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A map of epicenters.

An earthquake is the result of a sudden release of energy in the Earth's top 700 km that creates seismic waves. These waves are detected with seismometers and amplified electronically so they can be displayed as a function of time by a seismograph as a seismogram. The size of an earthquake is given by its open ended logarithmic scale of magnitude, often referred to as the Richter scale. Shocks smaller than magnitude 2.5 are usually not felt and those with magnitude 7 cause serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale, ranging from 1 far from the epicenter to a maximum near it, which can reach 12 in the strongest earthquakes..

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabed sometimes is uplifted enough to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity. (read more...)

A propagation of seismic waves.

Seismology (from the Greek seismos (σεισμός) = earthquake and λόγος (logos) = knowledge) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, and artificial processes (explosions). A related field that uses geology to infer information regarding past earthquakes is paleoseismology.

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Sichuan earthquake wenchuan.JPG
The 2008 Sichuan earthquake (Chinese: 四川大地震; pinyin: Sìchuān dà dìzhèn), or "Great Sichuan Earthquake", which measured at 8.0 Ms and 8.3 Mw according to China Earthquake Administration (CEA), and 7.9 Mw according to USGS, occurred at 14:28:01.42 CST (06:28:01.42 UTC) on 12 May 2008 in Sichuan province of China. It was also known as the Wenchuan earthquake (Chinese: 汶川大地震; pinyin: Wènchuān dà dìzhèn), after the earthquake's epicenter in Wenchuan County, Sichuan province. The epicenter was 80 kilometres (50 mi) west-northwest of Chengdu, the capital of Sichuan, with a depth of 19 kilometres (12 mi). The earthquake was felt as far away as Beijing (1,500 kilometres (932 mi) away) and Shanghai (1,700 kilometres (1,056 mi) away), where office buildings swayed with the tremor. The earthquake was also felt in nearby countries.

Official figures (as of July 6, 2008 12:00 CST) state that 69,197 are confirmed dead, including 68,636 in Sichuan province, and 374,176 injured, with 18,340 listed as missing. The earthquake left about 4.8 million people homeless, though the number could be as high as 11 million. It is the deadliest and strongest earthquake to hit China since the 1976 Tangshan earthquake, which killed at least 240,000 people. Approximately 15 million people lived in the affected area.

Did you know...

  • ...that the 1946 Nankaido earthquake caused a 5-6 meter (16-20 feet) tsunami that took out another 2,100 homes after the initial destruction of the earthquake?
  • ...that the 2003 Hokkaido earthquake was not given a cost in US dollars because it occurred offshore and did not cause as much damage as it would have on the mainland of Japan?


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WikiProject Earthquakes is the central point of coordination for Wikipedia's coverage of earthquakes, seismology, tsunamis, and related subjects. Please feel free to join and help!

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