What are earthquakes?

Earthquake or earthquake tremors are sudden and passengers that take place on the Earth's surface caused by underground shocks of rocky plates of the Earth's crust to 300 m below ground. Other reasons are considered gas offsets (mainly methane) and volcanic activity. There are two types of earthquakes: The naturally occurring and induced.

The majority of earthquakes are of natural origin Earth, called tectonic earthquakes. The strength of tectonic plates slide on the atmosphere may move away, collide or slide into one another. With these forces the rocks will changing to its yield point, after which the rocks begin to break down and release accumulated energy during the elastic process. The energy is released through seismic waves on the surface and inside the Earth.

It is estimated that more than 10% of the energy is reproduced by an earthquake seismic waves. There are also induced earthquakes, which are compatible to human action. Originate from explosions, extraction of minerals, water or fossil, or even by falling buildings; but have much lower magnitudes of tectonic earthquakes.

The consequences of an earthquake are:

• Soil Vibration,

• Fault Opening

• Landslide,

• Tsunamis,

• Changes in the Earth's rotation.

In addition to harmful effects to man as injury, death, financial and social damage, buildings collapse etc. The most regions subject to earthquakes are regions near the tectonic plates as the western South America where is located the Nazca plate and the South American plate; and regions which form new plates as in the Pacific Ocean where is the Ring of Fire. The length of a failure caused by an earthquake can vary inches million kilometers, for example, the San Andreas fault in California, USA.

In the US alone there are about 13,000 earthquakes a year ranging from about 18 major earthquakes and a giant earthquake and the others are mild or even unnoticed.

The scale more used to measure the magnitude of earthquakes is the seismologist Charles Francis Richter. Its scale ranges from 0 to 9 degrees and calculates the energy released by earthquakes. Another commonly used scale is the Mercalli-Sieberg, which measures the extent of the damage by earthquakes. This range is divided into 12 categories according to their intensity.

Earth Planet

Last Update: 27/03/2015