What is volcanism and earthquakes? Where do these phenomena occur?

Volcanism and earthquakes are one of the oldest processes on Earth. They occurred billions of years ago and continue to exist in our days. Moreover, they participated in the formation of the relief of the planet and its geological structure. What is volcanism and earthquakes? We will talk about the nature and places of occurrence of these phenomena.

What is volcanism?

Once upon a time our whole planet was a huge hot body, where alloys from rocks and metals were boiling. In hundreds of millions of years, the upper layer of the Earth began to harden, forming a thickness of the earth's crust. Under it, molten substances or magma still bubbled.

Its temperatures reach from 500 to 1250 degrees Celsius, which causes the hard parts of the planet's mantle to melt and gases are released. At certain moments, the pressure here becomes so great that the hot fluid tends to literally break out.

What is volcanism? This is the vertical displacement of magma flows. Rising up, it fills the cracks of the mantle and the earth's crust, splits and raises hard layers of rocks, punching their way to the surface.

Sometimes the liquid simply freezes in the earth's thickness in the form of laccolites and magmatic veins. In other cases, it forms a volcano - usually a mountainous formation with a hole through which magma spills out. This process is accompanied by the release of gases, rocks, ash and lava (liquid rock melt).

Varieties of volcanoes

Now that we've figured out what volcanism is, let's look at the volcanoes themselves. All of them have a vertical channel - a vent on which magma rises. At the end of the channel is a funnel-shaped hole - a crater, a few kilometers in size and up.

The shape of the volcanoes differs depending on the nature of the eruptions and the state of the magma. Under the action of a viscous liquid, dome formations appear. Liquid and very hot lava forms volcanoes of a thyroid form with gentle slopes resembling a shield.

Multiple eruptions form slag and stratovolcanoes. They have a cone shape with steep slopes and grow in height with each new eruption. There are also complex or mixed volcanoes. They are asymmetrical and have several crater vertices.

Most eruptions form positive reliefs protruding above the earth's surface. But sometimes the walls of the craters collapse, in their place appear vast hollows a few dozen kilometers in size. They are called calderas, and the largest of them belongs to the volcano Toba on the island of Sumatra.

The nature of earthquakes

Like volcanism, earthquakes are associated with internal processes in the mantle and the earth's crust. These are powerful tremors that shake the surface of the planet. They arise as a result of volcanoes, mountain landslides, as well as movements and uplifts of tectonic plates.

In the hearth of the earthquake - the place where it is born - the tremors are the strongest. The farther away from him, the shake is less perceptible. The consequences of earthquakes are often destroyed buildings and cities. During the seismic activity, landslides, landslides and tsunamis may occur.

The intensity of each earthquake is determined in points (from 1 to 12), depending on its scale, damage and nature. The easiest and inconspicuous jerks are given 1 point. A shake of 12 points leads to uplifts of individual sections of the terrain, large faults, and destruction of settlements.

Zones of volcanism and earthquakes

The complete geological structure of the Earth from the earth's crust and to the core itself is still a mystery. Most of the data on the composition of the deep layers are just assumptions, because no one has been able to look further than 5 kilometers into the bowels of the planet. Because of this, it is impossible to predict the eruption of another volcano or the appearance of an earthquake in advance.

The only thing that researchers can do is to identify areas where these phenomena occur most often. They are clearly visible in the photo, where a light brown color indicates weak activity, and a dark color indicates a strong activity.

They usually occur at the junction of lithospheric plates and are associated with their movement. The two most active and extended zones of volcanism and earthquakes are the Pacific and Mediterranean-Trans-Asian belts.

The Pacific belt is located along the perimeter of the ocean of the same name. Here, two-thirds of all eruptions and earthquakes occur on the planet. It stretches for 56 thousand kilometers in length, covering the Aleutian Islands, Kamchatka, Chukotka, the Philippines, the eastern part of Japan, New Zealand, the Hawaiian Islands, the western hemisphere of the North and South America.

The Mediterranean-Trans-Asian belt stretches from the ridges of Southern Europe and North Africa to the Himalayan mountains. It includes Kun-Lun and Caucasus mountains. About 15% of all earthquakes occur within it.

In addition, there are secondary zones of activity, where only 5% of all eruptions and earthquakes occur. They cover the Arctic, the Indian (from the Arabian Peninsula to Antarctica) and the Atlantic Ocean (from Greenland to the Tristan da Cunha archipelago).