Apr 18 2010
Earthquake Facts
Earthquakes are one of the most dangerous of natural calamities.An earthquake occurs due to the strain put on the ground by the tectonic plates when they get stuck. When this strain increases, the rocks give way and this results in an occurrence of fault lines.The earthquake results in the sudden release of the stored energy in the Earth’s crust. This creates seismic waves and results in the shaking or a displacement of the ground.Earthquakes can cause shaking and ground rupture,fires, soil liquefaction, landslides and avalanches and tsunamis.
The recent earthquake related tsunami took place in 2004 in the Indian Ocean. The earthquake occurred within the sea, which in turn triggered a large number of tsunamis along the borders of the Indian Ocean. The tsunamis struck Sri Lanka, Indonesia, India and Thailand.
Further, earthquakes can also cause loss of life, disease, loss of basic amenities, property damage, as well as road and bridge damage, building collapses or the destabilization of the base of the building. Therefore, earthquakes result in personal as well as economic losses.
Seismologists depend on the seismogram, numeric modeling and other geodetic measurements to measure the capacity of magnitude of the earthquakes. Therefore, ‘magnitude’ is the quantitative expression of the earthquake, while the shaking capacity of the earthquake is called ‘intensity’. The location below the Earth’s surface, where the rupture of the fault begins is known as the hypocenter. The point directly above the hypocenter on the surface of the Earth is known as the epicenter.
There are about five hundred thousand detectable earthquakes globally every year. While a ten thousand of these can be felt, a hundred can cause serious damage. Most of the earthquakes occur at a distance of fifty miles from the Earth’s surface.The earliest earthquake was recorded in the Shandong province of China back in 1831 BC.
The most earthquake prone zone in the world is Alaska. It is one of the most seismically active zones in the world. Alaska experiences a magnitude eight or greater earthquake every fourteen years, and a magnitude seven earthquake almost every year.In the year 1960, during the Chilean earthquake, the seismic waves traveled around the globe for many days. This is known as free oscillation of the earth. The interiors of Antarctica have a phenomenon similar to earthquakes, known as the icequakes. The icequakes occur within the ice sheet, instead of the land under the ice sheet.
The first earthquake in America was experienced in 1663 by the European settlers. The largest recorded earthquake in the United States of America struck Prince William Sound, Alaska on March 28. The magnitude of the earthquake was 9.2. Florida and North Dakota have the smallest amount of earthquakes in the United States of America The largest recorded earthquake in the world was in Chile in 1960. The magnitude of the earthquake was 9.5.
The Southern Californian region has about ten thousand earthquakes every year. However, many of them are small and are not felt. Rarely any of them are above magnitude three and a few are above magnitude four. Therefore, earthquakes occur almost everyday in California. Such
earthquakes also occur in Indonesia, Japan and Azores in Portugal.
The majority of earthquakes occur along the plate boundaries. The Pacific Plate is known as the Pacific Plate of Fire because it is one of the most active plate boundaries where earthquakes as well as eruptions are frequent.
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