There is a large amount of high-temperature liquid at a depth of about 32 kilometers from the ground, and its temperature is enough to melt most rocks.
When rocks melt, they expand and need more space. In some parts of the world, mountains are rising. The pressure under these rising mountains is reduced, and a lava pool may form under these mountains.
This substance rises along the cracks caused by the uplift. When the pressure in the lava dome is greater than the pressure on the top of the rock above it, it rushes out of the fragile crust and becomes a volcano in the process of formation.
When erupting, hot gas, liquid or solid substance suddenly comes out. These substances are piled up around the opening, forming a cone-shaped hill that passes through the "crater", which is a depression at the top of the volcanic cone, and the opening leads to the surface. This cone-shaped mountain is the product of volcanic formation. The material ejected by the volcano is mainly gas, but it also ejects a lot of volcanic rocks and solid materials such as slag and ash. In fact, volcanic rocks are magma erupted by volcanoes. When the magma rises to a height close to the surface, its temperature and pressure begin to drop, and physical and chemical changes have taken place, and the magma becomes volcanic rock.
Question 2: How is volcanic eruption formed? ■ Why is there a volcanic eruption?
It turns out that the magma temperature inside the earth is very high, and the temperature near the center is as high as 4000℃. It can flow like molten iron in steelmaking. With the increase of the temperature inside the earth, these gas-rich magma always wants to be ejected from time to time like cooking porridge.
If the crust is compared to a "pot cover", then the pressure on the crust is very great, and it is not so easy for magma to open this "pot cover" and rush out. Therefore, on the one hand, magma should gather energy, on the other hand, it should choose places with weak crust and cracks in the crust as gaps to rush out. With the evolution of gas in magma, the internal pressure increases and the activity strengthens. When the gas pressure reaches a certain limit, the magma will break through the "cover" and go straight into the sky. Like a fiery snake rushing to the ground, heaven and earth seem to have returned to the flood period, which is the volcanic eruption.
Question 3: How did volcanic lava form? The rocks on the earth can be divided into three categories: igneous rocks, sedimentary rocks and metamorphic rocks. Lava belongs to the category of igneous rocks
Because magma is produced in the mantle and lower crust. At this time, it was liquid. Because of the great pressure, I kept looking for cracks in the earth's crust and rushed up. When it becomes a rock, it must pass through the earth's crust so far. Sometimes, it doesn't come up enough, so it becomes plutonic. The point that rushes up, but does not reach the surface, becomes shallow diagenesis; Then more powerful from the volcanic tunnel or crater spewed out of the surface, becoming spewed rocks. Among them, plutonic rocks and hypabyssal rocks are called intrusive rocks in the introduction to earth science.
Lava is an eruptive rock, which is based on the occurrence of eruptive rock (occurrence is simply the state of formation). The occurrence of eruptive rocks can be divided into volcanic cones, lava flows, lava waterfalls and rock caps (also known as lava caps).
Secondly, from the composition of lava, we are actually talking about the composition of magmatic rocks, or, nonstandard, igneous rocks. Then from the perspective of silica, sodium oxide and potassium oxide, according to this standard, it can be divided into ultrabasic rocks, basic rocks, intermediate rocks, acid rocks and alkaline rocks. As we have said just now, igneous rocks can be divided into intrusive rocks (plutonic and hypabyssal) and extrusive rocks, so their names should also be divided. We only talk about extrusive rocks. In lava, that is, extrusive rocks, there are picrite, basalt, andesite, rhyolite, trachyte and so on. So, when watching a movie, how do we know what rock is? This requires professional training. Of course, there is a simple way. Acidic magma flows slowly, and fast flow is basic, because the viscosity is different from the temperature of magma itself. This is why there are pillars and needles in Huangshan Mountain. Granite is acidic magma, which flows slowly and then solidifies as soon as it is ejected. This will not happen to basalts (basic rocks) such as Mount Emei.
Finally, back to the most basic question, since lava is extracted from the concept of magma, how is magma formed? All kinds of rocks are melted by high temperature in the deep underground and return to the interior of the earth in the form of magma. I can only answer you with this simple answer. Because it involves plate movement and petrology.
As for plate movement, we can see from the Pacific plate that magma gushes from the mid-ocean ridge and then pushes the plate to the edge. At the junction of Eurasia and the Pacific plate, our Eurasia plate forbeared to let it dive because it moved. What about the rocks that swooped down? It melted into magma in the deep, and then compensated in the middle of the Pacific Ocean, which became a cycle. I only give this example to illustrate the conservation of matter and part of the process of magma formation. Because magma is not necessarily formed by igneous rocks, it may be metamorphic rocks or sedimentary rocks, and this petrological migmatite can be understood in detail.
Question 4: How did volcanoes form? The picture shows that the crust is squeezed and collides with the gap, and the magma inside the earth is under pressure, erupting from the gap and accumulating after the ground cools.
Question 5: How did volcanoes form? According to the loss of human life, the most destructive volcanic eruption in the 20th century occurred in1May 902 on Martinique Island in the West Indies. There were several small earthquakes in April that year, which should be regarded as early warning. A few days later, at 7: 50am on May 8th, four explosions shook Martinik Island. At the same time, the crater of Cabbage Mountain also spewed a mass of burning gas and ash, emitting a red light. After a while, more gas, dust and volcanic ash spewed out from the cracks on the side of the volcano and rolled down the mountain at an alarming speed. However, the city of St. Bill was flooded in more than a minute, and only one of the 30 thousand residents survived.
The outbreak of Bai Caishan will remain in the history of human suffering forever. But as far as the power played by nature is concerned, volcanic eruptions have become more violent in recent decades. For example,1On March 30th, 956, the Unknown Mountain in kamchatka peninsula, Siberia erupted 4.4 billion tons of rock-enough to bury a city as big as Paris under a 32-foot-thick gravel layer. According to a witness in a town/0/25 miles east of Unknown Mountain, a large black smoke covered the horizon and went straight into the sky for 22 miles. Volcanic ash scattered on the ground 250 miles away. However, no one died in this volcanic eruption. Why? The main reason is that there are few residents in that area; Part of the reason is that volcanologists in the former Soviet Union predicted that this unknown mountain would erupt months ago.
The former Soviet Union did not have a volcano observatory in the towering Klyuchevskaya Mountains. Since September 1955, a series of strong earthquakes have occurred in the local area. Scientists found from the seismogram that the earthquake hit the nameless mountain at an altitude of 10 12 1 ft, and it was considered as an extinct volcano for a long time. From122 October, this unknown mountain began to spew volcanic ash and condense into a cauliflower-shaped smoke. 1 1 month 17, volcanic ash landed in the village of kliuqi, 28 miles away, blocking the sun and driving first class during the day. The crater kept spewing black smoke until it exploded in March of the following year. Then, the volcanic activity gradually subsided and stopped completely after eight months.
Unknown Mountain is a part of the "Ring of Fire". This ring of fire is a volcanic belt around the Pacific Ocean, from Chile in South America to Peru in the north, and then to the west coast of Mexico and North America, including Mount Shasta in California, Mount Hood in Oregon and Mount Rainier in Washington State. Turn west in Alaska, cross the Aleutian Islands, and then turn around and cross the kamchatka peninsula. It passes through the Kuril Islands in Okhotsk, Japanese Islands, Philippine Islands, east indies, New Guinea and New Zealand. Of the 529 active volcanoes in the world, 42 1 is located on the edge or ring of the volcano. The arc-shaped volcanic belt of the Caribbean Islands is generally considered as a branch of this ring of fire.
Another less dangerous volcanic belt starts from Testonda Kongya in the South Atlantic, extends along the submarine mountains in the middle of the Atlantic, and goes north to Iceland via the Azores. There are 28 active volcanoes in Iceland alone. There are Suwell Volcano, Adela Volcano, Strombo Volcano and Urkona Volcano in the Mediterranean. However, the most powerful volcanoes are in the volcanic ring of the Pacific Ocean. On the edge of this fireworks circle, most of them are densely populated areas. Indonesia has 78 active volcanoes; There are 47 in Japan, most of which are near big cities; There are thirty-seven in the United States, mostly in Alaska and the Aleutian Islands.
In Japan, volcanology, the science of studying volcanic activity, is of great practical value. Japan has the largest number of volcanologists, 60 of whom are world famous. One of the best volcanological research institutions in the world is located at the Federal Volcano Observatory in Kilauea, Hawaii. Kilauea volcano is 4090 feet above sea level and rises 20000 feet from the bottom of the sea? Alien volcano The adjacent Chanaloa Peak is 13680 feet above sea level and is the largest active volcano in the world today. In fact, Channa Loa and neighboring Channa Kaiya are the highest peaks in the world, because the height of these two peaks is about 30,000 feet directly from the bottom of the sea. Mount Everest is only about fifteen thousand feet from the bottom of the plateau. )
As far as the goal of academic research is concerned, Mount Mauna Loa and Mount Kilauea on Hawaiian Island are the best places. The local climate is good, and observation and research can be carried out all year round, while scientists only need half an hour's flight from Honolulu. These two craters are often active; Outbreaks of diseases are frequent, usually mild and usually predictable. On the edge of Kilauea volcano >>