Earthquakes

Earthquake is the most terrible natural disaster. It has more destruction ability than the other disasters. People can’t do anything against it. If we look at the earthquake from scientific view. It is very interesting event. It is prov

Earthquake is the most terrible natural disaster. It has more destruction ability than the other disasters. People can’t do anything against it. If we look at the earthquake from scientific view. It is very interesting event. It is provoked by several reasons: volcanoes, explosions and so on. But the earthquakes caused by them are very weak. The processes that happen in litosphere of the earth generally provoke strong earthquake in. According to the “theory of piles”. Lithosphere consists of some big piles and this lithosphere piles move in relation with each other. There is 6 big continental size and 14 smaller piles. The pile movement provoke the deformations of its border lines. This deformation is the reason of earthquake. This is the reason of the most earthquakes, which happened on the borders of piles and micro piles. Some of the earthquakes are so weak that people can’t notice them. Some are so strong that they are followed by big destruction. In 1988 year in Spitaki , the city of Armenia happened strong earthquake. 25000 people died and 500000 became homeless. The loss of the earthquake that happened in Nortrij 1994 year was 50 billion USD. In 1995 in Kobe in Japan happened earthquake that had 200 million loss. The last strong earthquake happened in Turkey 1999 year. At the time of this earthquake 14000 people died. As we saw earthquake have big loss. In order to get prompt information about earthquake strength, scientists measure its surface effect and energy. Surface effect is called earthquake intensity as well. Today intensity is measured with several scales. Most of the modern scales include 12 points. Mercal Modificated (MM) scale is very popular in the USA and other English countries. Japan uses different scales, which consist of 7 points. The scales are based on easy descriptions of earthquake effects so that nonprofessional people can evaluate its intensity. We can’t talk about earthquake only with its intensity. Seismologists measure its energy as well in order to better estimation its strength. In 1935 American scientist Churls Rikhter created new method of earthquake estimating. He invented the Magnitude scale. Scientists measured the energy of earthquake with this scale and it is very popular today. It is called Rikhter scale as well. Magnitude is relative unit. There is the standard earthquake magnitude and the energy logarithmically depends on magnitude (Log=1.5M+11.8 M is a magnitude, E is energy in argues). The magnitude raised of one point is equal to energy rising 31.6 times. The strongest earthquake was in 1960-Chile earthquake. M=9.5 and in 1964 “Alaska earthquake”. In the Chile the ground hole made by the earthquake was 1000 kilometers long. The energy was 1025. It is equal to 1000 nuclear bomb explosion. We can say that earthquake is strong if its magnitude is more than six points and it can provoke big destruction. Seismology is the science that studies earthquakes. The oldest letters about the earthquakes are written in about 2000 years B.C. After that seismology was developing. But in order it needs developing of math, physics, and geology and so on to develop this science. This is the main reason why seismology had not had important results until the 19th century. In the 19th century science made the first seismograph, created the first scale and began measuring of intensity and magnitude. Today we cannot predict the earthquake and we will never stop earthquakes. But seismology developing helps us to get less destruction. So the efforts of seismologists are very important for the world. Автор: Александър Ненов