Earthquakes are vibrations of the earth's surface caused by tremors of natural (tectonic processes) or artificial origin. Small earthquakes can occur during volcanic eruptions.
Instructions
Step 1
An earthquake is a fairly frequent occurrence on our planet. Despite the fact that every year about a million of these activities occur on Earth, most of them go unnoticed. Earthquakes occur about once every two weeks, which can cause serious damage. Fortunately, most of them have their epicenters at the bottom of the oceans. In this case, only tsunamis caused by tremors can cause at least some damage.
Step 2
There is a special system that records earthquakes that do not occur on the surface of the entire planet, including the most insignificant of them. Usually the cause of earthquakes is the displacement of an area of the earth's crust. Most of the foci are located near the Earth's surface.
Step 3
The epicenter of an earthquake is usually called the area on the surface of the planet, located above the source. During an earthquake, seismic waves radiate from the source. Their propagation speed can reach eight meters per second.
Step 4
Usually earthquakes are classified according to their intensity. There are special scales by which this indicator is determined. All of them are a modification of the original Medvedev-Sponheuer-Karnik scale. As a rule, a twelve-point intensity system is used. An earthquake recorded only by a seismograph gets 1 point, i.e. unreplaceable for people. 12 points - this is a major change in relief and widespread destruction of buildings.
Step 5
A seismograph is a device that records the types of seismic waves and registers their intensity. These devices are of mechanical and electronic type. Artificial earthquakes are phenomena caused by human intervention. This could be a large underground explosion, which later led to the displacement of the plates.
