 92,000 people in 1815 .

Various writings are critical to understanding these openings in the Earth’s crust , especially for students studying volcanoes. It can be tricky to write this topic and will require a lot of research to ensure all the information gathered is accurate. 

To help you, read on to see our top essay examples and writing prompts to help you begin writing.

Top 5 Essay Examples

1. short essay on volcanoes by prasad nanda , 2. types of volcanoes by reena a , 3. shield volcano, one of the volcano types by anonymous on gradesfixer.com, 4. benefits and problems caused by volcanoes by anonymous on newyorkessays.com, 5. volcanoes paper by vanessa strickland, 1. volcanoes and their classifications, 2. a dormant volcano’s eruption, 3. volcanic eruptions in the movies, 4. the supervolcano: what is it, 5. the word’s ring of fire, 6. what is a lahar, 7. why does a volcano erupt, 8. my experience with volcanic eruptions, 9. effects of volcanic eruptions, 10. what to do during volcanic disasters.

“The name, “volcano” originates from the name Vulcan, a god of fire in Roman mythology.”

Nanda briefly defines volcanoes, stating they help release hot pressure that builds up deep within the planet. Then, he discusses each volcano classification, including lava and magma’s roles during a volcanic eruption . Besides interesting facts about volcanoes (like the Ojos del Salado as the world’s tallest volcano), Nanda talks about volcanic eruptions ‘ havoc. However, he also lays down their benefits, such as cooled magma turning to rich soil for crop cultivation.

“The size, style, and frequency of eruptions can differ greatly but all these elements are correlated to the shape of a volcano.”

In this essay, Reena identifies the three main types of volcanoes and compares them by shape, eruption style, and magma type and temperature. A shield volcano is a broad, flat domelike volcano with basaltic magma and gentle eruptions . The strato or composite volcano is the most violent because its explosive eruption results in a lava flow, pyroclastic flows, and lahar. Reena shares that a caldera volcano is rare and has sticky and cool lava, but it’s the most dangerous type . To make it easier for the readers to understand her essay, she adds figures describing the process of volcanic eruptions .

“All in all, shield volcanoes are the nicest of the three but don’t be fooled, it can still do damage.”

As the essay’s title suggests, the author focuses on the most prominent type of volcano with shallow slopes – the shield volcano. Countries like Iceland, New Zealand, and the US have this type of volcano, but it’s usually in the oceans, like the Mauna Loa in the Hawaiian Islands. Also, apart from its shape and magma type , a shield volcano has regular but calmer eruptions until water enters its vents.

“Volcanic eruptions bring both positive and negative impacts to man.”

The essay delves into the different conditions of volcanic eruptions , including their effects on a country and its people. Besides destroying crops, animals, and lives, they damage the economy and environment. However, these misfortunes also leave behind treasures, such as fertile soil from ash, minerals like copper, gold, and silver from magma, and clean and unlimited geothermal energy. After these incidents, a place’s historic eruptions also boost its tourism.

“Beautiful and powerful, awe-inspiring and deadly, they are spectacular reminders of the dynamic forces that shape our planet.”

Strickland’s essay centers on volcanic formations, types, and studies, specifically Krakatoa’s eruption in 1883. She explains that when two plates hit each other, the Earth melts rocks into magma and gases, forming a volcano. Strickland also mentions the pros and cons of living near a volcanic island. For example, even though a tsunami is possible, these islands are rich in marine life, giving fishermen a good living.

Are you looking for more topics like this? Check out our round-up of essay topics about nature .

10 Writing Prompts For Essays About Volcanoes

Do you need more inspiration for your essay? See our best essay prompts about volcanoes below:

Identify and discuss the three classifications of volcanoes according to how often they erupt: active, dormant or inactive, and extinct. Find the similarities and differences of each variety and give examples. At the end of your essay, tell your readers which volcano is the most dangerous and why.

Volcanoes that have not erupted for a very long time are considered inactive or dormant, but they can erupt anytime in the future. For this essay, look for an inactive volcano that suddenly woke up after years of sleeping. Then, find the cause of its sudden eruption and add the extent of its damage. To make your piece more interesting, include an interview with people living near dormant volcanoes and share their thoughts on the possibility of them exploding anytime.

Choose an on-screen depiction of how volcanoes work, like the documentary “ Krakatoa: Volcano of Destruction .” Next, briefly summarize the movie, then comment on how realistic the film’s effects, scenes, and dialogues are. Finally, conclude your essay by debating the characters’ decisions to save themselves.

The Volcanic Explosivity Index (VEI) criteria interpret danger based on intensity and magnitude. Explain how this scale recognizes a supervolcano. Talk about the world’s supervolcanoes, which are active, dormant, and extinct. Add the latest report on a supervolcano’s eruption and its destruction.

Identify the 15 countries in the Circum-Pacific belt and explore each territory’s risks to being a part of The Ring of Fire. Explain why it’s called The Ring of Fire and write its importance. You can also discuss the most dangerous volcano within the ring.

If talking about volcanoes as a whole seems too generic, focus on one aspect of it. Lahar is a mixture of water, pyroclastic materials, and rocky debris that rapidly flows down from the slopes of a volcano. First, briefly define a lahar in your essay and focus on how it forms. Then, consider its dangers to living things. You should also add lahar warning signs and the best way to escape it.

Use this prompt to learn and write the entire process of a volcanic eruption . Find out the equipment or operations professionals use to detect magma’s movement inside a volcano to signal that it’s about to blow up. Make your essay informative, and use data from reliable sources and documentaries to ensure you only present correct details.

If you don’t have any personal experience with volcanic eruptions , you can interview someone who does. To ensure you can collect all the critical points you need, create a questionnaire beforehand. Take care to ask about their feelings and thoughts on the situation.

Write about the common effects of volcanic eruptions at the beginning of your essay. Next, focus on discussing its psychological effects on the victims, such as those who have lost loved ones, livelihoods, and properties.

Help your readers prepare for disasters in an informative essay. List what should be done before, during, and after a volcanic eruption . Include relevant tips such as being observant to know where possible emergency shelters are. You can also add any assistance offered by the government to support the victims.Here’s a great tip: Proper grammar is critical for your essays. Grammarly is one of our top grammar checkers. Find out why in this  Grammarly review .

Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (2017)

Chapter: 1 introduction, 1 introduction.

Volcanoes are a key part of the Earth system. Most of Earth’s atmosphere, water, and crust were delivered by volcanoes, and volcanoes continue to recycle earth materials. Volcanic eruptions are common. More than a dozen are usually erupting at any time somewhere on Earth, and close to 100 erupt in any year ( Loughlin et al., 2015 ).

Volcano landforms and eruptive behavior are diverse, reflecting the large number and complexity of interacting processes that govern the generation, storage, ascent, and eruption of magmas. Eruptions are influenced by the tectonic setting, the properties of Earth’s crust, and the history of the volcano. Yet, despite the great variability in the ways volcanoes erupt, eruptions are all governed by a common set of physical and chemical processes. Understanding how volcanoes form, how they erupt, and their consequences requires an understanding of the processes that cause rocks to melt and change composition, how magma is stored in the crust and then rises to the surface, and the interaction of magma with its surroundings. Our understanding of how volcanoes work and their consequences is also shared with the millions of people who visit U.S. volcano national parks each year.

Volcanoes have enormous destructive power. Eruptions can change weather patterns, disrupt climate, and cause widespread human suffering and, in the past, mass extinctions. Globally, volcanic eruptions caused about 80,000 deaths during the 20th century ( Sigurdsson et al., 2015 ). Even modest eruptions, such as the 2010 Eyjafjallajökull eruption in Iceland, have multibillion-dollar global impacts through disruption of air traffic. The 2014 steam explosion at Mount Ontake, Japan, killed 57 people without any magma reaching the surface. Many volcanoes in the United States have the potential for much larger eruptions, such as the 1912 eruption of Katmai, Alaska, the largest volcanic eruption of the 20th century ( Hildreth and Fierstein, 2012 ). The 2008 eruption of the unmonitored Kasatochi volcano, Alaska, distributed volcanic gases over most of the continental United States within a week ( Figure 1.1 ).

Finally, volcanoes are important economically. Volcanic heat provides low-carbon geothermal energy. U.S. generation of geothermal energy accounts for nearly one-quarter of the global capacity ( Bertani, 2015 ). In addition, volcanoes act as magmatic and hydrothermal distilleries that create ore deposits, including gold and copper ores.

Moderate to large volcanic eruptions are infrequent yet high-consequence events. The impact of the largest possible eruption, similar to the super-eruptions at Yellowstone, Wyoming; Long Valley, California; or Valles Caldera, New Mexico, would exceed that of any other terrestrial natural event. Volcanoes pose the greatest natural hazard over time scales of several decades and longer, and at longer time scales they have the potential for global catastrophe ( Figure 1.2 ). While

the continental United States has not suffered a fatal eruption since 1980 at Mount St. Helens, the threat has only increased as more people move into volcanic areas.

Volcanic eruptions evolve over very different temporal and spatial scales than most other natural hazards ( Figure 1.3 ). In particular, many eruptions are preceded by signs of unrest that can serve as warnings, and an eruption itself often persists for an extended period of time. For example, the eruption of Kilauea Volcano in Hawaii has continued since 1983. We also know the locations of many volcanoes and, hence, where most eruptions will occur. For these reasons, the impacts of at least some types of volcanic eruptions should be easier to mitigate than other natural hazards.

Anticipating the largest volcanic eruptions is possible. Magma must rise to Earth’s surface and this movement is usually accompanied by precursors—changes in seismic, deformation, and geochemical signals that can be recorded by ground-based and space-borne instruments. However, depending on the monitoring infrastructure, precursors may present themselves over time scales that range from a few hours (e.g., 2002 Reventador, Ecuador, and 2015 Calbuco, Chile) to decades before eruption (e.g., 1994 Rabaul, Papua New Guinea). Moreover, not all signals of volcanic unrest are immediate precursors to surface eruptions (e.g., currently Long Valley, California, and Campi Flegrei, Italy).

Probabilistic forecasts account for this uncertainty using all potential eruption scenarios and all relevant data. An important consideration is that the historical record is short and biased. The instrumented record is even shorter and, for most volcanoes, spans only the last few decades—a miniscule fraction of their lifetime. Knowledge can be extended qualitatively using field studies of volcanic deposits, historical accounts, and proxy data, such as ice and marine sediment cores and speleothem (cave) records. Yet, these too are biased because they commonly do not record small to moderate eruptions.

Understanding volcanic eruptions requires contributions from a wide range of disciplines and approaches. Geologic studies play a critical role in reconstructing the past eruption history of volcanoes,

especially of the largest events, and in regions with no historical or directly observed eruptions. Geochemical and geophysical techniques are used to study volcano processes at scales ranging from crystals to plumes of volcanic ash. Models reveal essential processes that control volcanic eruptions, and guide data collection. Monitoring provides a wealth of information about the life cycle of volcanoes and vital clues about what kind of eruption is likely and when it may occur.

1.1 OVERVIEW OF THIS REPORT

At the request of managers at the National Aeronautics and Space Administration (NASA), the National Science Foundation, and the U.S. Geological Survey (USGS), the National Academies of Sciences, Engineering, and Medicine established a committee to undertake the following tasks:

• Summarize current understanding of how magma is stored, ascends, and erupts.
• Discuss new disciplinary and interdisciplinary research on volcanic processes and precursors that could lead to forecasts of the type, size, and timing of volcanic eruptions.
• Describe new observations or instrument deployment strategies that could improve quantification of volcanic eruption processes and precursors.
• Identify priority research and observations needed to improve understanding of volcanic eruptions and to inform monitoring and early warning efforts.

The roles of the three agencies in advancing volcano science are summarized in Box 1.1 .

The committee held four meetings, including an international workshop, to gather information, deliberate, and prepare its report. The report is not intended to be a comprehensive review, but rather to provide a broad overview of the topics listed above. Chapter 2 addresses the opportunities for better understanding the storage, ascent, and eruption of magmas. Chapter 3 summarizes the challenges and prospects for forecasting eruptions and their consequences. Chapter 4 highlights repercussions of volcanic eruptions on a host of other Earth systems. Although not explicitly called out in the four tasks, the interactions between volcanoes and other Earth systems affect the consequences of eruptions, and offer opportunities to improve forecasting and obtain new insights into volcanic processes. Chapter 5 summarizes opportunities to strengthen

research in volcano science. Chapter 6 provides overarching conclusions. Supporting material appears in appendixes, including a list of volcano databases (see Appendix A ), a list of workshop participants (see Appendix B ), biographical sketches of the committee members (see Appendix C ), and a list of acronyms and abbreviations (see Appendix D ).

Background information on these topics is summarized in the rest of this chapter.

1.2 VOLCANOES IN THE UNITED STATES

The USGS has identified 169 potentially active volcanoes in the United States and its territories (e.g., Marianas), 55 of which pose a high threat or very high threat ( Ewert et al., 2005 ). Of the total, 84 are monitored by at least one seismometer, and only 3 have gas sensors (as of November 2016). 1 Volcanoes are found in the Cascade mountains, Aleutian arc, Hawaii, and the western interior of the continental United States ( Figure 1.4 ). The geographical extent and eruption hazards of these volcanoes are summarized below.

The Cascade volcanoes extend from Lassen Peak in northern California to Mount Meager in British Columbia. The historical record contains only small- to moderate-sized eruptions, but the geologic record reveals much larger eruptions ( Carey et al., 1995 ; Hildreth, 2007 ). Activity tends to be sporadic ( Figure 1.5 ). For example, nine Cascade eruptions occurred in the 1850s, but none occurred between 1915 and 1980, when Mount St. Helens erupted. Consequently, forecasting eruptions in the Cascades is subject to considerable uncertainty. Over the coming decades, there may be multiple eruptions from several volcanoes or no eruptions at all.

The Aleutian arc extends 2,500 km across the North Pacific and comprises more than 130 active and potentially active volcanoes. Although remote, these volcanoes pose a high risk to overflying aircraft that carry more than 30,000 passengers a day, and are monitored by a combination of ground- and space-based sensors. One or two small to moderate explosive eruptions occur in the Aleutians every year, and very large eruptions occur less frequently. For example, the world’s largest eruption of the 20th century occurred approximately 300 miles from Anchorage, in 1912.

In Hawaii, Kilauea has been erupting largely effusively since 1983, but the location and nature of eruptions can vary dramatically, presenting challenges for disaster preparation. The population at risk from large-volume, rapidly moving lava flows on the flanks of the Mauna Loa volcano has grown tremendously in the past few decades ( Dietterich and Cashman, 2014 ), and few island residents are prepared for the even larger magnitude explosive eruptions that are documented in the last 500 years ( Swanson et al., 2014 ).

All western states have potentially active volcanoes, from New Mexico, where lava flows have reached within a few kilometers of the Texas and Oklahoma borders ( Fitton et al., 1991 ), to Montana, which borders the Yellowstone caldera ( Christiansen, 1984 ). These volcanoes range from immense calderas that formed from super-eruptions ( Mastin et al., 2014 ) to small-volume basaltic volcanic fields that erupt lava flows and tephra for a few months to a few decades. Some of these eruptions are monogenic (erupt just once) and pose a special challenge for forecasting. Rates of activity in these distributed volcanic fields are low, with many eruptions during the past few thousand years (e.g., Dunbar, 1999 ; Fenton, 2012 ; Laughlin et al., 1994 ), but none during the past hundred years.

1.3 THE STRUCTURE OF A VOLCANO

Volcanoes often form prominent landforms, with imposing peaks that tower above the surrounding landscape, large depressions (calderas), or volcanic fields with numerous dispersed cinder cones, shield volcanoes, domes, and lava flows. These various landforms reflect the plate tectonic setting, the ways in which those volcanoes erupt, and the number of eruptions. Volcanic landforms change continuously through the interplay between constructive processes such as eruption and intrusion, and modification by tectonics, climate, and erosion. The stratigraphic and structural architecture of volcanoes yields critical information on eruption history and processes that operate within the volcano.

Beneath the volcano lies a magmatic system that in most cases extends through the crust, except during eruption. Depending on the setting, magmas may rise

___________________

1 Personal communication from Charles Mandeville, Program Coordinator, Volcano Hazards Program, U.S. Geological Survey, on November 26, 2016.

directly from the mantle or be staged in one or more storage regions within the crust before erupting. The uppermost part (within 2–3 km of Earth’s surface) often hosts an active hydrothermal system where meteoric groundwater mingles with magmatic volatiles and is heated by deeper magma. Identifying the extent and vigor of hydrothermal activity is important for three reasons: (1) much of the unrest at volcanoes occurs in hydrothermal systems, and understanding the interaction of hydrothermal and magmatic systems is important for forecasting; (2) pressure buildup can cause sudden and potentially deadly phreatic explosions from the hydrothermal system itself (such as on Ontake, Japan, in 2014), which, in turn, can influence the deeper magmatic system; and (3) hydrothermal systems are energy resources and create ore deposits.

Below the hydrothermal system lies a magma reservoir where magma accumulates and evolves prior to eruption. Although traditionally modeled as a fluid-filled cavity, there is growing evidence that magma reservoirs may comprise an interconnected complex of vertical and/or horizontal magma-filled cracks, or a partially molten mush zone, or interleaved lenses of magma and solid material ( Cashman and Giordano, 2014 ). In arc volcanoes, magma chambers are typically located 3–6 km below the surface. The magma chamber is usually connected to the surface via a fluid-filled conduit only during eruptions. In some settings, magma may ascend directly from the mantle without being stored in the crust.

In the broadest sense, long-lived magma reservoirs comprise both eruptible magma (often assumed to contain less than about 50 percent crystals) and an accumulation of crystals that grow along the margins or settle to the bottom of the magma chamber. Physical segregation of dense crystals and metals can cause the floor of the magma chamber to sag, a process balanced by upward migration of more buoyant melt. A long-lived magma chamber can thus become increasingly stratified in composition and density.

The deepest structure beneath volcanoes is less well constrained. Swarms of low-frequency earthquakes at mid- to lower-crustal depths (10–40 km) beneath volcanoes suggest that fluid is periodically transferred into the base of the crust ( Power et al., 2004 ). Tomographic studies reveal that active volcanic systems have deep crustal roots that contain, on average, a small fraction of melt, typically less than 10 percent. The spatial distribution of that melt fraction, particularly how much is concentrated in lenses or in larger magma bodies, is unknown. Erupted samples preserve petrologic and geochemical evidence of deep crystallization, which requires some degree of melt accumulation. Seismic imaging and sparse outcrops suggest that the proportion of unerupted solidified magma relative to the surrounding country rock increases with depth and that the deep roots of volcanoes are much more extensive than their surface expression.

1.4 MONITORING VOLCANOES

Volcano monitoring is critical for hazard forecasts, eruption forecasts, and risk mitigation. However, many volcanoes are not monitored at all, and others are monitored using only a few types of instruments. Some parameters, such as the mass, extent, and trajectory of a volcanic ash cloud, are more effectively measured by satellites. Other parameters, notably low-magnitude earthquakes and volcanic gas emissions that may signal an impending eruption, require ground-based monitoring on or close to the volcanic edifice. This section summarizes existing and emerging technologies for monitoring volcanoes from the ground and from space.

Monitoring Volcanoes on or Near the Ground

Ground-based monitoring provides data on the location and movement of magma. To adequately capture what is happening inside a volcano, it is necessary to obtain a long-term and continuous record, with periods spanning both volcanic quiescence and periods of unrest. High-frequency data sampling and efficient near-real-time relay of information are important, especially when processes within the volcano–magmatic–hydrothermal system are changing rapidly. Many ground-based field campaigns are time intensive and can be hazardous when volcanoes are active. In these situations, telemetry systems permit the safe and continuous collection of data, although the conditions can be harsh and the lifetime of instruments can be limited in these conditions.

Ground-based volcano monitoring falls into four broad categories: seismic, deformation, gas, and thermal monitoring ( Table 1.1 ). Seismic monitoring tools,

TABLE 1.1 Ground-Based Instrumentation for Monitoring Volcanoes

including seismometers and infrasound sensors, are used to detect vibrations caused by breakage of rock and movement of fluids and to assess the evolution of eruptive activity. Ambient seismic noise monitoring can image subsurface reservoirs and document changes in wave speed that may reflect stress. changes. Deformation monitoring tools, including tiltmeters, borehole strainmeters, the Global Navigation Satellite System (GNSS, which includes the Global Positioning System [GPS]), lidar, radar, and gravimeters, are used to detect the motion of magma and other fluids in the subsurface. Some of these tools, such as GNSS and lidar, are also used to detect erupted products, including ash clouds, pyroclastic density currents, and volcanic bombs. Gas monitoring tools, including a range of sensors ( Table 1.1 ), and direct sampling of gases and fluids are used to detect magma intrusions and changes in magma–hydrothermal interactions. Thermal monitoring tools, such as infrared cameras, are used to detect dome growth and lava breakouts. Continuous video or photographic observations are also commonly used and, despite their simplicity, most directly document volcanic activity. Less commonly used monitoring technologies, such as self-potential, electromagnetic techniques, and lightning detection are used to constrain fluid movement and to detect

ash clouds. In addition, unmanned aerial vehicles (e.g., aircraft and drones) are increasingly being used to collect data. Rapid sample collection and analysis is also becoming more common as a monitoring tool at volcano observatories. A schematic of ground-based monitoring techniques is shown in Figure 1.6 .

Monitoring Volcanoes from Space

Satellite-borne sensors and instruments provide synoptic observations during volcanic eruptions when collecting data from the ground is too hazardous or where volcanoes are too remote for regular observation. Repeat-pass data collected over years or decades provide a powerful means for detecting surface changes on active volcanoes. Improvements in instrument sensitivity, data availability, and the computational capacity required to process large volumes of data have led to a dramatic increase in “satellite volcano science.”

Although no satellite-borne sensor currently in orbit has been specifically designed for volcano monitoring, a number of sensors measure volcano-relevant

TABLE 1.2 Satellite-Borne Sensor Suite for Volcano Monitoring

NOTE: AIRS, Atmospheric Infrared Sounder; ALOS, Advanced Land Observing Satellite; ASTER, Advanced Spaceborne Thermal Emission and Reflection Radiometer; AVHRR, Advanced Very High Resolution Radiometer; CALIPSO, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation; COSMO-SkyMed, Constellation of Small Satellites for Mediterranean Basin Observation; GOES, Geostationary Operational Environmental Satellite; IASI, Infrared Atmospheric Sounding Interferometer; MISR, Multi-angle Imaging SpectroRadiometer; MLS, Microwave Limb Sounder; MODIS, Moderate Resolution Imaging Spectroradiometer; OMI, Ozone Monitoring Instrument; OMPS, Ozone Mapping and Profiler Suite; SAGE, Stratospheric Aerosol and Gas Experiment.

parameters, including heat flux, gas and ash emissions, and deformation ( Table 1.2 ). Thermal infrared data are used to detect eruption onset and cessation, calculate lava effusion rates, map lava flows, and estimate ash column heights during explosive eruptions. In some cases, satellites may capture thermal precursors to eruptions, although low-temperature phenomena are challenging to detect. Both high-temporal/low-spatial-resolution (geostationary orbit) and high-spatial/low-temporal-resolution (polar orbit) thermal infrared observations are needed for global volcano monitoring.

Satellite-borne sensors are particularly effective for observing the emission and dispersion of volcanic gas and ash plumes in the atmosphere. Although several volcanic gas species can be detected from space (including SO 2 , BrO, OClO, H 2 S, HCl, and CO; Carn et al., 2016 ), SO 2 is the most readily measured, and it is also responsible for much of the impact of eruptions on climate. Satellite measurements of SO 2 are valuable for detecting eruptions, estimating global volcanic fluxes and recycling of other volatile species, and tracking volcanic clouds that may be hazardous to aviation in near real time. Volcanic ash cloud altitude is most accurately determined by spaceborne lidar, although spatial coverage is limited. Techniques for measuring volcanic CO 2 from space are under development and could lead to earlier detection of preeruptive volcanic degassing.

Interferometric synthetic aperture radar (InSAR) enables global-scale background monitoring of volcano deformation ( Figure 1.7 ). InSAR provides much higher spatial resolution than GPS, but lower accuracy and temporal resolution. However, orbit repeat times will diminish as more InSAR missions are launched, such as the European Space Agency’s recently deployed Sentinel-1 satellite and the NASA–Indian Space Research Organisation synthetic aperture radar mission planned for launch in 2020.

1.5 ERUPTION BEHAVIOR

Eruptions range from violently explosive to gently effusive, from short lived (hours to days) to persistent over decades or centuries, from sustained to intermittent, and from steady to unsteady ( Siebert et al., 2015 ). Eruptions may initiate from processes within the magmatic system ( Section 1.3 ) or be triggered by processes and properties external to the volcano, such as precipitation, landslides, and earthquakes. The eruption behavior of a volcano may change over time. No classification scheme captures this full diversity of behaviors (see Bonadonna et al., 2016 ), but some common schemes to describe the style, magnitude, and intensity of eruptions are summarized below.

Eruption Magnitude and Intensity

The size of eruptions is usually described in terms of total erupted mass (or volume), often referred to as magnitude, and mass eruption rate, often referred to as intensity. Pyle (2015) quantified magnitude and eruption intensity as follows:

magnitude = log 10 (mass, in kg) – 7, and

intensity = log 10 (mass eruption rate, in kg/s) + 3.

The Volcano Explosivity Index (VEI) introduced by Newhall and Self (1982) assigns eruptions to a VEI class based primarily on measures of either magnitude (erupted mass or volume) or intensity (mass eruption rate and/or eruption plume height), with more weight given to magnitude. The VEI classes are summarized in Figure 1.8 . The VEI classification is still in use, despite its many limitations, such as its reliance on only a few types of measurements and its poor fit for small to moderate eruptions (see Bonadonna et al., 2016 ).

Smaller VEI events are relatively common, whereas larger VEI events are exponentially less frequent ( Siebert et al., 2015 ). For example, on average about three VEI 3 eruptions occur each year, whereas there is a 5 percent chance of a VEI 5 eruption and a 0.2 percent chance of a VEI 7 (e.g., Crater Lake, Oregon) event in any year.

Eruption Style

The style of an eruption encompasses factors such as eruption duration and steadiness, magnitude, gas flux, fountain or column height, and involvement of magma and/or external source of water (phreatic and phreatomagmatic eruptions). Eruptions are first divided into effusive (lava producing) and explosive (pyroclast producing) styles, although individual eruptions can be simultaneously effusive and weakly explosive, and can pass rapidly and repeatedly between eruption styles. Explosive eruptions are further subdivided into styles that are sustained on time scales of hours to days and styles that are short lived ( Table 1.3 ).

Classification of eruption style is often qualitative and based on historical accounts of characteristic eruptions from type-volcanoes. However, many type-volcanoes exhibit a range of eruption styles over time (e.g., progressing between Strombolian, Vulcanian, and Plinian behavior; see Fee et al., 2010 ), which has given rise to terms such as subplinian or violent Strombolian.

1.6 ERUPTION HAZARDS

Eruption hazards are diverse ( Figure 1.9 ) and may extend more than thousands of kilometers from an active volcano. From the perspective of risk and impact, it is useful to distinguish between near-source and distal hazards. Near-source hazards are far more unpredictable than distal hazards.

Near-source hazards include those that are airborne, such as tephra fallout, volcanic gases, and volcanic projectiles, and those that are transported laterally on or near the ground surface, such as pyroclastic density currents, lava flows, and lahars. Pyroclastic density currents are hot volcanic flows containing mixtures of gas and micron- to meter-sized volcanic particles. They can travel at velocities exceeding 100 km per hour. The heat combined with the high density of material within these flows obliterates objects in their path, making them the most destructive of volcanic hazards. Lava flows also destroy everything in their path, but usually move slowly enough to allow people to get out of the way. Lahars are mixtures of volcanic debris, sediment, and water that can travel many tens of kilometers along valleys and river channels. They may be triggered during an eruption by interaction between volcanic prod-

TABLE 1.3 Characteristics of Different Eruption Styles

ucts and snow, ice, rain, or groundwater. Lahars can be more devastating than the eruption itself. Ballistic blocks are large projectiles that typically fall within 1–5 km from vents.

The largest eruptions create distal hazards. Explosive eruptions produce plumes that are capable of dispersing ash hundreds to thousands of kilometers from the volcano. The thickness of ash deposited depends on the intensity and duration of the eruption and the wind direction. Airborne ash and ash fall are the most severe distal hazards and are likely to affect many more people than near-source hazards. They cause respiratory problems and roof collapse, and also affect transport networks and infrastructure needed to support emergency response. Volcanic ash is a serious risk to air traffic. Several jets fully loaded with passengers have temporarily lost power on all engines after encountering dilute ash clouds (e.g., Guffanti et al., 2010 ). Large lava flows, such as the 1783 Laki eruption in Iceland, emit volcanic gases that create respiratory problems and acidic rain more than 1,000 km from the eruption. Observed impacts of basaltic eruptions in Hawaii and Iceland include regional volcanic haze (“vog”) and acid rain that affect both agriculture and human health (e.g., Thordarson and Self, 2003 ) and fluorine can contaminate grazing land and water supplies (e.g., Cronin et al., 2003 ). Diffuse degassing of CO 2 can lead to deadly concentrations with fatal consequences such as occurred at Mammoth Lakes, California, or cause lakes to erupt, leading to massive CO 2 releases that suffocate people (e.g., Lake Nyos, Cameroon).

Secondary hazards can be more devastating than the initial eruption. Examples include lahars initiated by storms, earthquakes, landslides, and tsunamis from eruptions or flank collapse; volcanic ash remobilized by wind to affect human health and aviation for extended periods of time; and flooding because rain can no longer infiltrate the ground.

1.7 MODELING VOLCANIC ERUPTIONS

Volcanic processes are governed by the laws of mass, momentum, and energy conservation. It is possible to develop models for magmatic and volcanic phenomena based on these laws, given sufficient information on mechanical and thermodynamic properties of the different components and how they interact with each other. Models are being developed for all processes in volcanic systems, including melt transport in the mantle, the evolution of magma bodies within the crust, the ascent of magmas to the surface, and the fate of magma that erupts effusively or explosively.

A central challenge for developing models is that volcanic eruptions are complex multiphase and multicomponent systems that involve interacting processes over a wide range of length and time scales. For example, during storage and ascent, the composition, temperature, and physical properties of magma and host rocks evolve. Bubbles and crystals nucleate and grow in this magma and, in turn, greatly influence the properties of the magmas and lavas. In explosive eruptions, magma fragmentation creates a hot mixture of gas and particles with a wide range of sizes and densities. Magma also interacts with its surroundings: the deformable rocks that surround the magma chamber and conduit, the potentially volatile groundwater and surface water, a changing landscape over which pyroclastic density currents and lava flows travel, and the atmosphere through which eruption columns rise.

Models for volcanic phenomena that involve a small number of processes and that are relatively amenable to direct observation, such as volcanic plumes, are relatively straightforward to develop and test. In contrast, phenomena that occur underground are more difficult to model because there are more interacting processes. In those cases, direct validation is much more challenging and in many cases impossible. Forecasting ash dispersal using plume models is more straightforward and testable than forecasting the onset, duration, and style of eruption using models that seek to explain geophysical and geochemical precursors. In all cases, however, the use of even imperfect models helps improve the understanding of volcanic systems.

Modeling approaches can be divided into three categories:

• Reduced models make simplifying assumptions about dynamics, heat transfer, and geometry to develop first-order explanations for key properties and processes, such as the velocity of lava flows and pyroclastic density currents, the height of eruption columns, the magma chamber size and depth, the dispersal of tephra, and the ascent of magma in conduits. Well-calibrated or tested reduced models offer a straightforward ap-

proach for combining observations and models in real time in an operational setting (e.g., ash dispersal forecasting for aviation safety). Models may not need to be complex if they capture the most important processes, although simplifications require testing against more comprehensive models and observations.

• Multiphase and multiphysics models improve scientific understanding of complex processes by invoking fewer assumptions and idealizations than reduced models ( Figure 1.10 ), but at the expense of increased complexity and computational demands. They also require additional components, such as a model for how magma in magma chambers and conduits deforms when stressed; a model for turbulence in pyroclastic density currents and plumes; terms that describe the thermal and mechanical exchange among gases, crystals, and particles; and a description of ash aggregation in eruption columns. A central challenge for multiphysics models is integrating small-scale processes with large-scale dynamics. Many of the models used in volcano science build on understanding developed in other science and engineering fields and for other ap-

plications. Multiphysics and multiscale models benefit from rapidly expanding computational capabilities.

• Laboratory experiments simulate processes for which the geometry and physical and thermal processes and properties can be scaled ( Mader et al., 2004 ). Such experiments provide insights on fundamental processes, such as crystal dynamics in flowing magmas, entrainment in eruption columns, propagation of dikes, and sedimentation from pyroclastic density currents ( Figure 1.11 ). Experiments have also been used successfully to develop the subsystem models used in numerical simulations, and to validate computer simulations for known inputs and properties.

The great diversity of existing models reflects to a large extent the many interacting processes that operate in volcanic eruptions and the corresponding simplifying assumptions currently required to construct such models. The challenge in developing models is often highlighted in discrepancies between models and observations of natural systems. Nevertheless, eruption models reveal essential processes governing volcanic eruptions, and they provide a basis for interpreting measurements from prehistoric and active eruptions and for closing observational gaps. Mathematical models offer a guide for what observations will be most useful. They may also be used to make quantitative and testable predictions, supporting forecasting and hazard assessment.

Volcanic eruptions are common, with more than 50 volcanic eruptions in the United States alone in the past 31 years. These eruptions can have devastating economic and social consequences, even at great distances from the volcano. Fortunately many eruptions are preceded by unrest that can be detected using ground, airborne, and spaceborne instruments. Data from these instruments, combined with basic understanding of how volcanoes work, form the basis for forecasting eruptions—where, when, how big, how long, and the consequences.

Accurate forecasts of the likelihood and magnitude of an eruption in a specified timeframe are rooted in a scientific understanding of the processes that govern the storage, ascent, and eruption of magma. Yet our understanding of volcanic systems is incomplete and biased by the limited number of volcanoes and eruption styles observed with advanced instrumentation. Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing identifies key science questions, research and observation priorities, and approaches for building a volcano science community capable of tackling them. This report presents goals for making major advances in volcano science.

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ENCYCLOPEDIC ENTRY

A volcano is an opening in a planet or moon’s crust through which molten rock and gases trapped under the surface erupt, often forming a hill or mountain.

Volcanic eruption

Volcanic eruptions can create colorful and dramatic displays, such as this eruption of this volcano in the Virunga Moutains of the Democratic Republic of the Congo.

Photograph by Chris Johns

A volcano is an opening in a planet or moon’s crust through which molten rock, hot gases, and other materials erupt . Volcanoes often form a hill or mountain as layers of rock and ash build up from repeated eruptions .

Volcanoes are classified as active, dormant, or extinct. Active volcanoes have a recent history of eruptions ; they are likely to erupt again. Dormant volcanoes have not erupted for a very long time but may erupt at a future time. Extinct volcanoes are not expected to erupt in the future.

Inside an active volcano is a chamber in which molten rock, called magma , collects. Pressure builds up inside the magma chamber, causing the magma to move through channels in the rock and escape onto the planet’s surface. Once it flows onto the surface the magma is known as lava .

Some volcanic eruptions are explosive, while others occur as a slow lava flow. Eruptions can occur through a main opening at the top of the volcano or through vents that form on the sides. The rate and intensity of eruptions, as well as the composition of the magma, determine the shape of the volcano.

Volcanoes are found on both land and the ocean floor. When volcanoes erupt on the ocean floor, they often create underwater mountains and mountain ranges as the released lava cools and hardens. Volcanoes on the ocean floor become islands when the mountains become so large they rise above the surface of the ocean.

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Related Resources

Volcanoes, explained

These fiery peaks have belched up molten rock, hot ash, and gas since Earth formed billions of years ago.

Volcanoes are Earth's geologic architects. They've created more than 80 percent of our planet's surface, laying the foundation that has allowed life to thrive. Their explosive force crafts mountains as well as craters. Lava rivers spread into bleak landscapes. But as time ticks by, the elements break down these volcanic rocks, liberating nutrients from their stony prisons and creating remarkably fertile soils that have allowed civilizations to flourish.

There are volcanoes on every continent, even Antarctica. Some 1,500 volcanoes are still considered potentially active around the world today; 161 of those—over 10 percent—sit within the boundaries of the United States .

But each volcano is different. Some burst to life in explosive eruptions, like the 1991 eruption of Mount Pinatubo , and others burp rivers of lava in what's known as an effusive eruption, like the 2018 activity of Hawaii's Kilauea volcano. These differences are all thanks to the chemistry driving the molten activity. Effusive eruptions are more common when the magma is less viscous, or runny, which allows gas to escape and the magma to flow down the volcano's slopes. Explosive eruptions, however, happen when viscous molten rock traps the gasses, building pressure until it violently breaks free.

How do volcanoes form?

The majority of volcanoes in the world form along the boundaries of Earth's tectonic plates—massive expanses of our planet's lithosphere that continually shift, bumping into one another. When tectonic plates collide, one often plunges deep below the other in what's known as a subduction zone .

As the descending landmass sinks deep into the Earth, temperatures and pressures climb, releasing water from the rocks. The water slightly reduces the melting point of the overlying rock, forming magma that can work its way to the surface—the spark of life to reawaken a slumbering volcano.

Not all volcanoes are related to subduction, however. Another way volcanoes can form is what's known as hotspot volcanism. In this situation, a zone of magmatic activity —or a hotspot—in the middle of a tectonic plate can push up through the crust to form a volcano. Although the hotspot itself is thought to be largely stationary, the tectonic plates continue their slow march, building a line of volcanoes or islands on the surface. This mechanism is thought to be behind the Hawaii volcanic chain .

Where are all these volcanoes?

Some 75 percent of the world's active volcanoes are positioned around the ring of fire , a 25,000-mile long, horseshoe-shaped zone that stretches from the southern tip of South America across the West Coast of North America, through the Bering Sea to Japan, and on to New Zealand.

This region is where the edges of the Pacific and Nazca plates butt up against an array of other tectonic plates. Importantly, however, the volcanoes of the ring aren't geologically connected . In other words, a volcanic eruption in Indonesia is not related to one in Alaska, and it could not stir the infamous Yellowstone supervolcano .

What are some of the dangers from a volcano?

Volcanic eruptions pose many dangers aside from lava flows. It's important to heed local authorities' advice during active eruptions and evacuate regions when necessary.

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One particular danger is pyroclastic flows, avalanches of hot rocks, ash, and toxic gas that race down slopes at speeds as high as 450 miles an hour . Such an event was responsible for wiping out the people of Pompeii and Herculaneum after Mount Vesuvius erupted in A.D. 79 .

Similarly, volcanic mudflows called lahars can be very destructive. These fast-flowing waves of mud and debris can race down a volcano's flanks, burying entire towns.

Ash is another volcanic danger. Unlike the soft, fluffy bits of charred wood left after a campfire, volcanic ash is made of sharp fragments of rocks and volcanic glass each less than two millimeters across. The ash forms as the gasses within rising magma expand, shattering the cooling rocks as they burst from the volcano's mouth. It's not only dangerous to inhale , it's heavy and builds up quickly. Volcanic ash can collapse weak structures, cause power outages, and is a challenge to shovel away post-eruption.

Can we predict volcanic eruptions?

Volcanoes give some warning of pending eruption, making it vital for scientists to closely monitor any volcanoes near large population centers. Warning signs include small earthquakes, swelling or bulging of the volcano's sides, and increased emission of gasses from its vents. None of those signs necessarily mean an eruption is imminent, but they can help scientists evaluate the state of the volcano when magma is building.

However, it's impossible to say exactly when, or even if, any given volcano will erupt. Volcanoes don't run on a timetable like a train. This means it's impossible for one to be “overdue” for eruption —no matter what news headlines say.

What is the largest eruption in history?

The deadliest eruption in recorded history was the 1815 explosion of Mount Tabora in Indonesia. The blast was one of the most powerful ever documented and created a caldera —essentially a crater—4 miles across and more than 3,600 feet deep. A superheated plume of hot ash and gas shot 28 miles into the sky, producing numerous pyroclastic flows when it collapsed.

The eruption and its immediate dangers killed around 10,000 people. But that wasn't its only impact. The volcanic ash and gas injected into the atmosphere obscured the sun and increased the reflectivity of Earth, cooling its surface and causing what's known as the year without a summer. Starvation and disease during this time killed some 82,000 more people, and the gloomy conditions are often credited as the inspiration for gothic horror tales, such as Mary Shelley's Frankenstein .

Although there have been several big eruptions in recorded history, volcanic eruptions today are no more frequent than there were a decade or even a century ago. At least a dozen volcanoes erupt on any given day. As monitoring capacity for—and interest in—volcanic eruptions increases, coverage of the activity more frequently appears in the news and on social media. As Erik Klemetti, associate professor of geosciences at Denison University, writes in The Washington Post : “The world is not more volcanically active, we’re just more volcanically aware.”

Related Topics

• VOLCANIC ERUPTIONS

Volcanoes don’t just erupt on schedule—but they have been in Iceland

Why Iceland's latest eruption may be the most dangerous in recent history

Startling volcanic activity has town in Iceland bracing for crisis

A huge volcano near Naples has been convulsing. What does it mean?

Mysteries lurk below Iceland's restless volcanoes

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• 22 April 2024

How volcanoes shaped our planet — and why we need to be ready for the next big eruption

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Heather Handley is an associate professor of volcanic hazards and geoscience communication in the Department of Applied Earth Sciences at the University of Twente in Enschede, the Netherlands.

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Lava erupts from a volcano in Iceland, part of a series of eruptions that began last year. Credit: Anton Brink/Anadolu via Getty

Adventures in Volcanoland: What Volcanoes Tell Us About the World and Ourselves Tamsin Mather Abacus (2024)

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Your burning questions about volcanoes, answered

Asu experts explain these molten mysteries.

Volcano! That little word brings so much to our minds — streams of lava and clouds of ash, rumbling mountains, the might of a planet’s fiery underbelly, and our own nervous anticipation, curiosity and fear.

In fact, if it seems like more and more people have volcanoes on the brain, there’s a good reason.

It’s not necessarily that the number of volcanic eruptions is increasing, though media coverage of dangerous eruptions, such as the one in Indonesia on Aug. 10 or other recent ones in New Zealand and the Philippines, may make it appear that way. Scientists can’t say without more data from Earth’s history.

What is certain is that humans (and our stuff) take up more space on the planet than ever before, putting more people in the paths of volcanoes.

“The impact of volcanic eruptions is increasing,” volcanologist Amanda Clarke said. “As the global population grows, more people are being affected by eruptions, so we care about them more.”

Despite their growing effect on our lives, volcanoes seem to retain their air of mystery, leaving many of us with questions. Where do they come from? What causes eruptions? How do scientists predict them?

Clarke and fellow volcanologist Christy Till — both faculty in the Arizona State University  School of Earth and Space Exploration  — answer these questions and more to help us understand how to safely live in the shadows of these mighty forces of nature.

Click to view larger image. Illustration by Shireen Dooling

How does a volcano form?

There are two sides to the making of a volcano: what happens below ground and what happens above.

Events below ground have to do with plate tectonics. This is the theory that the Earth’s crust — the outer shell on which we live — is broken up into plates that move around on top of Earth’s mantle like ice cubes in a glass of water. Scientists see it as the force behind earthquakes, mountains, continent migration and volcano formation.

“Scientists for a long time have scratched their heads trying to figure out why these volcanoes occur where they do.”  — Christy Till

There are three basic types of tectonic environments where volcanoes grow.

The first is a convergent plate boundary, where two plates crash and an oceanic plate slips underneath another plate, bringing water and carbon dioxide into the mantle. This triggers a magma-melting process and creates more explosive volcanoes. This process created the Ring of Fire, an arch of volcanoes that wraps around the Pacific Ocean.

The second, a divergent plate boundary, occurs when a gap opens up between two plates. The gap is filled in by the mantle underneath, causing magma to melt. These volcanoes are common on the ocean floor and erupt continuously as the plates keep going their separate ways.

Volcanoes that form in the middle of a plate are called hot spot volcanoes.

“Scientists for a long time have scratched their heads trying to figure out why these volcanoes occur where they do,” Till said. “Our best guess is that there’s magma or mantle rising up underneath, and for some reason, it’s just hotter than in other places, so we get a volcano.”

Above ground, the part of the volcano we can see is formed by eruptions.

For example, Mount St. Helens, a composite volcano in Washington, grew over time as layers of debris from a mix of effusive eruptions (think gooey lava) and explosive eruptions (think pumice stone and ash) built on top of each other.

Sunset Crater, a cinder cone volcano in Arizona, ejected glowing fountains of lava and ash when it erupted, which then fell around the crater to create its steep slopes.

And Kilauea, a shield volcano in Hawaii, formed its wide but shallow slopes as its lava spread out in all directions and built up in layers over time.

However, the type of eruption, and therefore volcano, circles back to another underground element.

“The composition of the magma, and the process deep in the earth that forms it, controls the eruption style to a large extent,” Till said.

What is magma?

Magma is the molten material that sits under or inside the Earth’s crust. (Lava is magma that has reached the surface through a volcano.) Till’s lab, the  Experimental Petrology and Igneous processes Center , looks at how magma forms on Earth and on other planets, as well as the underground processes that lead up to an eruption.

One of the surprises that researchers have learned in the last 10 years, she says, is that the magma below a volcano is not the cauldron of bubbling, liquid goo we might imagine.

“In fact, what’s below a volcano is more like a slushie. In a slushie, you have mostly ice crystals and some liquid, and at first, it’s hard to suck it through a straw because it’s mostly ice. You have to wait until it melts a little to get it through a straw.”

Magma, too, is composed of crystals (the geological kind) with just a little bit of liquid. Something must happen to the magma underground to warm it up, making it liquid enough to erupt. To study those processes, Till gathers samples of those crystals, which she likens to “little black boxes,” from volcanic deposits on the surface and examines them with microscopes.

“These crystals have little zones in them, much like tree rings. They can tell us about the temperature, pressure and composition of the magma chamber, and also how long before an eruption these specific events happened,” she said.

Video by ASU Research

What happens during a volcanic eruption?

First, a fresher, hotter, more liquid magma rises from deeper in the Earth’s mantle and warms the slushie magma in the volcano’s chamber. One way for it to arrive there is via an earthquake, which might push up fresh magma or open new pathways for it to travel upward. However, not every earthquake can warm a magma chamber and cause an eruption, Till notes.

“There’s also a possibility that the seismic waves passing through the crust can kind of jiggle a magma body and cause it to fizz. Just like with a soda, those bubbles can generate overpressure and buoyancy, driving an eruption,” Clarke said.

As the new and old magmas mix, the crystal mush heats up and comes to the surface. It could be an effusive eruption of syrupy, flowing lava, or it could be an explosive eruption of ash, cinders and hunks of molten rock known as lava bombs. The amount of gas in the body of magma determines how violent the eruption is.

For those that are more explosive, the volcano could generate an ash cloud that travels great distances, which could have indirect effects like roof damage, bad air quality or crop devastation. It could also unleash the significantly more destructive pyroclastic flow, which is a searing wave of dense ash and gases that rushes along the ground, killing and burning everything in its path.

“The plume is the big footprint, but only indirectly dangerous,” Clarke said. “The pyroclastic flows are the smaller footprint, but much more dangerous.”

If the volcano is near a body of water, there is another opportunity for additional destruction — pyroclastic flows entering the sea can cause tsunamis.

How do scientists predict eruptions?

“The bread and butter of prediction is seismic data,” Clarke said. Volcanologists take seismic stations, which measure vibrations in the earth, and distribute them all around a volcano to get the best read on what’s happening underneath.

Another important tool is the tiltmeter, which, as its name suggests, measures any miniscule changes in the level of the earth. Typically, before a volcano erupts, the ground around it inflates slightly, which scientists call deformation.

Observatories typically also monitor gas emissions, such as sulfur dioxide and carbon dioxide, which may indicate changes happening deeper in the volcano.

“If you want to know what a volcano is capable of doing in the future, the first thing you have to do is look at what it did in the past.”  — Amanda Clarke

And finally, cameras — both standard and thermal — help volcanologists keep an eye on activity. Clarke explains that thermal cameras are especially helpful for tall volcanoes whose tops may often be obscured by clouds.

“Using these kinds of data together, you can even predict how much magma there is, and at what depth,” Clarke said.

Having an idea of what a particular volcano can do once it’s ready to erupt is also a critical piece of prediction that allows volcanologists to make safety recommendations.

“If you want to know what a volcano is capable of doing in the future, the first thing you have to do is look at what it did in the past,” Clarke said.

Researchers do this by collecting ash deposits from a wide area and dating them. This gives them an idea of how large a volcano’s eruptions were and how frequently they occurred. However, the method has its limitations. Hardened magma is much harder to date than ash, and supervolcanoes have eruptions so large that the ash travels thousands of miles, making it difficult to determine their true size.

There’s also the trouble of inconsistent eruptions. Volcanoes tend to fluctuate in the size of their eruptions; a big one may be followed by several smaller ones before another large one happens. That’s why it’s crucial, Clarke said, to look over long timespans for an accurate picture of a volcano’s history.

How far in advance scientists can predict an eruption depends on a host of factors, one of which is whether the eruption is large or small. Large eruptions are farther apart, so they might have longer warning times — from weeks away to even decades — while the magma slowly heats up after the last eruption. Small eruptions are closer together, so their warning times are shorter — months to hours. However, an abundance of data means that those predictions are typically more precise than for large eruptions.

How can you stay safe in an area with volcanic activity?

Clarke has seen too many volcanic eruptions to count, but she says that her time on the island of Montserrat while getting her PhD was when she learned how to be safe around them.

“I think some people take a bit of a macho attitude about trying to get close to volcanoes,” she said.

Proper precautions, she argues, help people stay alive.

“The main thing is to understand what the local observatories and scientists are doing. They collect data. They know what’s going on,” she said.

Till has not experienced a volcanic eruption and, despite an academic interest in seeing one, is largely happy to keep it that way.

“I’ve been to volcanoes that could erupt at any time, but I was fortunate enough not to be there when they were erupting,” she said. Like Clarke, by checking in with observatories, she’s managed to keep herself safe in dangerous environments.

In the U.S., you can find the latest reports on activity at the  U.S. Geological Survey website . Abroad, other nations may have an equivalent database online, or you can visit the Smithsonian’s  Global Volcanism Program website , which gathers data from around the world.

These resources can help you find out what the alert level is in the area (and what colored or numbered alert system locals use), and whether there has been any activity recently. Clarke said it’s not a good idea to assume that other groups are communicating with the local observatory and recommends always checking for yourself.

“If you get a permit from the forest service to hike to a crater, that doesn’t mean it’s safe. That doesn’t mean they’ve checked the data.”

What do classifications like active, dormant and extinct mean?

Not much, it turns out.

Clarke explains that people used to classify a volcano as “active” if it had erupted in historic time. The problem with this is that historic time varies from culture to culture, because it refers to the time when written records became available. Volcanoes in Italy have extensive documentation going back thousands of years, but volcanoes in the U.S. don’t have as deep of a written history.

“Having had a historic eruption is a meaningless classification, because there’s no number that goes along with that,” Clarke said.

A dormant volcano is one that is active but not currently erupting, while an extinct volcano has not erupted in historic time and is unlikely to erupt in the future.

A handier — and globally applicable — way to determine if a volcano is active is whether it has erupted during the Holocene, our present epoch which began over 11,000 years ago. However, this marker ultimately has its own flaws. A volcano can have an incredibly long lifespan, sometimes lasting millions of years. Silence in recent millennia doesn’t mean its erupting days are over.

“Whether it erupted in the Holocene is meaningless when it comes to someplace like Yellowstone or the Valles Caldera, whose timescales are way longer than we even have the capacity to document,” Clarke said.

Can a volcanic eruption be stopped?

Ideas for stopping eruptions range from venting gases to relieve volcanic pressure to plugging the top like a cork in a bottle. However, these concepts remain untested, and most volcanologists don’t take such efforts seriously.

What has found some success, though, is using barriers to redirect lava and pyroclastic flows away from towns and important structures. Clarke gives the example of Heimaey, a harbor town in Iceland that experienced a nearby eruption in 1973. The resulting lava flow threatened to close off the bay that was their main economic resource.

“As it started to enter the bay, they got out all the water hoses they had and sprayed it, and it solidified there. They used the lava itself as a barrier,” Clarke said.

Do volcanoes affect the climate?

Volcanic eruptions have both positive and negative effects on the climate. For example, their plumes carry gases like sulfur dioxide, which reach above the clouds into the stratosphere. There, the gas forms into droplets of sulfuric acid.

“The sulfur compounds can be circulated around the globe, and they can filter out the sun’s light and heat to cool global temperatures,” Clarke said.

Researchers speculate that such an event — an 1815 eruption of Mount Tambora in Indonesia — was behind the 1816 “year without a summer” that caused low temperatures and heavy rains in Europe and North America, leading to food shortages.

Whether an eruption can have a worldwide effect may depend on the size and composition of the ash cloud, as well as the volcano’s position on Earth. The cooling effect is always temporary. The longest documented cooling period lasted about three years, though Clarke believes that super eruptions in Earth’s history may have had longer temperature effects.

If you’re thinking that this sounds like a good way to combat today’s warming temperatures, you’re not alone. Some scientists are beginning to research the possibilities of solar engineering — a strategy inspired by volcanoes that would use planes to spray sulfur dioxide into the stratosphere.

Another climate effect of volcanoes is that their ash makes super fertile soil, creating lush environments in the areas surrounding them. The plants and trees that grow in this rich soil capture and store carbon dioxide from the atmosphere.

“What’s in fertilizer? Phosphorus, nitrogen and potassium. Those are abundant in volcanic products,” Clarke said. “Basically, they act as a fertilizer just like you might buy at Agway or ACE Hardware.”

Nutrients from falling ash easily leach into the soil, she adds, making it an excellent delivery system as well.

What are volcanoes like on other planets?

Planets, and moons as well, can have volcanoes very different from those on Earth. Jupiter’s moon Io has more volcanic activity than any other object in our solar system; its lava fountains can be many miles high. And the dwarf planet Ceres has ice volcanoes, or cryovolcanoes. They erupt water instead of magma, which freezes on its surface.

“The compositions of planets are different, so the kinds of magma they have are different, which then gives them unique eruptive behavior,” Till said.

Her lab works to understand the magma of other celestial bodies by creating it in a special device called a piston cylinder, which simulates conditions on the interior of a planet.

“In the same way that you’d mix flour and sugar and eggs to make a cake, we mix silica and magnesium and iron and other elements in the proportion we want to study. Then we put them in our equivalent of an oven to make magma at high pressures and temperatures,” Till said. “When we do this, we can discover how magmas on other planets are different.”

Her team has begun work on a new project that will study the types of magma that may exist on planets outside our solar system, known as exoplanets. Knowing more about their magma will give researchers glimpses into those planets’ volcanic behavior.

“Over 4,000 exoplanets have been confirmed in the last five years or so, and we’re just starting to investigate them,” Till said. “It’s an exciting time.”

Top photo from Shutterstock.

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What Causes a Volcano to Erupt?

Volcanic eruptions are among the most stunning phenomena in the natural world. Volcanoes erupt because of the way  heat  moves beneath  Earth ’s surface. Heat is conveyed from the planet’s interior to its surface largely by  convection —the transfer of heat by movement of a heated fluid. In this case, the fluid is magma —molten or partially molten rock —which is formed by the partial melting of Earth's mantle and crust. The magma rises, and, in the last step in this heat-releasing process, erupts at the surface through volcanoes.

Most volcanoes are associated with  plate tectonic activity. For example, volcanoes of  Japan ,  Iceland ,  Indonesia , and numerous other places occur on the margins of the massive solid rocky plates that make up Earth’s surface. When one plate slides under another, water trapped in the subducted, sinking plate is squeezed out of it by enormous pressure, which produces enough heat to melt nearby rock, forming magma. Since the magma is more buoyant than the surrounding rock, it rises, and it may collect in chambers nearer to the surface. As a chamber fills up, the pressure inside may increase. When the downward pressure produced by the weight of rock above the chamber is less than the upward pressure produced by rock below the chamber, cracks often form above. Eventually the upward pressure may push the magma through the cracks and out of vents at the surface, where it becomes  lava . In fact, strictly speaking, the term  volcano  refers to just such a vent, although it can also refer to the landform created by the accumulation of solidified lava and volcanic debris near the vent.

Far from tectonic plate boundaries, a smaller number of volcanoes occur at hotspots , where rising magma melts through the crust. The volcanoes of  Hawaii  are good examples of hotspot volcanoes.

Geography Notes

Essay on volcanoes: top 7 essays on volcanoes| disasters | geography.

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Here is a compilation of essays on ‘Volcanoes’ for class 7, 8, 9, 10. Find paragraphs, long and short essays on ‘Volcanoes’ especially written for school students.

Essay on Volcanoes

Essay Contents:

• Essay on the World Distribution of Volcanoes

Essay # 1. Concept of Vulcanicity :

The terms volcanoes, mechanism of volcanoes and vulcanicity are more or less synonymous to com­mon man but these have different connotations in geology and geography. ‘A volcano is a vent, or opening, usually circular or nearly circular in form, through which heated materials consisting of gases, water, liquid lava and fragments of rocks are ejected from the highly heated interior to the surface of the earth’.

According to A. Holmes and D.L. Holmes (1978) a volcano is essentially a fissure or vent, communicating with the interior, from which flows of lava, fountains of incandescent spray or explosive bursts of gases and volcanic ashes are erupted at the surface.

On the other hand, ‘the term vulcanicity covers all those processes in which molten rock mate­rial or magma rises into the crust or is poured out on its surface, there to solidify as a crystalline or semicrystaline rock’.

Some scientists have also used the term of vulcanism as synonym to the term of vulcanicity. For example, P.G. Worcester (1948) has maintained that ‘vulcanism includes all phenomena connected with the movement of heated material from the interior to or towards the surface of the earth.’

It is apparent from the above definitions of volcano and vulcanicity (vulcanism) that the later (vulcanicity) is a broader mechanism which is related to both the environments, endogenetic and exogenetic. In other words, vulcanicity includes all those processes and mechanisms which are related to the origin of magmas, gases and vapour, their ascent and appear­ance on the earth’s surface in various forms.

It is evident that the vulcanicity has two components which operate below the crustal surface and above the crust. The endogenetic mechanism of vulcanicity includes the creation of hot and liquid magmas and gases in the mantle and the crust, their expansion and upward ascent, their intrusion, cooling and solidification in various forms below the crustal surface (e.g., batholiths, laccoliths, sills, dykes, lopoliths, phacoliths etc.) while the exogenous mechanism includes the process of appearance of lava, volcanic dusts and ashes, fragmen­tal material, mud smoke etc. in different forms e.g., fissure flow or lava flood (fissure or quiet type of volcanic eruption), violent explosion (central type of volcanic eruption), hot springs, geysers, fumaroles, solfatara, mud volcanoes etc. It may be, thus, con­cluded that the vulcanicity is a broader mechanism which includes several events and processes which work below the crust as well as above the crust whereas volcano is a part of vulcanicity (vulcanism).

Essay # 2. Components of Volcanoes :

Volcanoes of explosive type or central eruption type are associated with the accumulated volcanic materials in the form of cones which are called as volcanic cones or simply volcanic mountains. There is a vent or opening, of circular or nearly circular shape, almost in the centre of the summital part of the cone.

This vent is called as volcanic vent or volcanic mouth which is connected with the interior part of the earth by a narrow pipe, which is called as volcanic pipe. Vol­canic materials of various sorts are ejected through this pipe and the vent situated at the top of the pipe. The enlarged form of the volcanic vent is known as volcanic crater and caldera. Volcanic materials include lavas, volcanic dusts and ashes, fragmental materials etc. (fig. 9.1).

Essay # 3. Types of Volcanoes:

There is a wide range of variations in the mode of volcanic eruptions and their periodicity.

Thus, vocanoes are classified on the basis of:

(i) The mode of eruption, and

(ii) The period of eruption and the nature of their activities.

(i) Classification on the Basis of the Nature of Volcanic Eruptions :

Volcanic eruptions occur mostly in two ways viz.:

(i) Violent and explosive type of eruption of lavas, volcanic dusts, volcanic ashes and fragmental materi­als through a narrow pipe and small opening under the impact of violent gases, and

(ii) Quiet type or fissure eruption along a long fracture or fissure or fault due to weak gases and huge volume of lavas.

Thus, on the basis of the nature and intensity of eruptions volcanoes are divided into two types e.g.:

(1) Central eruption type or explosive eruption type, and

(2) Fissure eruption type or quiet eruption type.

(1) Volcanoes of central eruption type:

Central eruption type or explosive eruption type of volcanoes occurs through a central pipe and small opening by breaking and blowing off crustal surface due to violent and explosive gases accumulated deep within the earth. The eruption is so rapid and violent that huge quantity of volcanic materials consisting of lavas, volcanic dusts and ashes, fragmental materials etc., are ejected upto thousands of metres in the sky.

These materials after falling down accumulate around the volcanic vent and form volcanic cones of various sorts. Such volcanoes are very destructive and are disastrous natural hazards.

Explosive volcances are further divided into 5 sub-types on the basis of difference in the intensity of eruption, variations in the ejected volcanic material and the period of the action of volcanic events as given below:

(i) Hawaiin type of volcanoes:

Such volcanoes erupt quietly due to less viscous lavas and non-violent nature of gases. Rounded blisters of hot and glowing mass/boll of lavas (blebs of molten lava) when caught by a strong wind glide in the air like red and glowing hairs. The Hawaiin people consider these long glassy threads of red molten lava as Pele’s hair (Pele is the Hawaiin goddess of fire).

Such volcanoes have been named as Hawaiin type because of the fact that such eruptions are of very common occurrence on Hawaii island. The eruption of Kilavea volcano of the southern Hawaii island in 1959-60 continued for seven days (from November 14 to 20, 1959) when about 30 mil­lion cubic metres of lavas poured out.

The intermittent eruptions continued upto December 21, 1959, when the volcano became dormant. It again erupted on January 13, 1960 and about 100 million cubic metres of lavas were poured out of one kilometre long fissure.

(ii) Strombolian type of volcanoes:

Such volca-noes, named after Stromboli volcano of Lipari island in the Mediterranean Sea, erupt with moderate inten­sity. Besides lava, other volcanic materials like pum­ice, scoria, bombs etc. are also ejected upto greater height in the sky. These materials again fall down in the volcanic craters. The eruptions are almost rhythemic or nearly continuous in nature but sometimes they are interrupted by long intervals.

(iii) Vulcanian type of volcanoes:

These are named after Vulcano of Lipari island in the Mediterranean Sea. Such volcanoes erupt with great force and inten­sity. The lavas are so viscous and pasty that these are quickly solidified and hardened between two eruptions and thus they crust over (plug) the volcanic vents.

These lava crusts obstruct the escape of violent gases during next eruption. Consequently, the violent gases break and shatter the lava crusts into angular fragments and appear in the sky as ash-laden volcanic clouds of dark and often black colour assuming a convoluted or cauli­flower shape (fig. 9.2c).

(iv) Peleean type of volcanoes:

These are named after the Pelee volcano of Martinique Island in the Caribbean Sea. These are the most violent and most explosive type of volcanoes. The ejected lavas are most viscous and pasty. Obstructive domes of lava are formed above the conduits of the volcanoes. Thus, every successive eruption has to blow off these lava domes. Consequently, each successive eruption oc­curs with greater force and intensity making roaring noise.

The most disastrous volcanic eruption of Mount Pelee on May 8,1902 destroyed the whole of the town of St. Pierre killing all the 28,000 inhabitants leaving behind only two survivors to mourn the sad demise of their brethren. Such type of disastrous violent erup­tions are named as nuee ardente meaning thereby ‘glowing cloud’ of hot gases, lavas etc., coming out of a vocanic eruption.

The nuee ardente spread laterally out of the mountain (Mount Pelee) with great speed which caused disastrous avalanches on the hillslopes which plunged down the slope at a speed of about 100 kilometres per hour. The annihilating explosive erup­tion of Krakatoa volcano in 1883 in Krakatoa Island located in Sunda Strait between Java and Sumatra is another example of violent volcanic eruption of this type.

(v) Visuvious type of volcanoes:

These are more or less similar to Vulcanian and Strombolian type of volcanoes, the difference lies only in the intensity of expulsion of lavas and gases. There is extremely vio­lent expulsion of magma due to enormous volume of explosive gases.

Volcanic materials are thrown up to greater height in the sky. The ejected enormous vol­ume of gases and ashes forms thick clouds of ‘cauli­flower form.’ The most destructive type of eruption is called as Plinian type because of the fact that such type of eruption was first observed by Plini in 79 A.D.

(2) Fissure eruption type of volcanoes:

Such vol­canoes occur along a long fracture, fault and fissure and there is slow upwelling of magma from below and the resultant lavas spread over the ground surface. The speed of lava movement depends on the nature of magma, volume of magma, slope of ground surface and temperature conditions. The Laki fissure eruption of 1783 in Iceland was so quick and enormous that huge volume of lavas measuring about 15 cubic kilometers was poured out from a 28-km long fissure. The lava flow was so enormous that it travelled a distance of 350 kilometres.

(ii) Classification on the Basis of Periodicity of Erup­tions :

Volcanoes are divided into 3 types on the basis of period of eruption and interval period between two eruptions of a volcano e.g.:

(i) Active volcanoes,

(ii) Dormant volcanoes, and

(iii) Extinct volcanoes.

(i) Active Volcanoes:

Active volcanoes are those which constantly eject volcanic lavas, gases, ashes and fragmental ma­terials. It is estimated that there are about more than 500 volcanoes in the world. Etna and Stromboli of the Mediterranean Sea are the most significant examples of this category. Stromboli Volcano is known as Light House of the Mediterranean because of continuous emission of burning and luminous incandescent gases.

Most of the active volcanoes are found along the mid- oceanic ridges representing divergent plate margins (constructive plate margins) and convergent plate margins (destructive plate margins represented by eastern and western margins of the Pacific Ocean). The latest eruption took place from Pinatubo volcano in June 1991 in Philippines. Mayon of Philippines re-erupted in Feb. 2000.

(ii) Dormant Volcanoes:

Dormant volcanoes are those which become quiet after their eruptions for some time and there are no indications for future eruptions but suddenly they erupt very violently and cause enormous damage to human health and wealth.

Visuvious volcano is the best example of dormant volcano which erupted first in 79 A.D., then it kept quiet upto 1631 A.D., when it suddenly exploded with great force. The subsequent eruptions occurred in 1803, 1872, 1906, 1927, 1928, and 1929.

(iii) Extinct volcanoes:

The volcanoes are con­sidered extinct when there are no indications of future eruption. The crater is filled up with water and lakes are formed. It may be pointed out that no volcano can be declared permanently dead as no one knows, what is happening below the ground surface.

Essay # 4. Mechanisms and Causes of Vulcanism:

As stated earlier the volcanic eruptions are asso­ciated with weaker zones of the earth surfaces repre­sented by mountain building at the destructive or convergent plate margins and fracture zones repre­sented by constructive or divergent plate boundaries at the splitting zones of mid-oceanic ridges and the zones of transform faults represented by conservative plate boundaries.

The mechanism of vulcanicity (vulcanism) and volcanic eruptions is closely associated with sev­eral interconnected processes such as:

(i) Gradual in­crease of temperature with increasing depth at the rate of 1°C per 32 m due to heat generated from the disintegration of radioactive elements deep within the earth.

(ii) Origin of magma because of lowering of melting point caused by reduction in the pressure of overlying superincumbent load due to fracture caused by splitting of plates and their movement in opposite direction.

(iii) Origin of gases and vapour due to heat­ing of water which reaches underground through per­colation of rainwater and melt-water (water derived through the melting of ice and snow).

(iv) The ascent of magma forced by enormous volume of gases and vapour, and

(v) Finally the occurrence of volcanic eruptions of either violent explosive central type or quiet fissure type depending upon the intensity of gases and vapour and the nature of crustal surface.

Theory of plate tectonics now very well explains the mechanism of vulcanism and volcanic eruptions. In fact, volcanic eruptions are very closely associated with the plate boundaries. It may be pointed out that the types of plate movements and plate boundaries also determine the nature and intensity of volcanic erup­tion. Most of the active fissure volcanoes are found along the mid-oceanic ridges which represent splitting zones of divergent plate boundaries (fig. 9.5).

Two plates move in opposite directions from the mid-oceanic ridges due to thermal convective currents which are originated in the mantle below the crust (plates). This splitting and lateral spreading of plates creates fractures and faults (transform faults) which cause pressure release and lowering of melting point and thus materials of upper mantle lying below the mid-oceanic ridges are melted and move upward as magmas under the impact of enormous volume of accumulated gases and vapour.

This rise of magmas along the mid-oceanic ridges (constructive or divergent plate bounda­ries) causes fissure eruptions of volcanoes and there is constant upwelling of lavas. These lavas are cooled and solidified and are added to the trailing ends of divergent plate boundaries and thus there is constant creation of new basaltic crust.

The volcanic eruptions of Iceland and the islands located along the mid- Atlantic ridge are caused because of sea-floor spread­ing and divergence of plates. It is obvious that diver­gent or constructive plate boundaries are always asso­ciated with quiet type of fissure flows of lavas because the pressure release of superincumbent load due to divergence of plates and formation of fissures and faults is a slow and gradual process.

It is apparent from the above discussion that the mid-oceanic ridges, representing splitting zones, are associated with active volcanoes wherein the supply of lava comes from the upper mantle just below the ridge because of differential melting of the rocks into tholeiitic basalts.

Since there is constant supply of basaltic lavas from below the mid-oceanic ridges and hence the volcanoes are active near the ridges but the supply of lavas decreases with increasing distance from the mid- oceanic ridges and therefore the volcanoes become inactive, dormant and extinct depending on their dis­tances from the source of lava supply, e.g., mid-oceanic ridges.

This fact has been validated on the basis of the study of the basaltic floor of the Atlantic Ocean and the lavas of several islands. It has been found that the islands nearer to the mid-Atlantic Ridge have younger lavas whereas the islands away from the ridge have older lavas. For example, the lavas of Azores islands Situated on either side of the mid-Atlantic Ridge are 4- million years old whereas the lavas of Cape Verde Island, located far away from the said ridge, are 120- million years old.

Destructive or convergent plate boundaries are associated with explosive type of volcanic eruptions. When two convergent plates collide along Benioff zone (subduction zone), comparatively heavier plate margin (boundary) is subducted beneath comparatively lighter plate boundary. The subducted plate margin, after reaching a depth of 100 km or more in the upper mantle, is melted and thus magma is formed.

This magma is forced to ascend by the enormous volume of accumulated explosive gases and thus magma appears as violent volcanic eruption on the earth’s surface. Such type of volcanic eruption is very common along the destructive or convergent plate boundaries which represent the volcanoes of the Circum-Pacific Belt and the Mid-Continental Belt.

The volcanoes of the island arcs and festoons (off the east coast of Asia) are caused due to subduction of oceanic crust (plate) say Pacific e below the continental plate, say Asiatic plate near Japan Trench.

Essay # 5. Hazardous Effects of Volcanic Eruptions :

Volcanic eruptions cause heavy damage to human lives and property through advancing hot lavas and fallout of volcanic materials; destruction to human structures such as buildings, factories, roads, rails, airports, dams and reservoirs through hot lavas and fires caused by hot lavas; floods in the rivers and climatic changes.

A few of the severe damages wrought by volcanic eruptions may be summarized as given below:

(1) Huge volumes of hot and liquid lavas mov­ing at considerably fast speed (recorded speed is 48 km per hour) bury human structures, kill people and ani­mals, destroy agricultural farms and pastures, plug rivers and lakes, burn and destroy forest etc. The great eruption of Mt. Loa on Hawaii poured out such a huge volume of lavas that these covered a distance of 53 km down the slope.

Enormous Laki Lava flow of 1783 A.D. travelled a distance of 350 km engulfing two churches, 15 agricultural farms and killing 24 per cent of the total population of Iceland. The cases of Mt. Pelee eruption of 1902 in Martinique Island (in Carib­bean Sea) (total death 28,000) and St. Helens eruption of 1980 (Washington, USA) are representative exam­ples of damages done by lava movement. The thick covers of green and dense forests on the flanks of Mt. St. Helens were completely destroyed due to severe forest fires kindled by hot lavas.

(2) Fallout of immense quantity of volcanic materials including fragmental materials (pyroclastic materials), dusts and ashes, smokes etc. covers large ground surface and thus destroys crops, vegetation and buildings, disrupts and diverts natural drainage sys­tems, creates health hazards due to poisonous gases emitted during the eruption, and causes killer acid rains.

(3) All types of volcanic eruptions, if not pre­dicted well in advance, causes tremendous losses to precious human lives. Sudden eruption of violent and explosive type through central pipe does not give any time to human beings to evacuate themselves and thus to save themselves from the clutches of death looming large over them. Sudden eruption of Mt. Pelee on the Island of Martinique, West Indies in the Caribbean Sea, on May 8, 1902 destroyed the whole of St. Pierre town and killed all the 28,000 inhabitants leaving behind only two survivors to mourn the sad demise of their brethren.

The heavy rainfall, associated with volcanic eruptions, mixing with falling volcanic dusts and ashes causes enormous mudflow or ‘lahar’ on the steep slopes of volcanic cones which causes sudden deaths of human beings. For example, great mud flow created on the steep slopes of Kelut volcano in Japan in the year 1919 killed 5,500 people.

(4) Earthquakes caused before and after the volcanic eruptions generate destructive tsunamis seis­mic waves which create most destructive and disas­trous sea waves causing innumerable deaths of human beings in the affected coastal areas. Only the example of Krakatoa in 1883 would be sufficient enough to demonstrate the disastrous impact of tsunamis which generated enormous sea waves of 30 to 40 m height which killed 36,000 people in the coastal areas of Java and Sumatra.

(5) Volcanic eruptions also change the radiation balance of the earth and the atmosphere and thus help in causing climatic changes. Greater concentration of volcanic dusts and ashes in the sky reduces the amount of insolation reaching the earth’s surface as they scat­ter and reflect some amount of incoming shortwave solar radiation. Dust veils, on the other hand, do not hinder in the loss of heat of the earth’s surface through outgoing long-wave terrestrial radiation.

The ejection of nearly 20 cubic kilometres of fragmental materials, dusts and ashes upto the height of 23 km in the sky during the violent eruption of Krakatoa volcano on August 27, 1883 formed a thick dust veil in the strato­sphere which caused a global decrease of solar radia­tion received at the earth’s surface by 10 to 20 per cent.

(6) A group of scientists believes that volcanic eruptions and fallout of dusts and ashes cause mass extinction of a few species of animals. Based on this hypothesis the mass extinction of dinosaurs about 60 million years ago has been related to increased world­wide volcanic activity. Acid rains accompanied by volcanic eruptions cause large-scale destruction of plants and animals.

Essay # 6. Volcanic Materials :

Volcanic materials discharged during eruptions include gases and vapour, lavas, fragmental materials and ashes.

(i) Vapour and Gases:

Steam and vapour consti­tute 60 to 90 per cent of the total gases discharged during a volcanic eruption.

Steam and vapour include:

(i) Phreatic vapour, and

(ii) Magmatic vapour whereas volcanic gases include carbon dioxide, nitrogen ox­ides, sulphur dioxide, hydrogen, carbon monoxide, etc.

Besides, certain compounds are also ejected with the volcanic gases e.g., sulphurated hydrogen, hydrochlo­ric acid, volatile chlorides of iron, potassium and other metallic matter.

(ii) Magma and Lava:

Generally, molten rock materials are called magmas below the earth’s surface while they are called lavas when they come at the earth’s surface.

Lavas and magmas are divided on the basis of silica percentage into two groups e.g.:

(i) Acidic magma (higher percentage of silica, and

(ii) Basic lava (low percentage of silica).

Lavas and magmas are also classified on the basis of light and dark coloured minerals into:

(i) Felsic lava, and

(ii) Mafic lava.

Basaltic or mafic lava is characterized by maxi­mum fluidity. Basaltic lava spreads on the ground surface with maximum flow speed (from a few kilome­tres to 100 kilometres per hour, average How speed being 45 to 65 km per hour) due to high fluidity and low viscosity. Basaltic lava is the hottest lava (1,000° to 1,200 C).

Lava flow is divided into two types on the basis of Hawaiin language e.g.:

(i) Pahoehoe, and

(ii) Aa Aa lava flow or block lava flow.

Pahoehoe lava has high fluidity and spreads like thin sheets. This is also known as ropy lava. On the other hand aa aa lava is more viscous. Pahoehoe lava, when solidified in the form of sacks or pillow, is called pillow lava.

(iii) Fragmental or Pyroclastic Materials:

Fragmental or pyroclastic materials thrown during explosive type of eruption are grouped into three categories:

(i) Essential materials include con­solidated forms of live lavas. These are also known as tephra which means ash. Essential materials are unconsolidated and their size is upto 1 mm.

(ii) Acces­sory materials include dead lavas,

(iii) Accidental materials include fragmental materials of crustal rocks.

On the basis of size pyroclastic materials are grouped into:

(i) Volcanic dust (finest particles),

(ii) Volcanic ash (2 mm in size),

(iii) Lapilli (of the size of peas) and

(iv) Volcanic bombs (6 cm or more in size), which are of different shapes viz. ellipsoidal, discoidal, cuboidal, and irregularly rounded.

The dimension of average volcanic bombs ranges from the size of a base-ball or basket-ball to giant size. Sometimes the volcanic bombs weigh 100 tonnes in weight and are thrown upto a distance of 10 km.

Essay # 7. World Distribution of Volcanoes :

Like earthquakes, the spatial distribution of volcanoes over the globe is well marked and well understood because volcanoes are found in a well-defined belt or zone (fig. 9.3). Thus, the distributional pattern of volcanoes is zonal in character.

If we look at the world distribution of volcanoes it appears that the volcanoes are associated with the weaker zones of the earth’s crust and these are closely associated with seismic events say earthquakes. The weaker zones of the earth are represented by folded mountains (western cordillera of North America, Andes, mountains of East Asia and East Indies) with the exceptions of the Alps and the Himalayas, and fault zones.

Volcanoes are also associated with the meeting zones of the continents and oceans. Occurrences of more volcanic eruptions along coastal margins and during wet season denote the fact that there is close relationship between water and volcanic eruption. Similarly, volcanic eruptions are closely associated with the activities of mountain building and fracturing.

Based on plate tectonics, there is close rela­tionship between plate margins and vulcanicity as most of the world’s active volcanoes are associated with the plate boundaries. About 15 per cent of the worlds’ active volcanoes are found along the construc­tive plate margins or divergent plate margins (along the mid-oceanic ridges where two plates move in opposite directions) whereas 80 per cent volcanoes are associ­ated with the destructive or convergent plate boundaries (where two plates collide). Besides, some volcanoes are also found in intraplate regions e.g., volcanoes of the Hawaii Island, fault zones of East Africa etc.

Like earthquakes, there are also three major belts or zones of volcanoes in the world viz.:

(i) Circum-Pacific belt,

(ii) Mid-continental belt, and

(iii) Mid-oceanic ridge belt (fig. 9.3).

(i) Circum-Pacific belt:

The circum-Pacific belt, also known as the ‘volcanic zones of the convergent oceanic plate margins’, includes the volcanoes of the eastern and western coastal areas of the Pacific Ocean (or the western coastal margins of North and South Americas and the eastern coastal margins of Asia), of island arcs and festoons off the east coast of Asia and of the volcanic islands scattered over the Pacific Ocean.

This volcanic belt is also called as the fire girdle of the Pacific or the fire ring of the Pacific. This belt begins from Erebus Mountain of Antarctica and runs north­ward through Andes and Rockies mountains of South and North Americas to reach Alaska from where this belt turns towards eastern Asiatic coast to include the volcanoes of island arcs and festoons (e.g., Sakhalin, Kamchatka, Japan, Philippines etc.).

The belt ulti­mately merges with the mid-continental belt in the East Indies. Most of high volcanic cones and volcanic mountains are found in this belt. Most of the volcanoes are found in chains e.g., the volcanoes of the Aleutian Island, Hawaii Island, Japan etc.

About 22 volcanic mountains are found in group in Ecuador wherein the height of 15 volcanic mountains is more than 4560 m AMSL. Cotopaxi is the highest volcanic mountain of the world (height being 19,613 feet). The other signifi­cant volcanoes are Fuziyama (Japan), Shasta, Rainier and Hood (western cordillera of North America), a valley of ten thousand smokes (Alaska), Mt St. Helens (Washington, USA), Kilavea (Hawaiiland), Mt. Taal, Pinatubo and Mayon (re-eruption in Feb. 2000) of Philippines etc.

Here volcanic eruptions are primarily caused due to collision of American and Pacific plates and due to subduction of Pacific plate below the Asiatic plate.

(ii) Mid-continental Belt:

Mid-continental belt is also known as ‘the vol­canic zones of convergent continental plate mergins’. This belt includes the volcanoes of Alpine mountain chains and the Mediterranean Sea and the volcanoes of fault zone of eastern Africa. Here, the volcanic erup­tions are caused due to convergence and collision of Eurasian plates and African and Indian plates.

The famous volcanoes of the Mediterranean Sea such as Stromboli, Visuvious, Etna etc. and the volcanoes of Aegean Sea are included in this belt. It may be pointed out that this belt does not have the continuity of volcanic eruptions as several gaps (volcanic-free zones) are found along the Alps and the Himalayas because of Compact and thick crust formed due to intense folding activity. The important volcanoes of the fault zone of eastern Africa are Kilimanjaro, Meru, Elgon, Birunga, Rung we etc.

(iii) Mid-Atlantic Belt:

Mid-Atlantic belt includes the volcanoes mainly along the mid-Atlantic ridge which represents the splitting zone of plates. In other words, two plates diverge in opposite directions from the mid-oceanic ridge. Thus, volcanoes mainly of fissure eruption type occur along the constructive or divergent plate mar­gins (boundaries).

The most active volcanic area is Iceland which is located on the mid-Atlantic ridge. This belt begins from Hekla volcanic mountain of Iceland where several fissure eruption type of volca­noes are found. It may be pointed out that since Iceland is located on the mid-Atlantic ridge representing the splitting zone of American plate moving westward and Eurasian plate moving eastward, and hence here is constant upwelling of magmas along the mid-oceanic ridge and wherever the crust becomes thin and weak, fissure flow of lava occurs because of fracture created due to divergence of plates.

The Laki fissure eruption of 1783 A.D. was so quick and enormous that huge volume of lavas measuring about 15 cubic kilometres was poured out from 28-km long fissure. Recently, Hekla and Helgafell volcanoes erupted in the year 1974 and 1973 respectively. Other more active volcanic areas are Lesser Antilles, Southern Antilles, Azores, St. Helena etc.

The dreadful and disastrous eruption of Mount Pelee occurred on May 8,1902 in the town of St. Pierre on the Martinique Island of West Indies in the Caribbean Sea. All the 28,000 inhabitants, except two persons, were killed by the killer volcanic eruption.

(iv) Intra-Plate Volcanoes:

Besides the aforesaid well defined three zones of volcanoes, scattered volca­noes are also found in the inner parts of the continents. Such distributional patterns of volcanoes are called as intraplate volcanoes, the mechanism of their eruption is not yet precisely known. Fig. 9.4 depicts the location of volcanoes of Pacific plate where one branch of volcanoes runs from Hawaii to Kamchatka.

Vulcanicity also becomes active in the inner parts of continental plates. Massive fissure eruption occurred in the north­western parts of North America during Miocene period when 1,00,000 cubic kilometres of basaltic lavas were spread over an area of 1,30,000 km 2 to form Columbian plateau. Similarly, great fissure flows of lavas covered more than 5,00,000 km 2 areas of Peninsular India. Parana of Barazil and Paraguay were formed due to spread of lavas over an area of 7,50,090 km 2 .

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23 Positive and Negative Effects of Volcanoes

In this article, I shall be writing about the positive and negative effects of volcanoes; every year there are tens of volcanic eruptions around the world and this affects humans, animals, plants, and every other thing in the earth’s ecosystem, therefore the impact of volcanoes can’t be overlooked.

A volcano is a geophysical and geochemical phenomenon that involves a violent rupture in the surface of a planet caused by the movement of tectonic plates within the planet’s crust or along ocean floors, this eruption causes hot lava, volcanic ash, and gases to escape from a magma chamber below the surface of the planet.

The term volcano is derived from the name of an ancient Roman god of fire; who bore the Latin name ‘ Vulcan ‘ and in this article, I shall be writing about the 23 positive and negative effects of volcanoes.

Table of Contents

There are many positive and negative effects of volcanoes on the environment , however, the effects of volcanic eruptions and volcanoes can be classified into two major types, they are:

• Negative effects of volcanoes
• Positive effects of volcanoes

17 Negative Effects of Volcanoes

These are the negative effects of volcanoes/volcanic eruptions on the environment:

Loss of Habitats

This is one of the major effects when there is a volcanic eruption, the heat from the eruption and the hot lava cause the destruction of the natural habitat of the species living around the area as it kills every living thing nearby.

The hot lava that flows out of the volcano flows for a long distance before cooling down to form solid rocks thereby taking over the natural habitat of some species and killing most of them in the process.

Causes Death to Wildlife

Volcanoes cause death to wildlife as floating lava and heat from volcanic eruptions kill many animals and plants whenever a volcanic eruption occurs, the ash that rises from the fire also leads to death for the animals around the area who inhale the poisonous gases it contains.

The biggest mass death of animals caused by a volcano was recorded when the Mount St. Helen volcano erupted in 1980 and killed an estimated total of 24,000 animals; over 45 percent of the animals that were killed were hares and about 25 percent were deers.

Causes Air Pollution

Air pollution is one of the major ways volcanoes and volcanic eruptions affect the environment; whenever there is an eruption, large amounts of carbon dioxide, sulfur dioxide, nitrogen, argon, methane, hydrochloric acid, hydrofluoric acid, carbon monoxide, ash, and aerosols( tiny powder-like particles) are released into the atmosphere.

These substances contaminate the air and make it difficult for animals and humans to breathe as only a small quantity of oxygen will be in the atmosphere and some of the gases released are poisonous; all these factors contribute to the pollution of the air; air pollution is one of the biggest environmental problems in the world now.

Every year an estimated 271 million tons of carbon dioxide are released into the atmosphere, which is over 67.75 trillion moles of carbon dioxide molecules.

When volcanoes erupt, hot lava flows out of them, the fast-flowing lava can kill people especially those on its part. The gases and ash from volcanoes make the air unfit or poisonous to breathe thereby causing humans to choke to death, it can also kill humans through forest fires.

The biggest recorded death toll caused by a single volcano erupting is the volcano that erupted in Tambora, Indonesia, in 1815, killing around 92,000 people.

Sudden Weather Changes

Volcanoes; especially the major ones cause drastic and unexpected changes in the weather, they can cause rain, temporary hotness, thunder, lightning and can also have long-term effects on the climate of the area where they occur.

Can Cause Land Slides

Landslides are one of the major effects of volcanoes on the environment; when intense volcanic eruptions occur, they have the capability of causing landslides to occur in the area especially in areas where the ground has high slopes or many slopes.

There is a special kind of landslides that occur only on the slope of volcanos called Lahars; these landslides are powerful and don’t necessarily need a volcanic eruption to occur but can be set off by rainwater.

Affects Economy

In areas where there are volcanoes, whether active ones or not; most people are afraid to set up businesses in the area, also when a volcanic eruption occurs it destroys business establishments and affects many more others.

Causes Deforestation Through Forest fires

When volcanoes erupt the flowing hot lava sets fire to the forest areas around it, this fire if not controlled especially during the dry season can burn down a large expanse of forest thereby increasing the rate of deforestation.

Causes Food Scarcity

The hot lava that flows from volcanoes destroy farmlands thereby reducing food production which results in food scarcity, also after an eruption occurs, the plains around the volcano become very fertile and this attracts some farmers who come and set up their farms in the area only to get devastated at another occurrence.

Can Cause Extinction of Some Species

This is one of the dangerous effects of volcanoes, some of the species in the world are critically endangered and can be located only in a relatively small expanse of land. When hazards like volcanic eruptions occur in such areas, these species are very likely to go extinct.

Damages Properties

This is one of the biggest effects of volcanoes, the heat from the volcano and the hot lava damages or destroys everything on its part; whenever volcanic eruptions occur they cause damage to both private and public properties.

Causes Scarcity of Natural Resources

The lava from an erupted volcano causes forest fire which burns down the trees from which timber, paper. fruits and many other natural resources are gotten from, it also results in the death of wildlife animals, and this results also to the scarcity of bushmeat which is part of the natural resources on the earth.

Causes Diseases

The gases and ash from volcanoes can cause som many diseases including; lung cancer, different types of long-inflammatory diseases, and different kinds of eye problems among many other diseases which affect humans and animals too, it also causes some minor problems like causing itchy-noses.

Causes Water Pollution

One of the bizarre effects of volcanoes is that the ash and hot lava that emerge after an eruption settles on enter into water bodies like; streams, ponds, lakes, rivers, springs, etc. and pollute them; making them unfit for use by humans and animals alike.

Depletes Ozone Layer

The depletion of the ozone layer is one of the effects of volcanoes although they are responsible for about 2 percent of the ozone layer depletion.

When volcanoes erupt some gases escape into the stratosphere, these gases are not directly responsible for the depletion of the ozone layer but the gases that are made up of chlorine compounds undergo go chain reactions to release radicals of chlorine which then reacts with the ozone and destroys it.

Causes Land Pollution Through Acid Rain

When there is a volcanic eruption, so many gases escape from the volcano including sulphur dioxide which gets washed down by rainwater. When the rain washes down sulphur oxide the rain becomes acidic because sulphur oxide is an acid so this causes acid rain which makes the soil unhealthy for plant growth thereby causing land pollution.

Can Cause Tsunamis

Volcanoes can cause tsunamis, especially underwater volcanoes also known as submarine tsunamis; when underwater volcanoes erupt they displace large volumes of water and this sends wave ripples around the water bodies which may build up to cause tsunamis.

Land volcanoes can also cause tsunamis if they are located near water; when such volcanoes erupt, particles of rocks and large quantities of fast-flowing lava may get into the water bodies, these foreign materials displace the water and in the course of doing so send waves around the water body and this can cause a tsunami.

Can Cause Earthquakes

Some earthquakes occur as a result of the effects of volcanoes, such earthquakes are known as volcano-tectonic earthquakes; they are caused by movements and expansion of magmas beneath the earth’s surface, these movements cause pressure changes as they move about and melt more rocks; at some point, they cause the rocks to move or crash and this is exactly what causes the earthquakes.

6 Positive Effects of Volcanoes

These are the positive effects of volcanoes/volcanic eruptions on the environment:

Reduces Heat

One of the surprising effects of volcanoes is that they reduce heat and cool down the planet; this is because volcanic eruptions shoot up much of their gases and send the heat underground into the stratosphere thereby effectively cooling the biosphere.

The volcano eruption that occurred in Tambora, Indonesia, in 1815 is a good reference, it so much cooled the world to the extent that in some parts of the world, that year is dubbed ‘the year without summer’.

Increases Soil Fertility

This is one of the positive effects of volcanoes, despite the environmental pollution caused by volcanoes the role it plays in increasing soil fertility can’t be overlooked; when there is a volcanic eruption a lot of ashes are pushed into the atmosphere, this ashes when the finally settle down tremendously improve the fertility of the soil around the area.

Creates Safe Habitat for Some Animals

This is one of the good effects of volcanoes when there is a volcanic eruption the flowing lava later cools up to form solid rocks and this creates steep and dangerous slopes; the mount dwelling animals then build their nests and live high up the slopes where they will be out of reach for many predators and dangerous for humans.

Tourist Attraction

Whenever there is a volcanic eruption, so many people would love to go sightseeing in the area, therefore the volcano becomes a source or an object of tourist attraction that is of benefit to the host region or country.

Source of Energy

Volcanoes serve as a source of geothermal energy as electrical energy can be generated from geothermal energy in areas where magma lies close to the surface and such areas can be found around volcanos; this helps in increasing the use of renewable energy.

Increases Infiltration

This is one of the effects of volcanoes on the environment although it is rarely mentioned, when there is a volcanic eruption the vibration from the volcano makes the soil on the grounds in and around the area become looser thus helping increase the infiltration as water can easily penetrate such soil.

This is a comprehensive article about the positive and negative effects of volcanoes on the environment, it is good to note that some of these effects like the tectonic earthquakes do not need a volcanic eruption to occur but a volcano.

There are only 23 major positive and negative effects of volcanoes and volcanic eruptions; as regards the way it affects the environment, wildlife, and humanity.

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Home — Essay Samples — Science — Geology — Different Types of Volcanoes

Different Types of Volcanoes

• Categories: Geology

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Words: 618 |

Published: Mar 20, 2024

Words: 618 | Page: 1 | 4 min read

Table of contents

Shield volcanoes, stratovolcanoes, cinder cones, submarine volcanoes.

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Essay On The Volcano – 10 Lines, Short & Long Essay For Kids

Key Points To Remember When Writing An Essay On The Volcano For Lower Primary Classes

10 lines on the volcano for kids, a paragraph on the volcano for children, short essay on volcano in 200 words for kids, long essay on volcano for children, interesting facts about volcanoes for children, what will your child learn from this essay.

A volcano is a mountain formed through an opening on the Earth’s surface and pushes out lava and rock fragments through that. It is a conical mass that grows large and is found in different sizes. Volcanoes in Hawaiian islands are more than 4000 meters above sea level, and sometimes the total height of a volcano may exceed 9000 meters, depending on the region it is found. Here you will know and learn how to write an essay on a volcano for classes 1, 2 & 3 kids. We will cover writing tips for your essay on a volcano in English and some fun facts about volcanoes in general.

Volcanoes are formed as a result of natural phenomena on the Earth’s surface. There are several types of volcanoes, and each may emit multiple gases. Below are some key points to remember when writing an essay on a volcano:

• Start with an introduction about how volcanoes are formed. How they impact the Earth, what they produce, and things to watch out for.
• Discuss the different types of volcanoes and talk about the differences between them.
• Cover the consequences when volcanoes erupt and the extent of the damage on Earth.
• Write a conclusion paragraph for your essay and summarise it. 

When writing a few lines on a volcano, it’s crucial to state interesting facts that children will remember. Below are 10 lines on volcanoes for an essay for classes 1 & 2 kids.

• Some volcanoes erupt in explosions, and then some release magma quietly.
• Lava is hot and molten red in colour and cools down to become black in colour. 
• Hot gases trapped inside the Earth are released when a volcano erupts.
• A circle of volcanoes is referred to as the ‘Ring of Fire.’
• Volcano formations are known as seismic activities.
• Active volcanoes are spread all across the earth. 
• Volcanoes can remain inactive for thousands of years and suddenly erupt.
• Most volcanic eruptions occur underwater and result from plates diverging from the margins.
• Volcanic hazards happen in the form of ashes, lava flows, ballistics, etc.
• Volcanic regions have turned into tourist attractions such as the ones in Hawaii.

Volcanoes can be spotted at the meeting points of tectonic plates. Like this, there are tons of interesting facts your kids can learn about volcanoes. Here is a short paragraph on a volcano for children:

A volcano can be defined as an opening in a planet through which lava, gases, and molten rock come out. Earthquake activity around a volcano can give plenty of insight into when it will erupt. The liquid inside a volcano is called magma (lava), which can harden. The Roman word for the volcano is ‘vulcan,’ which means God of Fire. Earth is not the only planet in the solar system with volcanoes; there is one on Mars called the Olympus Mons. There are mainly three types of volcanoes: active, dormant, and extinct. Some eruptions are explosive, and some happen as slow-flowing lava.

Small changes occur in volcanoes, determining if the magma is rising or not flowing enough. One of the common ways to forecast eruptions is by analysing the summit and slopes of these formations. Below is a short essay for classes 1, 2, & 3:

As a student, I have always been curious about volcanoes, and I recently studied a lot about them. Do you know? Krakatoa is a volcano that made an enormous sound when it exploded. Maleo birds seek refuge in the soil found near volcanoes, and they also bury their eggs in these lands as it keeps the eggs warm. Lava salt is a popular condiment used for cooking and extracted from volcanic rocks. And it is famous for its health benefits and is considered superior to other forms of rock or sea salts. Changes in natural gas composition in volcanoes can predict how explosive an eruption can be. A volcano is labelled active if it constantly generates seismic activity and releases magma, and it is considered dormant if it has not exploded for a long time. Gas bubbles can form inside volcanoes and blow up to 1000 times their original size!

Volcanic eruptions can happen through small cracks on the Earth’s surface, fissures, and new landforms. Poisonous gases and debris get mixed with the lava released during these explosions. Here is a long essay for class 3 kids on volcanoes:

Lava can come in different forms, and this is what makes volcanoes unique. Volcanic eruptions can be dangerous and may lead to loss of life, damaging the environment. Lava ejected from a volcano can be fluid, viscous, and may take up different shapes. 

When pressure builds up below the Earth’s crust due to natural gases accumulating, that’s when a volcanic explosion happens. Lava and rocks are shot out from the surface to make room on the seafloor. Volcanic eruptions can lead to landslides, ash formations, and lava flows, called natural disasters. Active volcanoes frequently erupt, while the dormant ones are unpredictable. Thousands of years can pass until dormant volcanoes erupt, making their eruption unpredictable. Extinct volcanoes are those that have never erupted in history.

The Earth is not the only planet in the solar system with volcanoes. Many volcanoes exist on several other planets, such as Mars, Venus, etc. Venus is the one planet with the most volcanoes in our solar system. Extremely high temperatures and pressure cause rocks in the volcano to melt and become liquid. This is referred to as magma, and when magma reaches the Earth’s surface, it gets called lava. On Earth, seafloors and common mountains were born from volcanic eruptions in the past.

What Is A Volcano And How Is It Formed?

A volcano is an opening on the Earth’s crust from where molten lava, rocks, and natural gases come out. It is formed when tectonic plates shift or when the ocean plate sinks. Volcano shapes are formed when molten rock, ash, and lava are released from the Earth’s surface and solidify.

Types Of Volcanoes

Given below various types of volcanoes –

1. Shield Volcano

It has gentle sliding slopes and ejects basaltic lava. These are created by the low-viscosity lava eruption that can reach a great distance from a vent.

2. Composite Volcano (Strato)

A composite volcano can stand thousands of meters tall and feature mudflow and pyroclastic deposits.

3. Caldera Volcano

When a volcano explodes and collapses, a large depression is formed, which is called the Caldera.

4. Cinder Cone Volcano

It’s a steep conical hill formed from hardened lava, tephra, and ash deposits.

Causes Of Volcano Eruptions

Following are the most common causes of volcano eruptions:

1. Shifting Of Tectonic Plates

When tectonic plates slide below one another, water is trapped, and pressure builds up by squeezing the plates. This produces enough heat, and gases rise in the chambers, leading to an explosion from underwater to the surface.

2. Environmental Conditions

Sometimes drastic changes in natural environments can lead to volcanoes becoming active again.

3. Natural Phenomena

We all understand that the Earth’s mantle is very hot. So, the rock present in it melts due to high temperature. This thin lava travels to the crust as it can float easily. As the area’s density is compromised, the magma gets to the surface and explodes.

How Does Volcano Affect Human Life?

Active volcanoes threaten human life since they often erupt and affect the environment. It forces people to migrate far away as the amount of heat and poisonous gases it emits cannot be tolerated by humans.

Here are some interesting facts:

• The lava is extremely hot!
• The liquid inside a volcano is known as magma. The liquid outside is called it is lava.
• The largest volcano in the solar system is found on Mars.
• Mauna Loa in Hawaii is the largest volcano on Earth.
• Volcanoes are found where tectonic plates meet and move.

Your child will learn a lot about how Earth works and why volcanoes are classified as natural disasters, what are their types and how they are formed.

Now that you know enough about volcanoes, you can start writing the essay. For more information on volcanoes, be sure to read and explore more.

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Volcano Hazards Program

Find u.s. volcano.

There are about 170 potentially active volcanoes in the U.S. The mission of the USGS Volcano Hazards Program is to enhance public safety and minimize social and economic disruption from volcanic unrest and eruption through our National Volcano Early Warning System. We deliver forecasts, warnings, and information about volcano hazards based on a scientific understanding of volcanic behavior.

Volcano Activity Notifications

USGS Volcano Observatories release regular updates and notifications to communicate increases or decreases in volcanic activity and explain unusual or hazardous circumstances. 

Volcano Hazards Assessments

Long-term hazards assessments identify locations at risk from volcanic hazards. They are released as high-resolution hazards-zonation maps with accompanying explanations, which help guide eruption preparedness plans.

U.S. Volcano Observatories

Volcano Observatory staff monitor, research, and issue formal notices of activity for volcanoes in assigned geographic areas. Scientists also assess volcano hazards and work with communities to prepare for volcanic eruptions.

• Alaska Volcano Observatory (AVO)
• USGS California Volcano Observatory (CalVO)
• USGS Cascades Volcano Observatory (CVO)
• USGS Hawaiian Volcano Observatory (HVO)
• Yellowstone Volcano Observatory (YVO)

Volcano Watch — A decade later, remembering the Pāhoa lava flow crisis

Photo and video chronology - images of the june 3 fissure eruption from kīlauea's southwest rift zone, volcano watch — keeping up with kīlauea, publications, yellowstone volcano observatory 2023 annual report, origins and nature of large explosive eruptions in the lower east rift zone of kīlauea volcano, hawaii: insights from ash characterization and geochemistry, explosive 2018 eruptions at kīlauea driven by a collapse-induced stomp-rocket mechanism.

• Earth Science

Volcano Eruption

Volcanoes are ruptures in the crust of our planet Earth that allow hot gases, molten lava and some rock fragments to erupt by opening and exposing the magma inside. In this piece of article, we will be discussing how and why volcanoes erupt.

How Do Volcanoes Erupt?

It is so hot deep within the earth that some rocks slowly melt and turn into a thick flowing matter known as magma. Since it is lighter than solid rock, the magma rises and collects in magma chambers. Eventually, some magma pushes through fissures and vents on the earth’s surface. Hence, a volcanic eruption occurs, and the erupted magma is known as lava.

We need to understand the Earth’s structure to know how volcanoes erupt. At the top lies the lithosphere, the outermost layer that consists of the upper crust and mantle. The thickness of the crust ranges from 10km to 100km in mountainous locations and mainly consists of silicate rock.

See the video below to know more about the causes of volcanic eruptions.

Why Do Volcanoes Erupt?

The Earth’s mantle within the crust is classified into different sections depending on individual seismology. These include the upper mantle, which ranges between 8 – 35 km to 410 km; the transition zone ranges from 400 to 660 km; the lower mantle lies between 660 – 2891 km.

The conditions change dramatically from the crust to the mantle location. The pressures rise drastically and temperatures rise up to 1000 o C. This viscous and molten rock gets collected into large chambers within the Earth’s crust.

Since magma is lighter than surrounding rock, it floats up towards the surface and seeks out cracks and weakness in the mantle. It finally explodes from the peak point of a volcano after reaching the surface. When it is under the surface, the melted rock is known as magma and erupts as ash when comes up.

Rocks, lava and ash are built across the volcanic vent with every eruption. The nature of the eruption mainly depends on the viscosity of the magma. The lava travels far and generates broad shield volcanoes when it flows easily. When it is too thick, it makes a familiar cone volcano shape. If the lava is extremely thick, it can build up in the volcano and explode, known as lava domes.

Causes of Volcanic Eruption

We know that the mantle of the Earth is too hot, and the temperature ranges from 1000° Celsius to 3000° Celsius. The rocks present inside melt due to high pressure and temperature. The melted substance is light in weight. This thin lava comes up to the crust since it can float easily. Since the density of the magma between the area of its creation and the crust is less than the enclosed rocks, the magma gets to the surface and bursts. The magma is composed of andesitic and rhyolitic components along with water, sulfur dioxide, and carbon dioxide in dissolved form. By forming bubbles, excess water is broken up with magma. When the magma comes closer to the surface, the level of water decreases and the gas/magma rises in the channel. When the volume of the bubbles formed is about 75%, the magma breaks into pyroclasts and bursts out. The three main causes of volcanic eruptions are: The buoyancy of the magma Pressure from the exsolved gases in the magma Increase in pressure on the chamber lid Hope you are familiar with why volcanoes erupt and the cause of the volcanic eruption. Stay tuned to BYJU’S to learn about types of volcanoes, igneous rocks, and much more.

Frequently Asked Questions – FAQs

What is lava.

When a volcanic eruption occurs, the erupted magma is known as lava.

State true or false: The nature of the eruption mainly depends on the viscosity of the magma.

What are the causes of volcanic eruption.

The causes of the volcanic eruption are:

• The buoyancy of the magma
• Pressure from the dissolved gases in the magma
• Increase in pressure on the chamber lid

Define magma.

How is earth’s mantle classified.

• The upper mantle – ranges between 8 – 35 km to 410 km
• Transition zone ranges from 400 to 660 km
• Lower mantle lies between 660 – 2891 km

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Volcanic Eruptions

• Cause and Effect
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Cause and Effects of Volcanic Eruptions

Introduction There are over 20 active volcanos left in the world today. Have you ever wondered or learned about what causes a volcano? Volcanic eruptions can be a huge deal for the environment and the people around it. What causes do volcanos have on the environment and what cause does it have on the people? Well the truth is, the causes of active volcanos there are today, do have effects on its surroundings.

What is a volcano, and what causes it to erupt? Volcanoes occur at weak points in the Earth’s crust. The outer layer, known as the Lithosphere, of the earth includes the hard crust. The earth is made up of huge plates, these plates shift gradually over a time period of millions of years. The weak points in the crust are located along regions where the plates meet, and also in spots under the sea, these areas are known as ‘hot spots’. A volcano is an opening in the earth’s crust often formed like a mountain, which opens downward to a pool of molten rock below the surface of the earth. When pressure is built up inside this pool, eruptions can occur. Volcanoes are formed when magma from underneath the earth’s upper mantle, part of the crust, works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger because the lava that flows over the top produces a new layer of earth. Lava and ash shoot up through the opening, and burst over the top or fill the air with lava fragments and ash. There have been around 1500 total calculated volcanos since the first recordings in history. Today there remains less than 30 total active in the world now (“Natural Disasters”).

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What affects to volcanos place on the climate? To start when a volcano erupts, it causes an effect on the global climate. A large number of volcanic ash and volcanic gases are emitted into the air and cause a great impact on the climate. After a volcanic eruption the local weather will be dark and stormy, and the eruption can even cause mud rain for several months. Volcanic ash and volcanic gas is sprayed into sky and reaches high altitudes. These volcanic materials will cover the sun, causing temperatures to drop. Along with causing damage climate volcanoes damage the climate. Volcanoes emit large amounts of ash in the air. This volcanic ash and rain combine to form and cause flooding that can wash away roads, bridges, and can even flood nearby villages and cities, leaving many people homeless and destroying everything in its path. Soil, rock, and debris forming together can pile up like a flood and leave cities swamped. Also the gases emitted from the volcanic eruption are really bad for the air which us people have to breathe in. This could cause serious health issues for people only with heart or respiratory problems.

If the contents in the air, sulfur dioxide, hydrogen sulfide, and hydrogen fluoride, combine with sulfuric acid it can damage a person’s skin. (“Climate Effects of Volcanic Eruptions”). Volcanic eruptions have a major impact of the natural landscape of the earth. Land is the world’s most valuable resource. Land is wear millions and millions of plant species grow. Volcanic ash can have a good effect on the environment. Volcanic ash is filled with nutrients that make the soil more fertile which helpful for any potential farmers located around the volcano. However, were ever the lava hardens and turns into rock on the earth will make for useless ground for farmers and anyone else looking to use the land. The rock will take thousands of years to turn back into dirt and become useful. Also, even though it’s a small percentage, the ash from the volcanic eruption makes up 1% of earth’s surface. Volcanoes affect people in many ways, some are good, and others are not. 200,000 people have been reported dead due to a volcanic eruption in the past 500 years. The worst recorded volcanic disaster was believed to cause over 92,000 casualties from falling ash and other related causes. 100,000 more deaths were believed to be caused from starvation in the area. Other ways that volcanos effect people in bad ways are that their houses, buildings, roads, and fields can get covered with ash. Houses and buildings may not always collapse, but often the people affected by the volcano leave because of the ash, and are not there to get the ash off of their roofs. When the raining ash is really heavy, or wet, it can become impossible for people to breathe. People are not going to chased down by flowing lava, but the lava will possibly destroy and certainly run over houses, roads, and any other structures. The only real good affect a volcano has for a human is if you are a farmer. Volcanic ash landing a farmer’s field will produce very rich soils. Volcanos also attract many tourists, which in return brings a lot of jobs to the area. Also once it erupts; if you search within the volcano you can find metallic minerals such as zinc, lead, and even gold. A volcanic eruption will also make for a great scene. It’s not every day a person can watch hot fiery lava bursting into air making for magnificent photos (“How Do Volcanoes Affect People?”). What causes volcanos produces great effects towards many different things. Humans, weather, land, buildings, and even the atmosphere are affected by a volcanic eruption. Volcanos can be good but also bad for humans and the environment. And so it is true, the causes of active volcanos there are today, do have effects on its surroundings.

“Climate Effects of Volcanic Eruptions.” N.p., n.d. Web. 6 Dec. 2012. “Natural Disasters.” ThinkQuest. Oracle Foundation, n.d. Web. 06 Dec. 2012. Decker, R. & B. “How Do Volcanoes Affect People?” Volcano World. Oregon State, 1989. Web. 6 Dec. 2012.

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137 Intriguing Cause & Effect Essay Topics for Students

Teach critical thinking, logic, and the art of persuasion.

Cause-and-effect essays aren’t just a way to help students strengthen their writing skills. They’ll also learn critical thinking, logic, and the art of persuasion. In addition, they teach students to demonstrate how one thing directly influences another. Coming up with engaging cause-and-effect essay topics can be challenging, but we have you covered. This list of ideas includes a variety of topics that range from social and cultural movements to mental health and the environment.

Science and Environment Cause & Effect Essay Topics

• Describe the effect of urbanization on the environment.
• What is the impact of air pollution on health?
• What are the causes and consequences of plastics on marine life?
• What is the impact of rising sea temperatures on fish and marine life?
• Describe the impact of human behavior on global warming.

• What is the effect of social media on environmentalism?
• What causes volcanic eruptions?
• What causes trees to die?
• What are the effects of gravity?
• Why are plants green?
• Why do trees shed their leaves?
• What causes a species to become endangered?
• What are some of the causes of animals losing their habitats?
• Describe the effect of overpopulation on the environment.
• What are the effects of famine on human population?
• What are the causes and effects of Antarctica floods?
• What are the effects of pollution on the ocean?
• What effect do cars have on the environment?
• Why is it important to manage wildfires?
• What has been the impact of DNA on crime scene processing?

• What are the impacts of deforestation in Brazil?
• What are the effects of GMO foods on human health?
• What are the impacts of immunizations on human health?

Technology and Social Media Cause & Effect Essay Topics

• What are the effects of social media on adolescent development?
• How does technology affect productivity?
• What are the effects of video games on childhood development?
• How do cell phones affect human relationships?
• What are some reasons a teacher might ban cell phones from class?

• What effects do cell phones have on sleep?
• What effects did the invention of the Internet have on technology?
• What were the origins of cyberbullying?
• What are the effects of tablet use on small children?
• How has online dating changed relationships?
• What makes some people less likely to use social media?
• What are the effects of social media on privacy?
• How does the rise of TikTok affect Facebook and Instagram?
• In what ways could social media lead to extremism?
• What is the impact of social media on the increasing popularity of plastic surgery and other enhancements?

• What are some of the benefits of owning a smartphone and what are some of the drawbacks?
• What has been the impact of online shopping on brick-and-mortar stores?
• What has been the impact of smartphones on marriages and relationships?
• What are the causes and effects of texting while driving?
• What has the rise of “influencers” meant for Hollywood?
• In what ways have photo filters influenced young people’s self-esteem?

Culture and Social Issues Cause & Effect Essay Topics

• What are some of the reasons for substance abuse in young people?
• What are some of the effects of bullying?
• How does economic status affect the quality of health care?
• What are some of the causes of homelessness?
• Explain the effects of ignorance on discrimination.
• What are the impacts of death sentences on social justice?

• How does financial success affect societal privilege?
• What effects does growing up poor have on children?
• In what ways does religion influence society?
• What are the effects of immigration on a host country?
• What are the effects of ageism on job opportunities?
• What is the impact of LGBTQ+ representation in TV and movies?
• What are the effects of school shootings on politics?
• How do school uniforms affect students?
• What are the impacts of high student debt?
• What are the impacts of body shaming on people?
• What were the lasting impacts of the AIDS epidemic on society?

• What impact does banning abortion have in the United States?
• What has been the impact of marriage equality in the United States?
• What are the causes and effects of noise pollution?
• What are the causes and effects of inflation on the economy?
• What are the effects of TV shows on our behavior?

Sports Cause & Effect Essay Topics

• Examine the effects of exercise on mental health.
• What led to baseball being an iconic American sport?
• What drives people to participate in extreme sports?
• In what ways did globalization affect modern sports?
• What were the effects of doping on amateur and professional sports?
• Select a sport and write about the historical factors that led to the popularization of that sport.

• Describe the ways in which youth sports influence a child’s development.
• What were the driving forces behind the first Olympics?
• How can team sports help develop social skills?
• How have e-sports changed the sporting landscape?
• In what ways do race biases influence sports?

• What are the effects of regular workouts on immunity?
• How does participating in sports affect leadership skills?
• In what ways can sports lead to character development?
• What effect does famous athletes’ social commentary have on their fans?

History Cause & Effect Essay Topics

• What are the effects of the war in Syria on the United States?
• What have been the lasting effects of the Civil Rights Movement?
• What were the causes and effects of the attack on Pearl Harbor?
• What led up to the Berlin Wall being torn down and what effects did that have?

• What lasting impact did 9/11 have on modern American society?
• What were the causes of the Salem Witch Trials?
• What was the cultural impact of the Spanish-American War?
• How has globalization led to modern-day slavery?
• What events led to the fall of the Roman Empire?
• What were the impacts of the Great Depression on women’s employment?
• How did cartels come into existence? What effect have they had on the United States and Mexico?
• What were the causes and effects of the Women’s Liberation Movement?
• Give an example of colonialism in history and name the resulting impact to the affected society.

• What led to the rise of ISIS and what has the impact been on international security?
• What factors led to the Titanic’s sinking?
• What were the causes and effects of the Vietnam War?
• Choose an American president. What led him to become president and what were the effects of his presidency?

Mental Health Cause & Effect Essay Topics

• How can stress affect the immune system?
• How does social anxiety affect young people?
• How can high academic expectations lead to depression?
• What are the effects of divorce on young people?
• How does service in the armed forces lead to post-traumatic stress disorder?

• What are the effects of mindfulness on mental health?
• Describe the ways in which the COVID-19 pandemic has impacted mental health.
• How does childhood trauma impact childhood development?
• What impact does witnessing violence have on mental health?
• What is behind increasingly high levels of anxiety in modern American society?

• What are the causes and effects of panic attacks?
• What are the causes and consequences of high stress in the workplace?
• What are some of the causes of insomnia and in what ways does it affect mental health?
• What is the impact of staying home for an extended period of time?

Current Events Cause & Effect Essay Topics

• Choose a local public education campaign. What are the effects of that campaign?
• What are the causes and effects of migration?
• What are the causes and effects of terrorist attacks?

• What are the effects of legalizing genetic engineering research?
• How do low voting rates impact elections and government?
• What is the effect of raising the minimum wage?
• What are the effects of globalization on society?
• How does gerrymandering affect election outcomes?
• What are the causes and effects of police brutality?
• What are the causes and effects of political polarization?

• What are the causes and effects of fake news?
• What are the effects of global war on citizens?
• What is the effect of international aid on poverty or health?
• Why do some countries have nuclear weapons, and what does this mean for other countries?

Education Cause & Effect Essay Topics

• What are the effects of teacher quality on student success?
• What are the causes and effects of student loan debt?
• What are the causes and effects of low graduation rates?

• What are the effects of assigning homework?
• What are the causes and effects of school funding disparities?
• What are the causes and effects of the digital divide in education?
• What is the effect of AI on education?
• What are the causes and effects of student burnout?
• Should students be required to study a foreign language in school, and what are the effects of learning a foreign language?

• What effect has the COVID pandemic had on education?
• What are the effects of same-sex classrooms or schools?

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Cones Volcanoes and their Unexpected Role in Fictional World-Building

This essay is about cone volcanoes, also known as cinder cones, and their role in fictional world-building. It explores how these rapidly forming geological structures, characterized by their steep, conical shapes, can serve as significant plot elements in stories. The essay highlights the dramatic and sudden formation of cone volcanoes, their impact on landscapes and communities, and their potential as symbols of change and renewal. It also discusses how the fertile soils created by volcanic activity can transform barren lands and how the cultural and historical significance of these volcanoes can enrich narratives. Cone volcanoes offer both scientific intrigue and dramatic potential, making them valuable for creating dynamic and engaging fictional worlds.

How it works

Cone volcanoes, with their steep, conical forms and rapid growth, are among the most fascinating geological phenomena on Earth. Yet beyond their physical presence and scientific intrigue, these dynamic natural features offer a rich source of inspiration for fictional world-building, providing a backdrop of both creation and destruction that can add depth and drama to any narrative.

Cone volcanoes, or cinder cones, are formed through explosive volcanic eruptions that propel fragments of lava into the air. These fragments, including cinders, ash, and volcanic bombs, fall back around the vent and build up the distinctive cone shape.

This rapid formation process, which can take mere weeks or months, contrasts sharply with the slow and steady growth of larger volcanoes like shield volcanoes and stratovolcanoes. The dramatic birth of a cone volcano can be a central event in a fictional story, symbolizing sudden change or upheaval in the world.

Imagine a fictional world where cone volcanoes are not just geological formations but also key elements in the lives and cultures of the inhabitants. In such a world, the sudden appearance of a cone volcano could be seen as an omen, a harbinger of significant change, or a divine act. The eruption could bring both destruction and new opportunities, shaping the land and the lives of the characters in profound ways.

Consider the example of Paricutin, a real-world cone volcano in Mexico that erupted in 1943, surprising locals with its rapid growth. In a fictional setting, such an eruption could be the catalyst for a dramatic storyline. A peaceful village might find itself at the epicenter of a new volcano, forcing the residents to confront the power of nature. The eruption could disrupt daily life, destroy homes, and challenge the community’s resilience. Yet, it could also lead to discoveries of valuable minerals in the volcanic soil, sparking a rush of fortune-seekers and transforming the village into a bustling town.

The layers of volcanic ash, cinders, and bombs that make up a cone volcano tell a story of its eruptive history. Each layer represents a different phase of activity, with variations in the size and composition of the materials reflecting changes in the eruption’s intensity. In a fictional narrative, these layers could hold clues to the past, secrets buried beneath the surface that characters must uncover. Perhaps ancient artifacts or long-lost treasures are entombed within the volcano, waiting to be discovered by intrepid explorers.

The ecological impact of cone volcanoes can also play a significant role in a fictional world. The volcanic materials they expel are rich in minerals, creating fertile soils that support lush vegetation. This transformation from barren land to fertile ground could symbolize renewal and rebirth in the story. Characters might struggle to adapt to the new landscape, finding ways to cultivate crops and rebuild their lives in the shadow of the volcano. The fertile soil could attract settlers, leading to conflicts over land and resources, and driving the plot forward.

Cone volcanoes are also natural laboratories for scientists, offering opportunities to study volcanic processes and hazards. In a fictional context, this scientific aspect could be woven into the narrative. Characters might include volcanologists or geologists, whose research and discoveries play a crucial role in understanding and predicting volcanic activity. Their efforts could be vital in preventing future disasters, adding an element of tension and urgency to the story.

Cultural and historical significance is another aspect of cone volcanoes that can enrich a fictional world. In many regions, these volcanoes are woven into local folklore and history, representing both the destructive and regenerative powers of nature. Stories and legends associated with cone volcanoes could be an integral part of the world-building, reflecting the beliefs and traditions of the inhabitants. Characters might draw on these stories for guidance, finding meaning and purpose in the ancient tales as they navigate the challenges posed by the volcano.

Despite their smaller size, cone volcanoes can pose significant hazards. Their eruptions can be highly explosive, producing dangerous pyroclastic flows, ashfall, and lava bombs. These hazards can create dramatic and perilous situations for characters, testing their courage and ingenuity. The threat of an imminent eruption could drive the narrative, as characters race against time to evacuate, save loved ones, or find a way to mitigate the disaster.

The artistic and cultural allure of cone volcanoes can also be a source of inspiration in a fictional world. The stark, dramatic landscapes they create might inspire artists, writers, and musicians within the story, adding a layer of cultural richness. The volcano could become a symbol in the world’s art and literature, representing themes of creation, destruction, and rebirth.

In addition to their narrative potential, cone volcanoes can serve as settings for tourism and adventure in a fictional world. Characters might embark on expeditions to explore the volcanic terrain, discovering hidden caves, unique flora and fauna, and breathtaking vistas. The volcano could be a destination for thrill-seekers, drawn by the challenge and beauty of the volcanic landscape.

In conclusion, cone volcanoes are a captivating and versatile element for fictional world-building. Their rapid formation, distinctive shape, and dramatic impact on the landscape and its inhabitants provide a rich tapestry of possibilities for storytelling. From the sudden birth of a volcano to the fertile soils it leaves behind, cone volcanoes can symbolize change, challenge, and renewal, offering endless inspiration for creating compelling and dynamic fictional worlds.

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