Related topics: quake · earthquake

Stress in Earth's crust determined without earthquake data

Scientists at Los Alamos National Laboratory have developed a method to determine the orientation of mechanical stress in the earth's crust without relying on data from earthquakes or drilling. This method is less expensive ...

Volcano erupts on Spain's Canary Islands

The Cumbre Vieja volcano erupted on Spain's Canary Islands Sunday, spewing out lava, ash and a huge column of smoke after days of increased seismic activity and forcing the evacuation of around 5,000 local people, authorities ...

The seismic zone worrying quake-hit Mexico

A 7.1-magnitude earthquake that struck southern Mexico this week originated near a section of a fault that experts worry has been building up tension for more than a century.

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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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