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Earthquakes can rip apart entire cities and outlying districts, as the 1995 disaster in Kobe, Japan showed. SeismoLogists, scientists who study earthquakes and related phenomena, have records dating back to 1556, from the Chinese province of Shaanxi, which indicate that earthquakes have been devastating our world for centuries.
The destructive forces which produce earthquakes usually begin deep below the ground, along a fault in weaker areas of the earth’s rocky outer shell, where sections of rock repeatedly slide past each other. As the fracture extends along the fault, blocks of rock on one side of the fault may drop down below the rock on the other side, move up and over the other side, or slide forward past the other. The violent shattering of rock releases energy that travels in waves, and these seismic waves move out from the focus of the earthquake in all directions. As the waves travel away from the focus, they grow gradually weaker, generally resulting in the ground shaking less as distances increase.
Geological movements are not the only occurrences to trigger an earthquake. Human activity, most often the filling of reservoirs with extraordinarily large amounts of water, can also cause earthquakes. Similarly, massive explosions can wreak havoc, too.
Earthquakes almost never kill people directly. Instead, many deaths and injuries result from falling objects and collapsing buildings, while fire resulting from broken gas or fallen power lines is another danger. The Kobe earthquake in January 1995 lasted only 20 seconds, yet resulted in a death toll of over 5,000 and injured approximately 26,000 people.
Even though earthquake prone countries spend enormous human and financial resources on seismographic measurement, as a means of predicting earthquakes, there is a danger in paying too much heed to seemingly high risk zones and erecting less stable buildings solely because of their being in a low risk zone. Prior to the earthquake, Kobe was not regarded as at serious risk, but after the disaster, investigation of the damage revealed that nearly all deaths occurred in small buildings shattered rather than twisted when stressed. Coupled with the problem of soft soils, the buildings had little firm support and many crumbled. If countries wish to withstand the devastating forces of substantial earthquakes and reduce death, injury and property damage, it is important to design and construct buildings that are earthquake resistant, as well as monitor seismic forces.
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