Related topics: tsunami · japan · quake · tectonic plates · earth

Separations between earthquakes reveal clear patterns

When large earthquakes occur, seismologists are well aware that subsequent, smaller tremors are likely to take place afterwards in the surrounding geographical region. So far, however, few studies have explored how the similarity ...

Source of Indonesian earthquakes and tsunamis located

Devastating historical earthquakes and tsunamis in Indonesia can be traced to a recently discovered submarine extensional fault system, where sediment slumping along the fault zone triggers the tsunamis, according to a study ...

Sinking sea mountains make and muffle earthquakes

Subduction zones—places where one tectonic plate dives beneath another—are where the world's largest and most damaging earthquakes occur. A new study has found that when underwater mountains—also known as seamounts—are ...

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An earthquake (also known as a tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacing the ground. When a large earthquake epicenter is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity.

In its most generic sense, the word earthquake is used to describe any seismic event — whether a natural phenomenon or an event caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by volcanic activity, landslides, mine blasts, and nuclear experiments. An earthquake's point of initial rupture is called its focus or hypocenter. The term epicenter refers to the point at ground level directly above the hypocenter.

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