What is an earthquake?
Earthquake - a sudden fluctuation of the Earth's surface caused by the tremors.Most people, especially those not living in seismically dangerous regions mistaken, believing that under their feet is unbreakable monolithic firmament.But in the depths of the planet are constantly occur numerous processes tectonic plates shifted, closing in and press against each other.As a result, the thickness of the earth for a long time accumulates energy.And once it is released, causing an earthquake.Scientists have found that the amount of energy released in a few thousand times the energy of an atomic bomb, it is not surprising that the earthquake followed by huge devastation.
Ninety percent of the centers of all major aftershocks occur in seismically active areas, where converge the edge of the lithospheric plates, but sometimes destructive energy can escape where people do not know what an earthquake.In almost every country, regardless of geographic location and climatic conditions, and at any time of the year can be felt the tremors.The largest earthquake seismologists can predict in advance, but it is impossible to prevent them.
How to measure an earthquake?
What is an earthquake, it is clear, but how to measure it?For this there are two basic concepts: the magnitude and intensity.Magnitude shows the strength of fluctuations in the epicenter of the tremors.This value is important for seismologists, but few will say that the ordinary people, because a large magnitude aftershocks occurred in the mountains and desert areas will not be particularly devastating.For us it is more important than the intensity, measured in points, which characterizes the strength of the aerial displays of the quake.
Types earthquakes
Depending on the reasons for which there are tremors, identify several types of earthquakes.
most common - tectonic earthquakes.They are caused by faults, collisions and advances of tectonic plates.Weak tremors that are recorded continuously at the surface hardly felt.Strong becomes the cause of the earth's surface the huge cracks, landslides and avalanches.They leave behind a colossal failure.The earthquake caused a tsunami in the sea and a huge tidal wave.
Virtually no damage does not leave behind a volcanic earthquake is caused by volcanic eruptions.They can be repeated as long as the volcano is no longer operate.But from time to time and wake up "sleeping" volcanoes.
The mountains are frequent avalanches and landslides that cause landslip earthquake without great force.This happens because an inside mountains and underground cavities.
People have a permanent impact on the planet and the environment.We build dams, artificial riverbeds change, transform the mountains into the plains, we are drilling shafts, carrying mining.This should cause the consequences, so it is not surprising that such an earthquake as man-made, provoked by the actions of the man himself.
Another type of earthquake - artificial, caused by the underground tests of new weapons or arising from nuclear and other explosions.
