Earthquake

By Win Sein

An earthquake is what is happen when two blocks of the earth suddenly slip past one another, the sur­face where they slip is called the fault or fault plane. So, an earth­quake refers to the shaking of the earth’s surface caused by a sudden release of energy within the earth’s crust. The release of energy generates seismic waves commonly known as S waves. The intensity and characteristics of an earthquake are determined by the seismic activities in a spe­cific region.

In another way, we may say that vibrations generated by an earthquake and propagated with­in the earth or along its surface, are seismic waves. There are four principal types of elastic waves: -two, primary and secondary waves, travel within the earth, whereas the other two, Rayleigh and Love waves called surface waves can be produced artificial­ly by explosion. A fault is a frac­ture or zone of fracture between two blocks of earth. Fault allows the blocks to move relative to each other. This movement may occur rapidly, in the form of creep

About 50,000 earthquakes large enough to be noticed and without aid instruments, occur annually over the entire earth. Of these, approximately 100 are of sufficient size to produce sub­stantial damage if their centres are near areas of habitation. Very great earthquakes occur on an average of about once per year. Over the centuries they have been responsible for millions of deaths and incalculable damage to property.

A separate type of earth­quake is associated with volcanic activity and is called a volcanic earthquake. Yet it is likely that even in such cases the distur­bance hums the result of a sud­den slip of rock masses adjacent to the volcano and the conse­quent release of elastic strains energy. The stored energy may in part be of hydrodynamic origin due to heat provided by magma moving in reservoirs beneath the volcano or to the release of gas under pressure. There is a clear correspondence between the geographic distribution of vol­canoes and major earthquakes particularly in the Pacific.

The largest earthquake re­corded by seismic instruments anywhere on earth was a mag­nitude of 9.5 earthquake in Chile on 22 May 1960. That earthquake occurred on a fault that is about 1,000 miles long and 150 miles wide. Dipping into the earth at a shallow angle, the magnitude scale is open-ended, meaning that scientists have not put a lim­it on how large an earthquake could be but there is a limit just from the size of the earth.

The Myanmar Earthquake Committee was founded in 1999 and conducted seismological re­search on active fault lines and past earthquakes in Burma. Until significant earthquakes hit the country in the last few years, in­cluding a 6.8-magnitude quake in Bagan this year. The committee has seven seismic academics. The Committee has produced seismic hazards maps for My­anmar.

The 1930 Bago earthquake struck Burma in May. Extensive damages were reported in the Southern part of the country, par­ticularly in Bago and Rangoon, where buildings collapsed and fire erupted in many locations. At least 550 and possibly up to 7,000 people were killed.

There are multiple reasons why predicting earthquakes is difficult. Even the scientists do have a good understanding of how the disaster occurred. The eruption of an earthquake is not as able as the present scientists when going for predicting a great storm before the natural disaster of a cyclone or storm is about to take place. there is bound to be a low-pressure centre in exist­ence around thunderstorms, pro­ducing strong wind and flooding rain. Tropical cyclones form over warm waters from pre-existing disturbances. These pre-existing signs and behaviours would lead the disaster watchers to predict the disaster would happen in a week or two weeks’ time. In the case of an earthquake, there are no such pre-existing signs to guide them in the search. The only way to predict a great earthquake is to record its last occurrence in a year or month for preparations plan to review its reoccurrence in the future. In order to pinpoint exactly the magnitude of the disaster is out of the question.