How did volcanoes form? Volcano is a very dangerous existence. In the history of the earth, volcanic eruptions have occurred countless times. Volcanoes are mainly distributed along the Pacific coast, so Indonesia has the most volcanoes in the world. Share a video of how volcanoes form.

How did volcanoes form? Video 1 Formation of Volcano

According to the theory of plate tectonics, the movement of plates is caused by thermal convection in the asthenosphere inside the earth. When plates push each other, one side with higher density will fall below the other side, which is called subduction, and the belt area where subduction occurs is called subduction zone or convergent plate boundary. The high temperature underground will melt the hidden plates and form magma. Magma rises slowly by buoyancy, and finally converges into a magma chamber, and magma chamber is the place where magma is stored at the bottom of the volcano.

When the gas pressure in the magma accumulates to a certain extent, the volcano erupts. For example, most volcanoes in the Pacific Rim are of this type. Some volcanoes are distributed at the boundary between plates, that is, the belt-shaped area where the two plates are separated. In this area, high-temperature mantle material will rise and form submarine volcanic mountains, which are called mid-ocean ridges.

The movement of hot spots forms a chain of volcanic islands, and some volcanoes are not located at the junction of plates, such as the Yellowstone composite crater in the United States and the Hawaiian Islands. Volcanologists call these volcanoes "hot spots".

At present, the mechanism of hot spots is not clear, but scientists generally believe that hot spots are caused by "hot columns" rising at the bottom of the mantle. When the plate moves horizontally on a hot spot, a series of volcanoes will be produced. After this continuous action, a series of volcanic islands will be formed, and the farther away from the hot spot, the older the volcano is.

Volcanic eruption process

The formation of volcanoes involves a series of physical and chemical processes. At a certain temperature and pressure, the rocks in the crust and upper mantle are partially melted and separated from the parent rocks, and the molten body moves upward through pores or cracks, and gradually enriches in some parts, forming magma sacs. With the continuous supply of magma, the excess pressure of magma in the magma sac gradually increases. When the strength of the crust cover is not enough to stop the magma from moving upward, the magma rises to the surface through the weak zone.

In the process of rising, the volatiles dissolved in magma gradually dissolve out and form bubbles. When the volume fraction of bubbles exceeds 75%, the bubbles trapped in the liquid will be released quickly, leading to explosive eruption. After the gas is released, the viscosity of magma drops to a very low level and the flow becomes turbulent. If the viscosity of magma is low or volatile matter is less, it will only overflow quietly. The difference of a series of physical and chemical processes from partial melting to eruption has formed various volcanic activities.

The process of volcanic eruption

The process before the volcano erupts from the surface can be summarized into three stages: magma formation and initial rising stage, magma sac stage and magma sac leaving the surface stage.

1, magma formation and initial rising stage

Magma must have two processes: partial melting and separation of molten body from parent rock. In fact, these two processes cannot be independent of each other, and the separation of molten body and parent rock may have occurred at the beginning of melting. Partial melting is the * * * existing state of liquid (magma) and solid (crystal), which is produced with the increase of temperature, the decrease of pressure and the decrease of solidus. When some molten substances rise with the mantle flow, liquid-solid separation will also occur in the flow, which will lead to the movement and even aggregation of liquid, which is called melting away.

2. Magmatic capsule stage

Magma sac is an area filled with magma below volcano, and it is a place where magma is relatively enriched in the rock medium of crust or upper mantle. It is generally considered to be a high-temperature fluid in rock pores (or fractures) similar to oil reservoirs, and it is generally considered that magma only accounts for 5%-30% of the total volume in the mantle plume. A part can be considered as a collection of liquids with relative circulation inside. Magma is a mixture of molten magma, volatiles and crystals.

3. From magma sac to surface stage

The rise of magma from the magma source to the near surface is related to the overpressure of magma sac, the formation and penetration of channels, the crystallization and degassing process of magma rise. When the tensile stress or shear stress in the crust is greater than the local rock fracture strength, it may form tensile stress or shear stress cracks. If these faults are interconnected, they can be used as channels for magma eruption.

Volcanic eruption conditions

Whether a volcano can form in a place mainly depends on whether the following conditions are met:

1, the formation of partial melting must have high geothermal energy (self-accumulation or external boundary conditions), or uplift and decompression process, or dehydration to lower the solidus;

2. The enrichment of magma in the earth's crust, or the location where magma sacs are formed, is related to the depth of neutral buoyancy surface, which in turn is related to the rheological discontinuity of the earth's crust;

3. Physical and chemical processes in magma chamber are mainly fractionation and interaction of crystals, volatiles and fluids, and magmatic eruption plays a role in promoting or inhibiting. The existence of magma sac in the crust has played a role in intercepting and transforming the magma rising from the mantle. It is also an important condition for the formation of explosive volcanic eruption.

4. The existence of magma sac can promote the formation of magma channel, and the tensile stress field produced by tectonic activity is the main reason for the formation of magma channel.

5. The rise of magma after leaving the magma sac is driven by pressure gradient and buoyancy.

How did volcanoes form? Video 2 The most beautiful volcano in the world.

Greek island of santorini

The most famous Greek island, santorini, is its pure white building under a colorful cliff. According to historical records, about 1600 BC, after a huge volcanic eruption, the whole island and the indigenous tribes on the island were wiped out, leaving behind a volcanic mortar that is now santorini Island.

Today, it attracts tourists from all over the world to visit the remains of volcanic eruption. "Only when you come in by boat and stand on the cliff to enjoy the sunset in the Aegean Sea can you feel its magnificence." Archillas Walther Lars said.

Especially worth seeing is the New Kameni Island, which is located in the center of santorini volcanic mortar. "New Kameni Island is located in the center of the magnificent volcanic mortar. As far as it is concerned, it is not beautiful, just a dark brown island, "said Smith Prasad. "But there are some different landscapes on the island. Ancient and modern volcanic eruptions have formed potholes with slopes here-it is not the same as the' crater in the traditional sense'. "

Mayon volcano, Philippines

Mayon volcano, located 450 kilometers southeast of Manila in Luzon Island, is the most active volcano in the Philippines. The volcanic eruption in September 20 14 forced thousands of residents to flee the area. Mayon volcano belongs to layered volcano. The steep volcanic cone formed by multi-layer magma is famous for its symmetry.

"The perfect hyperbolic shape of Mayon volcano in the Philippines enhances its aggressive momentum," Vortselas said. "Volcanic ash flow and lava flow also increase the attraction of the volcano."

Hikers can overlook Albay Province and the Pacific Ocean. Here, visitors can also visit the ruins of Kaguzaba Church. It used to be a Franciscan church in 18th century, but it was destroyed in the volcanic eruption in 18 14. This stone pagoda has been preserved to this day. This building is opposite to the natural wonders in the distance.

Mount Kilimanjaro and Mount Ngorongoro in Tanzania

Explorers from all over the world will travel to the border between Tanzania and Kenya to challenge Kilimanjaro, the highest mountain in Africa. But not everyone knows that this mountain is also the highest volcano in Africa. It is special in that it has three volcanic cones. Mount Marvin and Mount Sheila are dormant, but the highest Kibo volcano is still active.

Explorers who are eager to climb the 5898-meter peak in Uhuru must be prepared to experience a sharp change in temperature. Julien Vache said: "During climbing, you will experience a temperature change from 35 degrees to minus 15 degrees."

Ngorongoro volcano is located about 200 kilometers west of Mount Kilimanjaro. It used to be a volcano and was thought to be close to the height of Kilimanjaro. It was estimated to be 4,500 to 4,800 meters high before the collapse. Today, Ngorongoro crater is 22.5 kilometers in diameter and 665,438+00 meters in depth, making it the largest crater in the world. It creates a living environment for local wildlife.

The waterfall above the crater watered the green land and formed a lake at the bottom of the crater. A large number of animals live on the shore: flamingos, lions, hippos, buffaloes, zebras, wildebeests and rhinos. Vacci said.

Cremutu volcano, Indonesia

The three volcanic lakes in Krimutu attract people to Flores Island in East Nusa Tenggara province, Indonesia. "One lake is emerald green, one is crimson, and the other is dark black," Vachi explained. Scientists say that the color of the lake is formed by the chemical reaction between volcanic gas and minerals in the lake.

However, nearby residents hold different views. "The locals believe that the lake is the resting place of the soul, because different souls will show different colors." Sunni Mewati said. "Although science has explained the causes of different colors, people still think that there are souls in the lake."

Kilauea volcano and Monaque volcano.

Kilauea volcano is the youngest volcano in Hawaii. It has been erupting continuously since 1983. "The eruption was very violent, and the magma fell into the sea, forming a grotesque black rock." Vacci said.

Contrary to Kilauea volcano, Monaque sub-volcano has a history of about/kloc-0.0 million years. Although it is dormant, the scale of the peak at an altitude of 4205 meters is still amazing. "The Monaque volcano in Hawaii is beautiful and full of mysterious treasures. There is a frozen lake on the top of the mountain. The only way to get there is to walk. " Leslie Simmons said.

Mount fuji, Japan

Mount Fuji in Japan is probably the most famous volcano in the world. It has been the source of inspiration for many artistic creations for thousands of years. "It's a symbol of Japan: it's snowy in the distance and cherry blossoms are in full bloom." Vacci said. Besides Mount Fuji, Jyukai, located in the northwest of Mount Fuji, is also very famous. It is the most famous "suicide forest" in Japan, accompanied by many supernatural legends.

There are rich magnetite in the ground here, which makes the compass fail and may also make people get lost and die. But Mount Fuji itself is a safe haven-Mount Fuji has not erupted since 1707, and it is a low-risk active volcano.

How did volcanoes form? Video 3 10 deadly volcano in the world

No.65438 +0 Yellowstone National Park Super Volcano

Location: Wyoming, USA

Outbreak time: 640,000 years ago

Volcanic explosivity index: Grade 8.

Lava volume: 2450+ cubic kilometers

Power: About 800,000 Hiroshima atomic bombs.

In the past 265,438+million years, there have been three volcanic eruptions with an explosion index of 8 in Huangshi National Park, the most recent one happened 640,000 years ago.

According to the US Geological Survey, the volcanic ash and magma ejected by the three big explosions in Yellowstone National Park are enough to fill the entire Colorado Grand Canyon. But this is not the most terrible. In recent years, scientists have detected a huge magma mass underground in Yellowstone National Park. How big is this magma mass? Once it erupts, it can fill 1 1 Colorado Grand Canyon.

For Yellowstone volcano, NASA once put forward a proposal, that is, drill a hole in Yellowstone volcano and use the principle of high-pressure water pump to release part of geothermal energy and use this part as new energy. This sounds like a lot of benefits, no harm. But in fact, the operation is very complicated. A little carelessness will not only release geothermal energy, but also accelerate the volcanic eruption, so scientists have no suitable method to stop the possible eruption of this volcano.

But don't worry too much, because scientific research shows that the possibility of Yellowstone volcano eruption is about one in 730 thousand.

Taubo No.2 volcano

Venue: North Island, New Zealand

Outbreak time: 26,500 years ago

Volcanic explosivity index: Grade 8.

Lava volume: 1200-2000 cubic kilometers.

Power: About 500,000 Hiroshima atomic bombs.

Taupo Volcano Area is a volcanic area in the North Island of New Zealand, named after lake taupo, and lake taupo is the largest crater lake in this area. The Taupo volcano area has been active for the past 2 million years and is still very active.

Tao Bo volcanic eruption is the latest super volcanic eruption in the world. It happened about 26,500 years ago, and volcanic explosivity index was 8000km long, spewing out substances of 1 170km. The debris generated by the volcanic eruption covered most of the central part of the North Island, and it was fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused, fused.

No.3 Tambora volcano

Venue: Sombawa Island, Indonesia

Outbreak time: 18 15 years.

Volcanic explosivity index: Level 7.

Lava volume: 150 cubic kilometers

Power: About 50,000 Hiroshima atomic bombs.

1865438+On April 5, 2005, the lava of Tambora volcano, which had been sleeping for 5,000 years on Sombawa Island, Indonesia, erupted with great momentum. Five days later, at about 7 pm on April 18 15, the Tambora volcano erupted again, and it continued intermittently for more than 100 days.

According to historical data, this is the largest eruption of Tambora volcano in two centuries, and it is also the most serious volcanic disaster ever recorded in history. The energy released is equivalent to 50,000 times the explosive power of the atomic bomb dropped by the United States in Hiroshima, Japan at the end of World War II, resulting in117,000 people killed. The eruption of Tambora volcano is ten times as violent as that of Krakato volcano in 1883.

Due to the eruption of Mount Tambora, there was no summer in 18 16, because 240 cubic kilometers of dust produced by volcanic eruption spread all over the atmosphere, which led to great changes in weather patterns around the world in recent months.

In the United States, a year without summer brought food shortage, religious revival and great migration from New England to the Midwest.

In Europe, a year without summer has brought about agricultural failure, widespread famine, riots of hungry people, floods in many major rivers and the worst epidemic typhus in history. In addition, unusual colors, huge sunspots and other strange phenomena in the sky.

No.4 Henna Pedina volcano

Location: Peru

Outbreak time: 1600 years

Volcanic explosivity index: Grade 6.

Lava volume: 30 cubic kilometers

Power: about 10000 Hiroshima atomic bombs.

Mount Etna 10922 feet above sea level. It is one of the most active volcanoes in Europe and has become one of the beautiful landscapes of Sicily, the largest island in the Mediterranean. Scientists believe that Mount Etna is the oldest active volcano on the earth, which erupted many times nearly ten years ago.

However, the Dina volcano eruption in Hennape in 1600 is the largest volcanic eruption in South America. The eruption sent debris into the Pacific Ocean 120 km away, destroying several kilometers of surrounding villages. What's more, the volcano spewed huge smoke and ash into the atmosphere, which seems to have a serious impact on the global climate. In the coming year, the global temperature will drop by an average of 0.5 degrees Celsius, and that summer in Peru will be the coldest in more than 500 years.

No.5 Karakato volcano

Venue: Krakato Island, Indonesia

Outbreak time: 1863

Volcanic explosivity index: Grade 6.

Lava volume: 2 1 cubic kilometer

Power: About 80 million Hiroshima atomic bombs.

Krakatoa volcano on Krakatoa Island in Indonesia is one of the most terrible volcanoes in the world. 1883 made a loud noise a few weeks before Krakatoa erupted, and finally erupted on April 26th and 27th. The explosion can be heard thousands of miles away. The explosion released 2 1 cubic kilometer of volcanic ash and triggered a tsunami of nearly 40 meters, killing about 36,000 people.

The volcanic ash ejected this time rose as high as 657 meters into the air, and the friction with the air also caused lightning and thunder. At the same time, the magma flowed sideways, and the scene was very shocking. After the incident, the Indonesian government has set up a restricted area within 2 kilometers around the volcano.

Santa Maria volcano no.6

Location: Guatemala

Outbreak time: 1902

Volcanic explosivity index: Grade 6.

Lava volume: 20 cubic kilometers

Power: About 69 million Hiroshima atomic bombs.

1902 Santa Maria volcanic eruption is one of the biggest volcanic eruptions in the 20th century. Guatemala volcano was silent for about 500 years after a violent explosion. After the eruption of Santa Maria volcano, a huge crater about 1 mile (1.5km) wide was left in the southwest of the mountain.

1902 on April 23rd, Pei Lei spewed out dust, which surprised the residents greatly. The more dust is sprayed, the more it floats to the city of Saint Pierre, five miles from the crater of Pere. A few days later, the lake on the top of the mountain boiled with geothermal heat, hissed and evaporated a lot of water vapor. It turned out that it flowed down from the mountain, crossed the calm stream of Saint Pierre and became a boiling river. In an instant, the quaint, beautiful and prosperous town of St. Pierre was submerged by fiery volcanic magma and overwhelming volcanic ash. In just two minutes, more than 30,000 people were killed in the fire that erupted in Pei Lei volcano.

No.7 Mitchell volcano

Venue: Papua New Guinea

Outbreak time: 1 100.

Volcanic explosivity index: Grade 6.

Lava volume: 14 cubic kilometer

Power: About 63 million Hiroshima atomic bombs.

The last large-scale eruption of Mount Mitchell was in 1 100 BC. Since then, magma has been piling up, and a large number of magma has crystallized, resulting in an increase in air pressure, so that small-scale eruptions cannot release energy in time. After a large amount of magma found its exit, it was decompressed violently in a short time and released at one time.

Many details about this volcanic eruption are not clear at present, including whether the eruption peak has passed and whether the volcanic system has stabilized after the release of magma pressure. However, according to research, there are many independent eruption events every time facing the "once in a thousand years" eruption.

In fact, on February 9, 20021,19, the volcano erupted, producing a series of explosions, volcanic ash columns and smoke 16 kilometers high, but it was "nothing unusual" for an undersea volcano. In the next few weeks, a large amount of magma expanded the area of the island by nearly 50%.

Green volcano no.8

Location: Iceland

Outbreak time: 1783

Volcanic explosivity index: Grade 6.

Lava volume: 14 cubic kilometer

Power: About 60 million Hiroshima atomic bombs.

Green volcano is a subglacial volcano, similar to most volcanoes in the eastern volcanic area. Green volcano is also distributed in the fault zone, and its direction is southwest-northeast (SW-NE). Coupled with the baking and heating of the mantle plume, Green Volcano has become the most active volcano in Iceland, erupting regularly, just like a sheltered castle in fire and ice.

The eruption of the Grim volcano in 1783 is considered as the largest and deadliest lava jet in history. That eruption killed 9350 people, accounting for almost a quarter of Iceland's population at that time. These deaths are not caused by volcanic lava, but by various indirect causes. The toxic gas and dust emitted by the volcano caused a large number of livestock deaths, and the livestock in Iceland suffered heavy losses. Famine spread all over the country, causing so many deaths.

In addition, the impact of this volcanic eruption is not limited to Iceland. On a global scale, volcanic ash affects the light, the global temperature drops, and the sulfur dioxide content in the northern hemisphere increases, resulting in the reduction of crop production in Europe. Some scientists believe that this volcanic eruption even caused the drought in India. It is estimated that this volcanic eruption killed 6 million people worldwide, making it the deadliest volcano in Iceland.

No.9 Novaru Tower Volcano

Location: Alaska, USA

Outbreak time: 19 12 years.

Volcanic explosivity index: Grade 6.

Lava volume: 13- 15 cubic kilometers

Power: About 58 million Hiroshima atomic bombs.

19 12 Novarupta volcanic eruption was the largest volcanic eruption in the Pacific Ocean in the 20th century. The violent eruption sent 12.5 cubic kilometers of magma and volcanic ash into the air, covering an area of 3,000 square miles (7,800 square kilometers) and the volcanic ash was more than a foot deep. The amount of magma released by this eruption is 30 times that of 1980 San hellens volcano eruption.

10 Mount Pinatubo

Venue: Luzon Island, Philippines

Outbreak time: 199 1 year.

Volcanic explosivity index: Grade 6.

Lava volume: 6- 16 cubic kilometers

Power: About 49 million Hiroshima atomic bombs.