Earthquake
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 this.
Earthquake
USGS Earthquake Hazards Program, responsible for monitoring, reporting, and researching earthquakes and earthquake hazards
Welcome to the U.S. Geological Survey Earthquake Hazards Program
An earthquake 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 ...
Earthquake - Wikipedia, the free encyclopedia
Recent Earthquakes in California and Nevada---> Please visit our reorganized earthquake pages at - http://quake.usgs.gov/--- including new CA-NV pages at - http://quake.usgs.gov ...
Recent Earthquakes in California and Nevada - Index Map
Local earthquake information and activity.
USGS Earthquake Hazards Program-Northern California
The 2008 Sichuan earthquake (simplified Chinese: 四川大地震; traditional Chinese: 四川大地震; pinyin: Sìchuān dà dìzhèn), or "Great Sichuan Earthquake", which ...
