what is a volcano eruption essay

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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Volcanic eruptions.

Photo by R.E. Stinson.

Introduction

Volcanic eruptions are among the most awesome of all natural phenomena on Earth. They may be strangely beautiful as fountains of glowing-red lava rise above a vent to feed a lava flow that spreads rapidly downhill. Or they may consist of terrifying explosions that send clouds of scorching hot ash high into the atmosphere or roaring down a volcano’s slopes and destroying everything in its path. While a great range in the type, style, and violence of volcanic eruptions exists, they all are part of one of the most fundamental geologic processes that builds and shapes Earth’s crust. The place to begin an exploration of the diversity of the different types and kinds of volcanic eruptions is with the definition. A volcanic eruption is the expulsion of gases, rock fragments, and/or molten lava from within the Earth through a vent onto the Earth’s surface or into the atmosphere.

USGS illustration.

Some volcanic eruptions consist of mostly gas emissions, others are relatively quiet discharges of fluid lava, and yet others are cataclysmic explosions. Different kinds of eruptions leave characteristic deposits that, in turn, build different types of volcanoes. A magma’s composition, viscosity, and gas content, the eruption rate, and the size of the magma reservoir determines many aspects of eruptions, including how explosive they are. National parks are great places to observe current volcanic activity.

• Kilauea in Hawai’i Volcanoes National Park was active from 1983 to 2018, and has had shorter periods of eruption since then.
• Katmai National Park and Preserve in Alaska is one of the world’s most active volcanic areas with 10 volcanoes that have had historic eruptions.
• The most recent eruption at the Lassen volcanic center in California occurred in 1917.

A number of other national parks contain volcanoes that have had prehistoric eruptions. Volcanoes in many other parks erupted in the even more distant past. Today, these mountains evoke peace and serenity that belies the violence in their history.

• Mount Mazama exploded about 7,550 years ago to form Crater Lake.
• Capulin Volcano erupted just over 54,000 years ago.
• The Valdez Caldera erupted 1.25 million years ago.

Whether active or ancient, volcanic landforms found in national parks result from their eruption dynamics, with the volcanoes themselves and the lava flows and other deposits they leave behind serving as tangible evidence of the volcanic processes that formed them.

Generation and Rise of Magma

The melted rock (magma) that is erupted in volcanoes does not come from the Earth’s core or even from deep within the mantle. There are also no permanent pools of melted rock found within the crust or mantle. Instead, magma produced from partial melting of the upper mantle. The heat that causes the partial melting comes from several sources; most importantly, from decay of radioactive elements, such as uranium, thorium, and potassium. Once magma is generated, it rises buoyantly because it is lighter than the surrounding rock. It moves in slow-moving balloons or diapirs; or in planar fractures (dikes). Sometimes it pools at the base of the crust, and other times it continues to rise to form magma chambers. Shallow magma chambers may form in regions of neutral buoyancy, i.e., areas where the pressure within the magma body equals the pressure outside it. Magma typically begins to crystallize while they are being stored in magma chambers, forming a liquid-crystal mush. Eruptions from a shallow magma body may be triggered by injection of more magma into the chamber, by overpressure from increased volatile (gas) content, or by some other factor.

Composition & Viscosity

Volcanic eruptions are inherently physical processes given that they are the emission of gas, magma, and rock from within the Earth. Yet many aspects of eruptions are actually controlled by magma chemistry. In fact, the composition of the magma, as well as its gas content, largely determines whether an eruption is explosive, and the magnitude of that explosivity. Magma composition impacts nearly everything about a volcano, with viscosity of the melt being one of the most important factors that determines eruption dynamics, and even the shape of a volcanic edifice. Viscosity is the internal friction, or resistance to flow—or how “thick and sticky” or “thin and runny” a lava is.

• Lavas with low viscosity such as those erupted at Kilauea in Hawai’i Volcanoes National Park flow easily, with flow fronts that move up to 6 miles (10 km) per hour. Speeds in channels or lava tubes on steep slopes can be as fast as 19 miles (30 km) per hour.
• Highly viscous lavas do not spread out to form wide lava flows, but instead form steep-sided domes immediately above a vent, such as the dome at Novarupta in Katmai National Park .

Modified from NASA illustration.

Silica (SiO2) content has the greatest impact on magma viscosity. Most igneous rocks are made predominately of silica with concentrations ranging from about 45 to 78% by weight. Specifically, silica is arranged in tetrahedrons (Si04 complexes). Silica tetrahedrons can share oxygen atoms to form chains or networks in a melt. Higher concentrations of silica leads to longer and more complex chains. The greater abundance of complex chains of silica tetrahedrons have a greater propensity to tangle with one another. This impedes their ability to flow past one another, somewhat akin to tangling of long strands of spaghetti.

Therefore, the general rule is that magmas with high silica content are highly viscous, and ones with low silica have low viscosity (e.g., are inviscid ). The presence of other elements, particularly sodium and potassium, can lower viscosity in rhyolitic magmas because they interfere with silica’s ability to form complex chains. Similarly, the presence of water in the melt (which is common) can also decrease viscosity. In general the viscosity of a low silica magma like basalt is thousands of times more viscous than liquid water. High silica melts can be many orders of magnitude more viscous than basalts. Their relatively low viscosities are why basalts are generally extruded in quiet (effusive) or mildly explosive eruptions. On the other hand, eruptions of high silica magmas are likely to be explosive (due to both high viscosity and higher gas content).

NPS photo by B. Seibert.

Photo by Lanny Simpson, Alaska High Mountain Images.

Gas content & exsolution

Courtesy of James St. John (Flickr)

Magmas typically contain small amounts of dissolved gas ( volatiles ). Water and carbon dioxide are the most common volatiles, although sulfur dioxide, hydrogen sulfide, and others may be present. Until a magma nears the Earth’s surface, the enormous pressure of the overlying rock keeps gases dissolved. Near the surface, the pressure decreases and they can exsolve from the melt, ultimately forming gas bubbles in a process called vesiculation . This exsolution of magmatic gases as a magma ascends towards the surface is one of the forces that propels volcanic eruptions. The release of pressure as a magma nears the Earth’s surface is similar to the release of pressure in a carbonated beverage when it is opened. The exsolution of carbon dioxide from soda pop due to the release of confining pressure when the can is opened is like the expansion and exsolution of gases that propels eruptions. Higher volatile contents increase the likelihood of explosive eruptions compared to eruptions of magma with lower concentrations of gases. Viscosity is also important because gases can escape more easily from thin fluids than thick ones, as can be observed in the spattering that can happen when making jam (a more viscous liquid) versus the simple boiling of water. In general, the higher the viscosity and the higher the gas content, the more explosive the eruption will be.

USGS photo.

• In the eruptions that build some cinder cones, the vesiculation of basaltic magma from expanding and exsolving gas throws blobs of magma perhaps tens to hundreds of feet into the air that then cool and fall around the vent as cinders.
• In highly explosive eruptions of silicic magmas, vesiculation can completely shatter the erupting material into tiny bits called volcanic ash in columns that rise tens of thousands of feet into the atmosphere. For example, the April 21, 1989 eruption of Redoubt Volcano in Lake Clark National Park and Preserve formed an eruption column that ascended to a height of 62,000 feet (19 km).

Rate of Eruption

The rate of eruption can also influence how explosive an eruption is. If magma ascends slowly from deep within the crust, it is possible for the dissolved gases to escape nonviolently over time. But when magma ascension and eruption rate is rapid, the dissolved gases must escape all at once and the eruption is more explosive. Likewise, a soda gently fizzes when the gases dissolved in it are slowly released. Yet it explodes violently when carbon dioxide exsolves rapidly, such as happens after a can is shaken. It is the sudden release of energy by gas under pressure by rapid exsolution that is one of the main drivers of explosive eruptions.

Size of Magma Reservoir

The size of the magma body beneath a volcano has a strong controlling factor in the magnitude of eruptions because the availability of magma can strongly constrain its size. Small magma bodies simply cannot sustain large eruptions because there is not enough material available. Cinder cones, even exceptionally large ones like Sunset Crater Volcano, only tap small magma sources. The volume of erupted rock material erupted In 1085 CE to form Sunset Crater Volcano about was 0.12 cubic miles (0.52 cubic km) in volume in contrast to the largest eruption at Yellowstone 2.1 million years ago that expelled nearly 600 cubic miles (2,450 cubic km) of material.

Volcanic Activity

An erupting volcano may include varying types of activity, along with a range of intensity. Volcanic activity includes earthquakes caused by magma movement, gas emissions, effusive emissions of lava, and cataclysmic eruptions. Most geologists use the term eruption to encompass a whole period of volcanic activity which is bracketed by quiet intervals. The Smithsonian Institute has set an arbitrary interval of three months of complete inactivity of a volcano to separate one eruption from another. Eruptions generally consist of eruptive pulses and eruptive phases.

• Eruptive pulses are single explosions that may last a few seconds to minutes.
• Eruptive phases consist of numerous eruptive pulses that generate a pulsating eruptive column or lava flow, and may last from a few hours to days.

An eruption may consist of many eruptive pulses and last a few days, months, or even years.

Active, Dormant & Extinct

Volcanologists describe volcanoes as being active, dormant, or extinct based on how recently they erupted and whether they are likely to do so again.

• Active : A volcano is considered potentially active if it has erupted during the last 10,000 years. Some volcanoes may have dormant periods between eruptions greater than 10,000 years, but 10,000 years is a convenient cut-off date for activity and is used by convention. An active volcano is currently erupting, or is one that has erupted in historic time. Even though Mount Rainier hasn’t had a significant eruption for a thousand years, it is considered to be an active volcano.
• Dormant : A volcano that is not erupting now, but is considered likely to erupt in the future. There is no precise distinction between active and dormant volcanoes. Sometimes dormant volcanoes are described as being potentially active. Mount Rainier and the El Malpais National Monument volcanic field are considered dormant.
• Extinct : An extinct volcano is one that is not expected to erupt again in the future. Sometimes the determination of whether a volcano is extinct is based on the amount of time since its last eruption. Alternatively, some types of volcanoes such as cinder cones typically only erupt once. For example, Capulin Volcano, a cinder cones, is extinct.

Last updated: July 18, 2022

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.

For Hungry Minds

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.”

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November 29, 1999

What Causes a Volcano to Erupt, and How Do Scientists Predict Eruptions?

Volcanologists cannot yet predict a volcanic eruption

By Attila Kilinc

Kilauea erupting.

Douglas Peebles Getty Images

Editor’s Note (6/4/18): This story is being re-posted in light of the deadly eruption of Guatemala’s Fuego volcano on Sunday (June 3), which covered nearby villages in fast-moving ash flows.

Attila Kilinc, head of the geology department at the University of Cincinnati, offers this answer. Most recently, Professor Kilinc has been studying volcanoes in Hawaii and Montserrat.

When a part of the earth's upper mantle or lower crust melts, magma forms. A volcano is essentially an opening or a vent through which this magma and the dissolved gases it contains are discharged. Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber. What follows is a brief description of these processes.

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As rock inside the earth melts, its mass remains the same while its volume increases--producing a melt that is less dense than the surrounding rock. This lighter magma then rises toward the surface by virtue of its buoyancy. If the density of the magma between the zone of its generation and the surface is less than that of the surrounding and overlying rocks, the magma reaches the surface and erupts.

Magmas of so-called andesitic and rhyolitic compositions also contain dissolved volatiles such as water, sulfur dioxide and carbon dioxide. Experiments have shown that the amount of a dissolved gas in magma (its solubility) at atmospheric pressure is zero, but rises with increasing pressure.

For example, in an andesitic magma saturated with water and six kilometers below the surface, about 5 percent of its weight is dissolved water. As this magma moves toward the surface, the solubility of the water in the magma decreases, and so the excess water separates from the magma in the form of bubbles. As the magma moves closer to the surface, more and more water exsolves from the magma, thereby increasing the gas/magma ratio in the conduit. When the volume of bubbles reaches about 75 percent, the magma disintegrates to pyroclasts (partially molten and solid fragments) and erupts explosively.

The third process that causes volcanic eruptions is an injection of new magma into a chamber that is already filled with magma of similar or different composition. This injection forces some of the magma in the chamber to move up in the conduit and erupt at the surface.

Although volcanologists are well aware of these three processes, they cannot yet predict a volcanic eruption. But they have made significant advances in forecasting volcanic eruptions. Forecasting involves probable character and time of an eruption in a monitored volcano. The character of an eruption is based on the prehistoric and historic record of the volcano in question and its volcanic products. For example, a violently erupting volcano that has produced ash fall, ash flow and volcanic mudflows (or lahars) is likely to do the same in the future.

Determining the timing of an eruption in a monitored volcano depends on measuring a number of parameters, including, but not limited to, seismic activity at the volcano (especially depth and frequency of volcanic earthquakes), ground deformations (determined using a tiltmeter and/or GPS, and satellite interferometry), and gas emissions (sampling the amount of sulfur dioxide gas emitted by correlation spectrometer, or COSPEC). An excellent example of successful forecasting occurred in 1991. Volcanologists from the U.S. Geological Survey accurately predicted the June 15 eruption of the Pinatubo Volcano in the Philippines, allowing for the timely evacuation of the Clark Air Base and saving thousands of lives.

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Explainer: the volcano basics.

All volcanoes are not alike, but all do deserve respect

An ash burst coming from Washington’s Mount St. Helens in May 1982.

Lyn Topinka/ USGS

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By Sid Perkins

October 1, 2014 at 12:57 pm

A volcano is a spot in Earth’s crust where molten rock, volcanic ash and certain types of gases escape from an underground chamber. Magma is the name for that molten rock when it’s below ground. Scientists call it lava once that liquid rock erupts from the ground — and may start flowing across Earth’s surface. (It’s still “lava” even after it’s cooled and solidified.)       

Roughly 1,500 potentially active volcanoes exist across our planet, according to scientists at the U.S. Geological Survey, or USGS. About 500 volcanoes have erupted since humans have been keeping records.

Of all volcanoes that have erupted in the past 10,000 years, roughly 10 percent reside in the United States. Most of them exist in Alaska (particularly in the Aleutian Island chain), in Hawaii and in the Cascade Range of the Pacific Northwest.  

But volcanoes are not just an Earthly phenomenon. Several large volcanoes rise above the surface of Mars. Mercury and Venus both show signs of past volcanism. And the most volcanically active orb in the solar system is not Earth, but Io. It’s the innermost of the four largest moons of Jupiter. Indeed, Io has more than 400 volcanoes, some of which spew plumes of sulfur-rich material 500 kilometers (about 300 miles) into space.

(Fun fact: The surface of Io is small, only about 4.5 times the area of the United States. So its volcano density would be about comparable to 90 continuously active volcanoes erupting across the United States.)

Where do volcanoes form?

Volcanoes can form on land or below the sea. Indeed, Earth’s biggest volcano lies submerged a mile below the ocean’s surface. Certain spots on our planet’s surface are especially susceptible to volcano formation.

Most volcanoes, for instance, form at or near the edges — or boundaries — of Earth’s tectonic plates . These plates are large slabs of crust that jostle and scrape past each other. Their movement is driven largely by the circulation of the scalding, liquid rock in Earth’s mantle. That mantle is thousands of kilometers (miles) thick. It lies between our planet’s outer crust and its molten outer core.

The edge of one tectonic plate may begin sliding beneath a neighboring one. This process is known as subduction . The downward-moving plate carries rock back toward the mantle, where temperatures and pressures are very high. This disappearing, water-filled rock melts easily.

Because the liquid rock is lighter than the surrounding material, it will try to float back up toward Earth’s surface. When it finds a weak spot, it breaks through. This creates a new volcano.

Many of the world’s active volcanoes reside along an arc. Known as the “Ring of Fire,” this arc surrounds the Pacific Ocean. (In fact, it was the fiery lava erupting from volcanoes all along this boundary that inspired the arc’s nickname.) Along almost all sections of the Ring of Fire, a tectonic plate is shoving beneath its neighbor.

Many more of the world’s volcanoes, especially those located far from the edge of any plate, develop over or near broad plumes of molten material that rise up from Earth’s outer core. These are called “mantle plumes.” They behave very much like the blobs of hot material in a “lava lamp.” (Those blobs rise from the heat source at the bottom of the lamp. When they cool, they fall back towards the bottom.)

Many oceanic islands are volcanoes. The Hawaiian Islands formed over one well-known mantle plume. As the Pacific plate gradually moved northwest over that plume, a series of new volcanoes punched their way through to the surface. This created the island chain. Today, that mantle plume fuels volcanic activity on the island of Hawaii. It’s the youngest island in the chain. 

A small fraction of the world’s volcanoes form where Earth’s crust is being stretched apart, as it is in East Africa. Tanzania’s Mount Kilimanjaro is a prime example. In these thin spots, molten rock can break through to the surface and erupt. The lava they exude can build, layer upon layer, to create tall peaks.

How deadly are volcanoes?

Throughout recorded history, volcanoes have probably killed about 275,000 people, according to a 2001 study led by researchers at the Smithsonian Institution in Washington, D.C. Scientists estimate that almost 80,000 of the deaths — not quite one in every three — were caused by pyroclastic flows . These hot clouds of ash and rock sweep down a volcano’s slopes at hurricane speeds. Volcano-triggered tsunamis likely triggered another 55,000 deaths. These big waves can pose a threat to people living along coasts even hundreds of kilometers (miles) from the volcanic activity.

Many volcano-related deaths happen in the first 24 hours of an eruption. But a surprisingly high fraction — about two in every three — occurs more than a month after an eruption begins. These victims may succumb to indirect effects. Such effects might include famines when crops fail. Or people may return to a danger zone and then die in landslides or during follow-up eruptions.

Each of the past three centuries has seen a doubling of fatal volcanic eruptions. But volcanic activity has remained roughly constant during recent centuries. This suggests, the scientists say, that much of the increase in fatalities is due to population growth or to the decision of people to live (and play) near (or on) volcanoes.

For instance, nearly 50 hikers died on September 27, 2014, while climbing Japan’s Mount Ontake. The volcano unexpectedly erupted . Some 200 other hikers escaped to safety.

How big can a volcanic eruption be?

Some volcanic eruptions amount to small, relatively harmless puffs of steam and ash. At the other extreme are cataclysmic events. These can last for days to months, changing climate across the globe.

Early in the 1980s, researchers invented a scale to describe the strength of a volcanic eruption. This scale, which runs from 0 to 8, is called the Volcanic Explosivity Index (VEI). Each eruption gets a number based on the amount of ash spewed, the height of the ash plume and the power of the eruption.

For each number between 2 and 8, an increase of 1 corresponds to an eruption that’s ten times more powerful. For example, a VEI-2 eruption releases at least 1 million cubic meters (35 million cubic feet) of ash and lava. So a VEI-3 eruption releases at least 10 million cubic meters of material.

Small eruptions pose a threat only to nearby regions. Small clouds of ash might wipe out a few farms and buildings on the slopes of a volcano or on the surrounding plains. They also might smother crops or grazing areas. That could trigger a local famine.

Larger eruptions pose different types of hazards. Their ash can spew dozens of kilometers from the peak. If the volcano is topped with snow or ice, lava flows can melt it. That can create a thick mix of mud, ash, soil and rocks. Called a lahar, this material has a consistency like wet, newly mixed concrete. It can flow far from the peak — and destroy anything in its path.

Nevado del Ruiz is a volcano in the South American nation of Colombia. Its eruption in 1985 created lahars that destroyed 5,000 homes and killed more than 23,000 people. The lahars’ effects were felt in towns up to 50 kilometers (31 miles) from the volcano. 

A volcano’s threats can even extend into the sky. Ash plumes can reach altitudes at which jets fly. If ash (which actually is tiny bits of broken rock) gets sucked into an aircraft’s engine, high temperatures there can re-melt the ash. Those droplets can then solidify when they hit the engine’s turbine blades.

This will disrupt the flow of air around those blades, causing the engines to fail. (That’s not something anyone would like to experience when they are several kilometers in the air!) What’s more, flying into a cloud of ash at cruising speed can effectively sandblast a plane’s front windows to the point that pilots can no longer see through them.

Finally, a really big eruption can affect global climate. In a very explosive eruption, particles of ash can reach altitudes above where rains are available to quickly wash them from the air. Now, these ash bits can spread around the world, diminishing how much sunlight reaches Earth’s surface. This will cool temperatures globally, sometimes for many months.

Besides spewing ash, volcanoes also emit a witches’ brew of noxious gases, including carbon dioxide and sulfur dioxide. When sulfur dioxide reacts with the water vapor spewed by eruptions, it creates droplets of sulfuric acid. And if those droplets make it to high altitude, they too can scatter sunlight back into space, cooling climate even more.

It’s happened.

In 1600, for instance, a little-known volcano in the South American nation of Peru erupted. Its ash plumes cooled global climate so much that many parts of Europe had record-setting snowfalls the next winter. Large portions of Europe also suffered unprecedented floods the next spring (when the snow melted). Heavy rains and cool temperatures during the summer of 1601 ensured massive crop failures in Russia. The famines that followed lasted through 1603.

In the end, this one eruption’s impacts resulted in the deaths of an estimated 2 million people — many of them half a world away. (Scientists didn’t make the connection between the Peruvian eruption and the Russian famines until several years after the 2001 study that estimated the death tolls from all volcanoes in recorded history.)

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

Chapter: summary.

Volcanoes are a key part of the Earth system, and open a window into the inner workings of the planet. More than a dozen volcanoes are usually erupting on Earth at any given time. Some of these eruptions are devastating, killing people, damaging homes and infrastructure, altering landscapes, and even disrupting climate. Fortunately, many eruptions are preceded by signs of unrest (precursors) that can be used to anticipate eruptions and support disaster planning.

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. Eruption behaviors are diverse (e.g., violently explosive or gently effusive, intermittent or sustained, last hours or decades) and may change over time at a volcano. More accurate and societally useful forecasts of eruptions and their hazards are possible by using new observations and models of volcanic processes.

At the request of managers at the National Aeronautics and Space Administration, the National Science Foundation (NSF), 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.

These four tasks are closely related. Improved understanding of volcanic processes guides monitoring efforts and improves forecasts. In turn, improved monitoring provides the insights and constraints to better understand volcanic processes. This report identifies key science questions, research and observation priorities, and approaches for building a volcano science community capable of tackling them. The discussion below first summarizes common themes among these science questions and priorities, and then describes ambitious goals (grand challenges) for making major advances in volcano science.

KEY QUESTIONS AND RESEARCH AND OBSERVATION PRIORITIES

Many fundamental aspects of volcanoes are understood conceptually and often quantitatively. Plate tectonics and mantle convection explain where volcanoes occur. We understand how magma is initially created in Earth’s mantle, how it rises toward the surface, that it can be stored and evolve in magma chambers within the crust, and that a number of processes initiate eruptions. We understand in general terms why some magmas erupt explosively and others do not, and why some volcanoes erupt more often than others. High-resolution observations and models combined provide a detailed and quantitative picture of eruptions once they begin.

Our understanding is incomplete, however, especially those aspects of volcano behavior that define the timing, duration, style, size, and consequences of eruptions. Additional questions relate to our ability to forecast eruptions. What processes produce commonly observed geophysical and geochemical precursors? What factors determine if and when unrest will be followed by eruption? How rapidly do magmas mobilize prior to eruption? Which volcanoes are most likely to erupt in coming years and decades? And we are only beginning to decipher the impacts of large volcanic eruptions on Earth’s climate and biosphere.

Our understanding of the entire life cycle and diversity of volcanoes—from their conception in the mantle to their periods of repose, unrest, and eruption to their eventual demise—is poised for major advances over the next decades. Exciting advances in our ability to observe volcanoes—including satellite measurements of ground deformation and gas emissions, drone observations, advanced seismic monitoring, and real-time, high-speed acquisition of data during eruptions—await broad application to volcanic systems. Parallel advances in analytical capabilities to decipher the history of magmas, and in conceptual, experimental, and numerical models of magmatic and volcanic phenomena, both below and above ground, will provide new insights on the processes that govern the generation and eruption of magma and greatly improve the quality of short-term, months to minutes, forecasts. The time is ripe to test these models with observations from new instrumentation, data collected on fine temporal and spatial scales, and multidisciplinary synthesis.

Four common themes emerged from the research priorities detailed in the following chapters:

• Develop multiscale models that capture critical processes, feedbacks, and thresholds to advance understanding of volcanic processes and the consequences of eruptions on Earth systems.

Advances will come from measurements of physical and chemical properties of magmas and erupted materials, deciphering the history of magmas (before and during eruption) recorded in their crystals and bubbles, and developing new models that account for the numerous interacting processes and vast range of scales, from microscopic ash particles and crystals, to eruption columns that extend to the stratosphere.

• Collect high-resolution measurements at more volcanoes and throughout their life cycle to overcome observational bias.

Few volcanoes have a long record of monitoring data. New and expanded networks of ground, submarine, airborne, and satellite sensors that characterize deformation, gases, and fluids are needed to document volcanic processes during decade-long periods of repose and unrest. High-rate, near-real-time measurements are needed to capture eruptions as they occur, and efficient dissemination of information is needed to formulate a response. Both rapid response and sustained monitoring are required to document the life cycle of volcanoes. Monitoring and understanding volcanic processes go hand-in-hand: Different types of volcanoes have different life cycles and behaviors, and hence merit different monitoring strategies.

• Synthesize a broad range of observations, from the subsurface to space, to interpret unrest and forecast eruption size, style, and duration.

Physics-based models promise to improve forecasts by assimilating monitoring data and observations. Progress in forecasting also requires theoretical and experimental advances in understanding eruption processes, characterization of the thermal and mechanical properties of magmas and their host rocks, and model validation and verification. Critical to eruption forecast-

ing is reproducing with models and documenting with measurements the emergent precursory phenomena in the run-up to eruption.

• Obtain better chronologies and rates of volcanic processes.

Long-term forecasts rely on understanding the geologic record of eruptions preserved in volcanic deposits on land, in marine and lake sediments, and in ice cores. Secondary hazards that are not part of the eruption itself, such as mud flows and floods, need to be better studied, as they can have more devastating consequences than the eruption. Understanding the effects of eruptions on other Earth systems, including climate, the oceans, and landscapes, will take coordinated efforts across disciplines. Progress in long-term forecasts, years to decades, requires open-access databases that document the full life cycle of volcanoes.

GRAND CHALLENGES

The key science questions, research and observation priorities, and new approaches highlighted in this report can be summarized by three overarching grand challenges. These challenges are grand because they are large in scope and would substantially advance the field, and they are challenges because great effort will be needed. Figure S.1 illustrates these challenges using the example of the 2016 eruption of Pavlof volcano, Alaska. The volcanic hazards and eruption history of Pavlof are summarized by Waythomas et al. (2006) .

A principal goal of volcano science is to reduce the adverse impacts of volcanism on humanity, which requires accurate forecasts. Most current eruption forecasts use pattern recognition in monitoring and geologic data. Such approaches have led to notable forecasts in some cases, but their use is limited because volcanoes evolve over time, there is a great diversity of volcano behavior, and we have no experience with many of the potentially most dangerous volcanoes. A major challenge is to develop forecasting models based instead on physical and chemical processes, informed by monitoring. This approach is used in weather forecasting. Addressing this challenge requires an understanding of the basic processes of magma storage and ascent as well as thresholds of eruption initiation. This understanding and new discoveries will emerge from new observations, experimental measurements, and modeling approaches. Models are important because they capture our conceptual and quantitative understanding. Experiments test our understanding. Relating models to observations requires multiple types of complementary data collected over an extended period of time.

Determining the life cycle of volcanoes is key for interpreting precursors and unrest, revealing the processes that govern the initiation and duration of eruptions, and understanding how volcanoes evolve between eruptions. Our understanding is biased by an emphasis over the last few decades of observation with modern instruments, and most of these well-studied eruptions have been small events that may not scale to the largest and most devastating eruptions. Strategic deployment of instruments on volcanoes with different characteristics would help build the requisite knowledge and confidence to make useful forecasts. For every volcano in the United States, a realistic goal is to have at least one seismometer to record the small earthquakes that accompany magma movement. Even in the United States, less than half of potentially active volcanoes have a seismometer, and less than 2 percent have continuous gas measurements. Global and daily satellite images of deformation, and the ability to measure passive CO 2 degassing from space would fill critical observational gaps. Geologic and geophysical studies are required to extend understanding of the life cycle of volcanoes to longer periods of time. On shorter time scales, satellite measurements, emerging technologies such as drones, and expansion of ground-based monitoring networks promise to document processes that remain poorly understood.

The volcano science community needs to be prepared to capitalize on the data and insights gained from eruptions as they happen. This will come from effective integration of the complementary research and monitoring roles by universities, the USGS, and other government agencies. Volcano science is fundamentally interdisciplinary and the necessary expertise is spread across these institutions. The science is also international, because every volcano provides insights on processes that drive eruptions. Volcanic eruptions can have global impacts and so demand international collaboration and cooperation. New vehicles are needed to support interdisciplinary research and training, including community collaboration and education at all levels. Examples of similar successful programs in other fields include NSF’s Cooperative Studies of the Earth’s Deep Interior program for interdisciplinary research and National Earthquake Hazards Reduction

Program for federal government agency–academic partnerships.

Results of the above investments in science will be most evident to the public in improved planning and warning and, ideally, a deeper appreciation of this amazing natural phenomenon.

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

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• 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) ↵

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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.

Tsunami Essay for Kids Essay on Earthquake in English for Children How to Write An Essay On Environmental Pollution for Kids

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70 Volcano Essay Topic Ideas & Examples

🏆 best volcano topic ideas & essay examples, 📌 most interesting volcano topics to write about, 👍 good research topics about volcano, ❓ essay questions about volcanoes.

• The Economic Impact of the Icelandic Volcano Eruptions on the International Economy So, it may be completed that even though the shutdown of the European airspace negatively affected the economics of the whole world and GDP level of the countries, there were the ways for solving the […]
• Eruption of Mount Saint Helen Volcano Helens volcano, looking at its history, the explosion, the immediate consequences of the eruption, and the historic impact on the climate and human life.
• Sparks Fly Over Theory That Volcano Caused Salmon Boom However, for the theory to be credible the volcanic ashes must be rich in iron and spread ashes to oceanic regions that have a limited concentration of iron.
• The Volcano and Aurora in Iceland In other words, the volcano Hekla was erupting from the surface of the earth while the natural light was shining from the sky.
• Haleakalā Volcano and Wai’anapanapa State Park Haleakal is a large shield volcano that is situated in the east of the Island of Maui and basically comprises this part of Maui.
• Review of Related Literature of Volcano Tourism in the Philippines
• The Human Response During a Calamity in A Living God by Lafcadio Hearn and The Volcano Next Door by Michael Finkel
• Investigating the Rate of Lava Flows Down the Side of a Volcano
• The Dangers of Living Too Close to a Volcano
• The Characteristics of Mount Vesuvius, the Only Active Volcano on the European Mainland
• Causes and Effect of Volcano Eruption
• The Most Famous Mount Kilauea Volcano in Hawaii
• The Devastation a Volcano Can Create Shown in In a Volcanoes Path
• What Fundamental Parameters Determine the Vigor or Violence with Which a Volcano Erupts
• The History and Possible Threats of Nyiragongo in The Volcano Next Door, a Book by Michael Finkel
• Volcano Eruptions Types
• Understanding How A Volcano Forms and Erupts
• Volcano: The Eruption and Healing of Mount St. Helens Critical
• The Mount Saint Helens and the Volcano Area in Washington State
• Planet and Live Erupting Volcano
• The Mount St. Helen and Mount Pinatubo Volcano Eruptionss
• The Most Active Volcano Of The Philippines
• An Active Super Volcano Lying Underneath Yellowstone Nation Park
• The Vesuvius Volcano Eruption and the Activities of the Cities Pompeii and Herculaneum
• Why This Volcano Eruption in the Philippines May Be Especially Deadly
• Sitting on a Volcano: Domestic Violence in Indonesia Following Two Volcano Eruptions
• Volcanoes: Volcano and Broad Domed Volcano
• The Lack of Volcano Physics in the Movies
• A Look at the Destructive Power of a Volcano
• An Analysis of the Destructive Power of a Volcano as One of the Most Violent and Deadly of All Natural Forces
• The Importance and Role of Hydrothermal Vents and Underwater Volcano
• Yellowstone: Volcano and Lieutenant Gustavus Doane
• The Devastating Effects of Volcano Eruptions in the U.S
• An Analysis of the Eruption of the Mount St. Helens Volcano on the 18th of May, 1980
• Volcanoes: Volcano and Eruptions Explosive Eruptions
• Volcanoes : The Volcano Of Tambora
• An Analysis of the Question Whether Germany Was Dancing on a Volcano
• The Three Systems to Faults Present in the Nevado del Ruiz Volcano Region
• An Analysis of the Soufriere Hills Volcano Eruption on Montserrat Island in 1997
• Why Can’t Toxic or Nuclear Waste Be Disposed of in Volcanoes?
• What Are the Four Basic Types of Volcanoes?
• What Exactly Are Super Volcanoes?
• Where Do Volcanoes Exist and How They Have Formed?
• Which Is the World’s Largest Volcano?
• What Causes Hotspot Volcanoes?
• What Are the Most Beautiful Volcanoes in the World?
• Which Are the Most Dangerous Volcanoes That Could End the World?
• Why Are Some Volcanoes More Hazardous Than Others?
• Are Volcanoes the Main Cause of Global Warming?
• What Would Be the Side Effects of Dumping Our Trash in Active Volcanoes?
• Is It Possible There Are Active Volcanoes on the Moon?
• Why Are There So Many Volcanoes in the Philippines?
• Is It Possible for Extinct Volcanoes to Ever Become Dormant or Active Again?
• Why Do Most Volcanoes and Earthquakes Occur at Plate Boundaries?
• What Are the Hazards Caused by Volcanoes?
• Why Are Plug Dome Volcanoes Considered Especially?
• What Are Most Dangerous Volcanoes in the US and Why?
• Why Can’t We Harvest Energy From Volcanoes?
• What Is the Most Interesting Thing About the Volcanoes?
• What Islands Have Volcanoes on Them?
• What Are the 3 Main Types of Volcanoes and Their Characteristics?
• Could the Earth Survive Without Volcanoes?
• Which Continent Does Not Have Volcanoes?
• Why Do Volcanoes Erupt on Mountains and Not on Flat Land?
• How Are Underwater Volcanoes Different From Land Volcanoes?
• How Often Do “Extinct” Volcanoes Become Active?
• Where Are the Most Active Volcanoes Located?
• What Is the Distribution of Volcanoes Around the World?
• How Do Volcanoes Influence Climate?
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IvyPanda. (2023, October 26). 70 Volcano Essay Topic Ideas & Examples. https://ivypanda.com/essays/topic/volcano-essay-topics/

"70 Volcano Essay Topic Ideas & Examples." IvyPanda , 26 Oct. 2023, ivypanda.com/essays/topic/volcano-essay-topics/.

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IvyPanda . 2023. "70 Volcano Essay Topic Ideas & Examples." October 26, 2023. https://ivypanda.com/essays/topic/volcano-essay-topics/.

1. IvyPanda . "70 Volcano Essay Topic Ideas & Examples." October 26, 2023. https://ivypanda.com/essays/topic/volcano-essay-topics/.

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IvyPanda . "70 Volcano Essay Topic Ideas & Examples." October 26, 2023. https://ivypanda.com/essays/topic/volcano-essay-topics/.

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To better predict volcanic eruptions, you have to dig deep — very deep

Conditions inside magma chambers may indicate the size, frequency and composition of volcanic eruptions.

In most cases, we know when a volcano is going to erupt. Well, sort of. While we can't predict the precise moment an eruption will begin, volcanoes often show signs that they're "waking up." Typically, those signs come from changes in the volcano itself, as well as from changes within the topmost layers of Earth's crust . But new research, spearheaded by teams from Imperial College London and the University of Bristol, suggests we should be looking deeper — up to 12.5 miles (20 km) underground — at different eruption cues that might help us improve our predictions.

"We looked at volcanoes around the world and dug deeper than previous studies that focused on shallow underground chambers where magma is stored before eruptions," Catherine Booth, a research associate in the Department of Earth Science and Engineering at Imperial College London, said in a statement . "We focused on understanding magma source reservoirs deep beneath our feet, where extreme heat melts solid rocks into magma at depths of around 10 to 20 kilometers."

After collecting data from this part of the Earth 's crust, the team fed that data into computer models. What they found was that certain conditions within deep magma reservoirs could indicate the size, composition and frequency of volcanic eruptions. By studying what's going on below, we can better predict what might happen above.

Related: Volcanoes may carpet surface of newfound Earth-size exoplanet

Magma buoyancy is perhaps one of the more surprising indicators of an eruption. "Contrary to previous beliefs, our study suggests that the buoyancy of the magma, rather than the proportion of solid and molten rock, is what drives eruptions," said Booth. "Once the magma becomes buoyant enough to float, it rises and creates fractures in the overlying solid rock — and it then flows through these fractures very rapidly, causing an eruption."

Another factor is the size of the reservoir itself. While it's true that larger reservoirs hold more magma, that doesn't always mean the eruption will be greater. The larger the reservoir, the more heat is dispersed, reducing the rate of melting rock into magma. Plus, the longer magma sits underground, the smaller the eruption will be.

— Satellites watch Iceland volcano spew gigantic plume of toxic gas across Europe — Tonga volcano eruption was fueled by 2 merging chambers that are still brimming with magma

— Hiding in Plain Sight! Discovery of Giant Mars Volcano  

"By improving our understanding of the processes behind volcanic activity and providing models that shed light on the factors controlling eruptions, our study is a crucial step towards better monitoring and forecasting of these powerful geological events," said Matt Jackson, chair in geological fluid dynamics in the Department of Earth Science and Engineering at Imperial College London.

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‘Buoyant’ magma offers clues about the power of volcanoes

Studying deeper molten rock reservoirs may help scientists better forecast eruptions.

By Laura Baisas | Published May 10, 2024 2:00 PM EDT

Studying the molten rock simmering about 12 miles below the Earth’s surface could help scientists better predict volcanic activity . According to a study published May 10 in the journal Science Advances , these underground reservoirs where rocks are first melted down into liquid magma may help forecast just how explosive an eruption may be. Better predictions of volcanic eruption could potentially save lives and give people more time to get out of danger.

Deeper magma

Predicting when an eruption might occur is still pretty difficult for scientists. Volcanoes do not exhibit the same behavior for long. Many of their eruption histories go back before humans even existed, so it is difficult to follow their eruption intervals . Eruptions are typically predicted based on the activity of the volcano and the upper few miles of the crust beneath it . This layer of crust contains molten rock that is potentially ready to erupt. However, the activity in the deeper magma reservoirs has not been as well studied. 

To learn more about these magma reservoirs further underground, a team from the Imperial College London and the University of Bristol studied the frequency, composition, and size of volcanic eruptions around the world. They reviewed data on 60 of the most explosive volcanic eruptions in nine countries : Argentina, Chile, El Salvador, Indonesia, Japan, New Zealand, Nicaragua, Russia, and the United States.

[Related: A volcanologist shows what makes magma go boom .]

“We looked at volcanoes around the world and dug deeper than previous studies that focused on shallow underground chambers where magma is stored before eruptions,” study co-author and Imperial College London geoscientist Catherine Booth said in a statement . “We focused on understanding magma source reservoirs deep beneath our feet, where extreme heat melts solid rocks into magma at depths of around 10 to 20 kilometers [6.2 to 12.4 miles].”

Scientists combined this global data with advanced computer models to look closer at the composition, structure, and history of rocks deep beneath the Earth’s crust . They compared it with information gathered from active volcanoes to better understand how the magma builds up and behaves deep underground, before rising through the Earth’s crust to volcanoes.

Buoyant magma

Using this data, the researchers created computer simulations that mimic the complex processes of magma flow and storage deep within the Earth. Through these simulations, they gained new insight into a critical piece that may be driving eruptions–buoyancy.

“Contrary to previous beliefs, our study suggests that the buoyancy of the magma, rather than the proportion of solid and molten rock, is what drives eruptions,” said Booth. “Magma buoyancy is controlled by its temperature and chemical composition compared to the surrounding rock–as the magma accumulates its composition changes to make it less dense, making it more ‘buoyant’ and enabling it to rise.”

When the magma becomes buoyant enough to float, it rises up and creates fractures in the solid rock on top. It then furiously flows through these fractures, causing an eruption. 

Magma behavior

In addition to identifying magma buoyancy as an important factor driving volcanic eruptions, the team also looked at how the magma behaves when it reaches more shallow underground chambers just before erupting. According to the team , if the magma is stored here longer, it leads to smaller eruptions. 

[Related: Volcano on island in the Galapagos spews lava into the sea .]

Larger reservoirs may be expected to fuel bigger and more explosive eruptions, but the study found that these large reservoirs disperse more heat. This dispersal slows down the process of melting solid rocks into liquid magma. The team believes that the size of the reservoirs is another key to more accurately predicting how big an eruption will be. 

The study also found that eruptions are rarely isolated. Instead, they are part of a repetitive cycle of activity. The magma released by the volcanoes that they studied was also high in silica . This natural compound is known to play a part in determining how viscous–or sticky–and explosive magma is. High-silica magma tends to be more viscous, resulting in a more intense eruption. 

“By improving our understanding of the processes behind volcanic activity and providing models that shed light on the factors controlling eruptions, our study is a crucial step towards better monitoring and forecasting of these powerful geological events,” study co-author and Imperial College London geologist Matt Jackson said in a statement .

Using magma to make better predictions

According to the team, some of the study’s limitations include that their model focused on how magma flows upwards. The source reservoirs in their model also only had molten rock and crystals. 

“However, there is evidence that other fluids such as water and carbon dioxide are also found in these source reservoirs, and that magma can swirl and flow sideways,” said Jackson.

In future studies, the team would like to refine these models by incorporating three-dimensional magma flow and accounting for different fluid compositions. They hope that this will ultimately allow scientists to predict volcanic eruptions more accurately and better prepare for future natural disasters. 

Laura is a science news writer, covering a wide variety of subjects, but she is particularly fascinated by all things aquatic, paleontology, nanotechnology, and exploring how science influences daily life. Laura is a proud former resident of the New Jersey shore, a competitive swimmer, and a fierce defender of the Oxford comma.

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• Earth Science

A volcano is a landform (usually a mountain) where molten rock erupts through the surface of the planet. There are a huge number of active volcanoes present worldwide. In this article, we will learn about the definition, formation and types of volcanoes.

What Are Volcanoes?

A volcano is a landform, a mountain, where molten rocks erupt through the surface of the planet. The volcano mountain opens downwards to a pool of molten rocks underneath the surface of the earth.

Pressure builds up in the earth’s crust and this is the reason why eruptions occur. Gases and igneous rocks shoot up and splash over or fill the air with lava fragments. The volcano eruption can cause hot ash, lateral blasts and lava flow, mudslides, and more.

Formation of Volcanoes

A volcano mountain is formed by the surface eruption of magma from within the earth’s upper mantle. The magma that erupts to the surface and forms a lava flow that deposits ash. As the volcano continues to erupt, a new layer of lava is added to the surface, accumulating to form a mountain.

Different Stages of Volcanoes

They tend to be conical although there are a variety of forms, depending upon:

• The nature of the material erupted
• The type of eruption
• The amount of change since the eruption

Volcanoes are categorised into three main categories:

• Active Volcanoes: A volcano will be classified as an active volcano if at the present time it is expected to erupt or is erupting already.
• Dormant Volcanoes: The classification of volcanoes which is called dormant would be a volcano that is not erupting or predicted to erupt in the near future.
• Extinct Volcanoes: An extinct volcano is a volcano that no one expects will ever have another eruption.

Reason Behind the Eruption of Volcanoes

The volcano eruption begins with the formation of magma in the lower section of the earth’s crust. The earth’s crust is made up of massive slabs called plates, which fit together like a jigsaw puzzle. The friction during the movement of plates causes earthquakes and volcanic eruptions.

With pressure, it travels upwards with tremendous force hitting solid rocks and other materials and creates a new passage to the earth’s surface. Once the magma reaches the air it is called lava.

Types of Volcanoes

These are grouped into four types:

• Cinder cones
• Composite volcanoes
• Shield volcanoes
• Lava volcanoes

Cinder Cones: These are the simplest type of volcano. They occur when particles and blobs of lava are ejected from a volcanic vent. The lava is blown violently into the air, and the pieces rain down around the vent. Over time, this builds up a circular or oval-shaped cone, with a bowl-shaped crater at the top. Cinder cone volcanoes rarely grow larger than about 1,000 feet above their surroundings.

Composite Volcanoes: Composite volcanoes are some of the Earth’s grandest mountains, and they are also called stratovolcanoes. They are typically symmetrical cones of large dimension built of alternating layers of lava flows, steep-sided, volcanic ash, blocks, bombs, and cinders and may rise as much as 8,000 feet above their bases.

Shield Volcanoes: A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They have very gentle slopes and are developed horizontally. Shield volcanoes are built by effusive eruptions, which flow out in all directions. They almost never have violent eruptions, with basic lava simply flowing out.

Lava Domes: Lava domes are the fourth type of volcano that we are going to discuss. Unlike composite and shield volcanoes, lava domes are of tiny stature. They are formed when the lava is too viscous to flow to a great distance. As the lava dome slowly grows, the outer surface cools and hardens as the lava continues to pile within. Eventually, the internal pressure can shatter the outer surface, causing loose fragments to spill down its sides. Generally, such lava domes are found on the flanks of larger composite volcanoes.

The video about the eruption of volcanoes

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The Unusual Evolutionary Journey of the Baobab Tree

New research shows the “upside-down trees” originated in Madagascar and then caught a ride on ocean currents to reach mainland Africa and Australia.

By Rachel Nuwer

Baobabs are one of the most charismatic trees on Earth, thanks in part to their unusual appearance. Their cartoonishly thick trunks are conspicuously oversized relative to their diminutive crowns, earning them the nickname “upside-down trees.” They can also live for thousands of years , contributing to their prominent place in cultural traditions and works of art.

For all the tales told about baobabs, though, their origin story has remained a mystery.

Scientists have debated for years how baobabs wound up in the places where they grow. Eight species exist around the world, and their distribution, like the trees themselves, is unusual: One species occurs across much of mainland Africa, while six are in Madagascar. The last is found faraway, in northwestern Australia.

Most researchers have hypothesized that the trees originated on mainland Africa. But findings published Wednesday in the journal Nature tell a different story. Baobabs instead most likely first evolved in Madagascar , where they diversified into different species. Two then embarked on long-distance oceanic journeys to distant continents.

“Madagascar is this wonderful natural laboratory,” said Tao Wan, a botanist at the Wuhan Botanical Garden of the Chinese Academy of Sciences and an author of the new study. He added, “In the case of baobabs, some very special geographical history on the island contributed to the species’ diversity.”

Dr. Wan and his colleagues sequenced the genomes of all eight baobab species and then used those data to understand how the trees evolved. They also investigated ecological factors that influenced the distribution of baobabs around Madagascar.

Their results indicate that baobabs’ common ancestor most likely arose in Madagascar around 21 million years ago. Competition with other plant life and factors like altitude, temperature, precipitation and volcanic activity caused new baobab species to emerge across Madagascar, as did fluctuating sea levels during various ice ages.

Baobabs probably also evolved a mutualistic relationship with lemurs that served as pollinators. Other relatively large animals, including fruit-eating bats and bush babies in Africa, began visiting baobabs’ nocturnal flowers for nectar. “One of the evolutionary innovations of baobabs was to exploit large, sugar-eating animals,” said Andrew Leitch, a plant geneticist at Queen Mary University of London, and an author of the study. “That’s an unusual thing for a plant to do.”

At some point, most likely around 12 million years ago, two species of Malagasy baobabs found their way to mainland Africa and Australia, where they evolved into the unique trees that grow there today. Most likely, multiple baobab seeds hitched rides as vegetation was transported by the Indian Ocean gyre, a current that circulates counterclockwise between Australia, South Asia and the eastern coast of Africa — exemplifying the species’ “fascinating and extraordinary long-distance dispersal patterns,” Dr. Leitch said.

“Baobabs are amazing trees, so I was excited to see this paper,” said Pamela Soltis, a botanist at the University of Florida who was not involved in the work. She added that the research offered new perspectives on baobab evolution.

In addition to filling in missing pieces of the evolutionary puzzle, the authors’ findings also raise conservation concerns. Two of the Malagasy species have alarmingly low genetic diversity, indicating that they might lack the resilience needed to adapt to climate change. A third species is also at risk of disappearing because of interbreeding with a more widespread cousin.

These three species are already listed on the International Union for Conservation of Nature’s Red List as being in danger of extinction. The new genetic findings suggest that their conservation statuses should be re-evaluated and potentially upgraded to even higher threat levels, said Ilia Leitch, a plant geneticist at the Royal Botanic Gardens in Kew and an author of the paper.

All six of the Malagasy baobab species are also being affected by an ongoing wave of extinctions that has been occurring in Madagascar for the past 2,500 years and that researchers say is mostly being driven by human activity. Several species of giant lemurs — some of which grew to gorilla-size proportions, and all of which probably served as key seed dispersers for baobabs — were hunted to extinction around 1,000 years ago. Virtually all of the forested understory that surrounded Madagascar’s baobabs has also been lost to recent development.

While species naturally come and go across evolutionary history, “that process is being exacerbated by human intervention,” Dr. Ilia Leitch said.