What is an earthquake?
An earthquake is a sudden wobble of the earth's surface caused by tremors. Often people, especially those who do not live in seismically dangerous regions, are mistaken, believing that under their feet is a monolithic indestructible firmament. But numerous processes constantly occur in the bowels of the planet, tectonic plates are displaced, pushed and push against each other. As a result, energy is accumulated in the thickness of the Earth for a long time. And once it is released, causing an earthquake. Scientists have found that the amount of energy released is several thousand times greater than the energy of an atomic bomb, so it is not surprising that the earthquake is accompanied by tremendous destruction.
Ninety percent of the centers of all major tremors occur in seismically active areas where the edges of lithospheric plates converge, but sometimes destructive energy can escape where people do not know what an earthquake is. In almost any country, regardless of geographic location and climatic conditions, and at any time of the year tremors can be felt. Seismologists can predict the largest earthquakes in advance, but they cannot be prevented.
How to measure an earthquake?
What is an earthquake, clearly, but how to measure it? There are two main concepts for this: magnitude and intensity. Magnitude shows the strength of vibrations in the epicenter of tremors. This value is important for seismologists, but it will say little to ordinary people, because tremors with great magnitude that occurred in the mountains and desert areas will not be particularly destructive. For us, the intensity measured in points, which characterizes the strength of the above-ground manifestations of the earthquake, is more important for us.
Types of Earthquakes
Depending on the reasons why tremors occur, several types of earthquakes are distinguished.
The most common are tectonic earthquakes. They are caused by faults, collisions and movements of tectonic plates. Weak shocks, which are recorded constantly, are practically not felt on the surface. The strong ones cause huge cracks, landslides and landslides to appear on the surface of the earth. After themselves, they leave enormous destruction. Earthquakes in the sea cause a tsunami and a huge tidal wave.
Volcanic earthquakes caused by volcanic eruptions leave virtually no damage. They can be repeated many times until the volcano ceases to function. But from time to time waking volcanoes also wake up.
In the mountains, landslides and landslides often occur, which cause landslide earthquakes that are not very powerful. This happens due to the appearance of voids inside the mountains and underground.
People have a constant impact on the planet and the environment. We build dams, artificially change river channels, turn mountains into plains, drill mines, and mine. This cannot but cause consequences, therefore it is not surprising that such an earthquake, as a man-made one, is provoked by the actions of the person himself.
Another type of earthquake is artificial, caused by underground testing of new weapons or resulting from nuclear and other explosions.
