SUPERVOLCANES

Supervolcanoes represent the strongest and most dangerous volcanoes on Earth. They are considered to represent the greatest natural force, a greater force than which exists today only in space. There are about 40 of them, most of which have been shut down. They rarely work and then they can lead to a big disaster. They are able to change the appearance of the entire continent, to change the global climate of the planet and drastically reduce the number of living beings on Earth.
The term supervolcano itself means a volcanic eruption with a magnitude of 8 on the Volcanic Explosivity Index. The volcanic explosivity index is an 8-point scale from 1 to 8 that indicates how much lava and ash is ejected during an eruption. For example, the eruption of the Saint Helena volcano in 1980 threw out 2 cubic kilometers of lava and ash, and it had a strength of 1 on the IEV. A supervolcano eruption would eject more than 1,000 cubic kilometers of material.
The main difference between supervolcanoes and ordinary volcanoes is that in supervolcanoes the magma is located in large chambers located only a few kilometers below the surface. The chamber is slowly and steadily replenished, while the pressure also increases. Due to the increase in pressure, the ground rises. When the pressure becomes strong enough, an eruption occurs. The eruption of a supervolcano does not result in the formation of a conical mountain, but a huge circular caldera. These volcanoes actually collapse into the space from which the magma and ash that is enough to cover tens of thousands of square kilometers of the surface with thick deposits first erupts. The eruption also ejects a large amount of sulfur and ash, which is so abundant that it could cause a nuclear winter. In picture no. 1 you can see the locations of some of the supervolcanoes. Today's most famous supervolcanoes are Yellowstone and Toba.

Yellowstone

Beneath the world's oldest national park, Yellowstone, lies the world's largest supervolcano. It was discovered in the sixties of the twentieth century by recording infrared spectrum rays from satellites.
The park itself covers an area of ​​nine thousand square kilometers. It is located on the border of three federal states: Montana, Idaho and Wyoming (picture no. 2). The park is a concentration of the most diverse forms that nature has come up with. It has lakes, canyons, rivers and mountain ranges. It is home to 300 geysers and half of all the world's over ten thousand geothermal sources. A variety of wild animal and plant life thrives in it.

Yellowstone Park



However, all those phenomena such as geysers and warm lakes, fumaroles, etc. indicate that something is happening under the park.

Tank
Beneath the park is a hot spot 2,900 kilometers long that slowly feeds magma into the layers below the Earth's crust. In places under the surface where magma collects, a magma reservoir is formed (picture no. 3). The magma reservoir is roughly 40 km to 80 km in diameter and a similar size to the caldera that sits above it. The top of the reservoir is about eight kilometers below the surface, while the bottom is some 16 kilometers away. However, the reservoir is not only filled with fluid magma. The magma is partially molten, which means that only part of the rock is melted (about 10 to 30 percent). The rest of the material is solid, but therefore very hot.
To get the size of the chamber, scientists use a method similar to X-ray scanning of the human body in medicine, where when X-rays are passed through the body, a 3-D image of the internal organs is obtained. In an analogous way, a method called seismic topography, using thousands of seismograms that measure the speed of seismic waves from earthquakes and small tremors caused by dynamite, provides data that makes it possible to create a 3-D image of the Earth's interior. In this way, the size of the tank can be determined.

There are two types of magma in the reservoir - acidic and basic.

The basic fog comes from the interior of the earth, while the acidic fog is created by the melting of the existing rock. Due to the constant inflow of magma, the reservoir is constantly increasing, due to which there is an increase in pressure. The increase in pressure is manifested by the fact that magma moving upwards when it reaches the top of the chamber begins to crystallize and become denser, releasing gases that increase the pressure. Due to the increase in pressure on the surface of the crust, a bulge appears. When the pressure becomes critical, the Earth's crust cracks, releasing a large amount of magma, gas, and ash. When the pressure is released the Earth's crust which was bulging now falls into the emptied chamber where the magma used to be, forming a large depression called a caldera.


The past

Scientists claim that the hot spot under Yellowstone has existed for 17 million years. However, the hot spot has not always been under Yellowstone.

The hot spot was created on the border of three federal states: Oregon, Nevada and Idaho. Due to the movement of the North American Plateau to the southwest, there is also a movement of the place where the magma is deposited. In this way, the hot spot moved north-east, during which it erupted many times. This is evidenced today by several ancient calderas, most of which are part of the plains around the Snake River. The hot spot reached beneath Yellowstone about 4 million years ago.

The Yellowstone area has produced 3 extremely powerful volcanic eruptions in the past 2.1 million years. In each of these cataclysmic events, huge amounts of magma erupted to the surface and into the atmosphere as a mixture of hot lava, volcanic ash (small sharp fragments of volcanic glass and lava), and gases that spread in all directions in pyroclastic flows.

The first of these caldera-forming eruptions created a large volcanic deposit known as the Huckleberry Tuff 2.1 million years ago. This massive event formed a caldera more than 100 kilometers in diameter. On this occasion, he ejected 2,450 cubic kilometers of volcanic material.
A similar, but smaller, yet huge eruption occurred 1.3 million years ago. This formed the Henritz Fork caldera in the Island Park area, west of Yellowstone National Park and also a volcanic deposit called the Mesa Falls tuff.

The most recent similar eruption of 640 thousand years ago created the Yellowstone caldera, which is 55 km wide and 80 km long. The pyroclastic flow of this eruption left behind thick deposits of volcanic sediment known as the Lava Creek Tuff. They form the northern wall of the caldera (picture no. 4). Huge amounts of volcanic ash were thrown into the atmosphere and deposits of this ash can be found in places in Iowa, Louisiana, California that are quite far from Yellowstone.
Minor eruptions occur every 20 thousand years, while small ones occur almost daily. If we look at the periods of large eruptions, we will see that they occur every 600 to 700 thousand years, so the last eruption is already late.


A disaster

The next Yellowstone eruption is expected to be 2,500 times more powerful than the 1980 St. Helena eruption that spewed so much magma that London could be covered in 4 meters of ash. A Yellowstone eruption could cover the whole of Britain with 4 meter ash deposits. The eruption of this volcano would release every second the energy of 1000 atomic bombs dropped on Hiroshima. The sound that would be heard on that occasion would be the loudest that the human species has ever heard since living on the planet, which is about 75,000 years.

The magma that would have erupted on that occasion would have thrown over 2,000 million tons of sulfuric acid 50 kilometers high into the stratosphere. Lava 30 meters thick would have covered the 103 square kilometer region around the eruption. The national park would be completely gone and the surrounding towns would be destroyed by lava, pyroclastic flow and ash. Ash deposits around the volcano would be 6 meters and at a distance of about 400 kilometers with half a meter thick deposits.
The long-term effects of the cataclysm would be even worse. Due to a thousand cubic kilometers of ash in the atmosphere, the passage of the sun's rays would be blocked, photosynthesis in plants would be disabled and the global temperature would drop sharply to a maximum of 12 degrees in the northern hemisphere and to 1 degree in the southern. A so-called nuclear winter would occur. At least one billion people would die.

Hydrothermal explosions

Yellowstone's large magma reservoir reaches temperatures of more than 800 degrees Celsius, heating the rocks surrounding it. Because of this, the average heat flow at the earth's surface is about 30 times greater than anywhere else in the Rocky Mountains. As snow and rain settle into the ground, they absorb enough of this energy to heat surface waters almost to boiling point. The geysers and other thermal areas of Yellowstone National Park are places where that water from the ground makes its way to the surface. Drilling of the ground for research during the 60s confirmed that the water below the surface is very hot. In the Norris Basin at a depth of only 332 meters, temperatures of 238 degrees Celsius were recorded.

Because the boiling point of water increases with pressure, and pressure with depth, groundwater can be hotter than boiling water closer to the surface. If the pressure is reduced quickly, the water pockets can boil over, causing an explosion when the water turns to steam. Such processes lead to geyser eruptions, such as Old Faithful, which spews out steam and water at regular intervals; less often, explosions are stronger and water is ejected from the rock more than 300 meters into the air. In Yellowstone's geologic past, such sudden events, called hydrothermal explosions, occurred countless times, creating new hills and craters. A more significant hydrothermal explosion occurred in 1989 at Porkchop Geyser in the Norris Basin. The remains of this explosion are still clearly visible today as a ring of rock fragments 5 meters above the central source of Porkchop. 1889 and early 1890. a series of explosions and geyser eruptions occurred at Excelsior Geyser in the Midway Basin. Some of the explosions threw rocks up to 15 meters away. Much more powerful hydrothermal explosions have occurred in Yellowstone during its geologic past.

More than a dozen large craters formed by hydrothermal explosions in the period from 14,000 to 3,000 years ago were caused by sudden changes in the pressure of the hydrothermal system. Many of these craters are within the Yellowstone caldera or along the north-south line between the Mammoth and Norris basins. The largest crater created by a hydrothermal explosion in the world. It is located along the northern edge of Yellowstone Lake in Mary Bay.

This crater is 2.6 km long. it was formed about 13,800 years ago and may have been created by means of several consecutive explosions in short time intervals. What exactly triggered these large events is not clearly established, but significant factors were probably sudden changes in lake level or earthquakes and pressure changes due to melting glaciers. These large and dangerous hydrothermal explosions are unrelated to volcanic activity. Not one of them in the past 16,000 years was accompanied by a magma eruption. Deeper magma systems are not associated with spectacular steam explosions and crater formations. And if powerful hydrothermal explosions are part of Yellowstone's recent geologic history, most of them have historically been relatively weak and left craters only a few meters in diameter. For example, in early 2003, a long fissure appeared on the hill above Nimt Lake, north of Norris Basin, emitting steam and pieces of rock. And if most of the hydrothermal explosions in the park are weak, their remains can be seen. They testify to the careful observer of the continuous geological activity of Yellowstone
In August 2003, geologist Liz Morgan published the results of her four-year research, where she discovered that there was a 610-meter-long swelling of the ground at the bottom of Yellowstone Lake. The elevation is about 30 meters high, like a ten-story building, and is the result of enormous pressure from below. Whether it is the pressure of water or magma, no one knows yet. If it is magma, the mentioned disaster is coming. If it is water, it can cause a powerful hydrothermal explosion Small hydrothermal explosions occur every few years in the geyser basin. Large hydrothermal explosions occur at intervals of several thousand years, and they leave huge craters.

Released energy


One square meter of the earth at this place emits heat equal to 2 W. If the heat is released over 50 square meters and converted into electricity, a 100 W light bulb could be lit. The whole of Yellowstone releases 5 GW of energy, which would be converted into electricity , was enough for a city of two million people. Today, Yellowstone's soil emits 30 to 40 times more heat than the average North American.


Earthquakes


Between 1,000 and 3,000 earthquakes occur within Yellowstone and its immediate surroundings each year. Although too weak to be felt, these earthquakes maintain the active nature of the Yellowstone region, one of the most seismically active in the US. Every year people feel earthquakes of magnitude 3-4.

Although some earthquakes are caused by rising magma and the interaction of water and hot soil, many are also caused by folding of the earth's crust, when mountains are formed. For example, the major folds along the Tetons, Madison, and Galatsia Plateaus run through the national park and probably existed long before any volcanic activity. The triggering of these folds can cause powerful earthquakes. The biggest earthquake in recent history
Yellowstone occurred in 1959, centered near Hebgen Lake, west of the national park. It had a magnitude of 7.5, causing great material damage and killing 28 people, most of them in the landslide it caused.

Geologists conclude that large earthquakes like the one at Hebgen Lake are unlikely in the Yellowstone caldera area because surface temperatures are high, which softens the rocks and makes them less likely to break. However, earthquakes inside the caldera can have a magnitude of up to 6.5. An earthquake of approximately this strength that occurred in 1975. near the Norris Geyser Basin, were felt in the region.

Even distant earthquakes can affect Yellowstone. In November 2002, a magnitude 7.9 earthquake struck the Denali Fault in Alaska, some 3,100 km from Yellowstone. Since the energy of this earthquake was directed towards the active Jeluostuonian volcanic and hydrothermal system, it caused several smaller earthquakes there. The hydrothermal system of the region is very sensitive to earthquakes, and undergoes significant changes during them. Earthquakes may have the potential to destabilize the Yellowstone Warm Water System and cause explosive hydrotreme eruptions.



Eruption yes or no?


One of the most famous English eschatologists (Doomsday scholar), Jan Gurney, warns that an eruption will soon occur on Yellowstone. Some scientific indications and doubts lead him to this. Namely, on July 22, 2003, the Yellowstone Park administration announced that due to the increase in hydrothermal activity around the Norris Geyser Pool, visitors will not be temporarily allowed access. By the way, one of the biggest attractions in the park is the geyser called "Steamer" (picture no. 6). It is known that a geyser is formed when water flows through cracks in rocks of volcanic origin to hot magma. Water heated in this way creates steam, which under pressure tries to find its way through openings and cracks in the rocks. The more steam that appears, it means its continuous release from the magma space.


As the steam escapes, the pressure and amount of water on the magma decreases. When the super hot water in the magma accumulates and the pressure drops, it explodes, erupting on the surface as a geyser and up to 100 meters high. Unfortunately, when the steam does not come out of the cracks, and its quantity decreases, a false image of rest is created. It can only be a lull before an even stronger storm. The "steamer" will be, according to scientists' calculations, very active in this century. Between 1991 and 2000, there were no eruptions. However, since May 2000, "Parobrod" has been activated 5 times. The last time, on April 27, 2003. However, on the other hand, scientists claim that the eruption will not occur for the next thousand or maybe 10 thousand years. They believe that there will be warning signs a decade or a century in advance indicating that an eruption is about to occur. Those signs should be in the form of many earthquakes, massive bulges of the earth, swarms of earthquakes in specific places, changes in the chemical composition of the lava during small eruptions, changes in the composition of the gases produced during evaporation, and also a large degree of fracturing of the Earth's crust.

None of these signs are present yet.

However, it is most important for scientists to understand the mechanism of activation of this volcano, in order to know if a period of instability has come. It is only certain that there will be eruptions, because the accumulated magma must be released.