What is an earthquake?

What is an earthquake?

An earthquake is a sudden oscillation of the earth's surface caused by earthquakes. Often people, especially those who do not live in seismically dangerous regions, are mistaken, believing that under their feet there is a monolithic unbreakable firmament. But in the bowels of the planet there are constantly numerous processes, tectonic plates are shifting, approaching and pressing on each other. As a result, energy accumulates in the Earth's thickness for a long time. And one day it is released, causing an earthquake. Scientists have established that the amount of energy released is several thousand times greater than the energy of an atomic bomb, so it is not surprising that an earthquake is accompanied by colossal destruction.

Ninety per cent of the foci of all major earthquakes occur in seismically active areas where the edges of lithospheric plates converge , but sometimes destructive energy can break out where people do not know what an earthquake is. Virtually in any country, regardless of geographical location and climatic conditions, and at any time of the year, tremors can be felt. The largest earthquakes scientists-seismologists can predict in advance, but it is impossible to prevent them.

How to measure an earthquake?

What is an earthquake is clear, but how to measure it? For this, there are two basic concepts: magnitude and intensity. Magnitude shows the strength of the oscillations in the epicenter of the tremors. This value is important for seismologists, but little will tell ordinary people, because the tremors with a large magnitude that occurred in the mountains and desert areas will not be particularly devastating. For us, the intensity measured in points, which characterizes the strength of the above-ground manifestations of the earthquake, is more important.

Types of earthquakes

Depending on the reasons for which there are earthquakes, several types of earthquakes are singled out.

The most common are tectonic earthquakes. They are caused by faults, collisions and movements of tectonic plates. Weak tremors, which are recorded continuously, on the surface are practically not felt. Strong ones cause the appearance of huge cracks, landslides and landslides on the surface of the earth. After themselves, they leave colossal destruction. Earthquakes in the sea cause a tsunami and a huge tidal wave.

Virtually no destruction is left behind by volcanic earthquakes, caused by volcanic eruptions. They can be repeated many times until the volcano ceases to function. But from time to time wake up and "sleeping" volcanoes.

In the mountains often there are landslides and landslides, which cause landslide earthquakes, which do not have great strength. This is due to the occurrence of voids inside the mountains and underground.

People have a constant impact on the planet and the environment. We build dams, artificially change the riverbeds, turn the mountains into plains, drill mines, extracting minerals. This can not but cause consequences, so it is not surprising that such an earthquake as man-caused is provoked by the actions of the person himself.

Another type of earthquake is artificial, caused by underground tests of new types of weapons or arising from nuclear and other explosions.