earthquake is the result of a sudden release of energy in the Earth"s crust that creates seismic waves（地震波）. Earthquakes are recorded with a seismometer（地震检波器）, also known as a seismograph（地震仪）. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude(里氏量级）, with magnitude 3 or lower earthquakes being mostly imperceptible 感觉不到的 and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale（麦加利震级, 麦氏震级）.
At the Earth"s surface, earthquakes manifest themselves by a shaking and sometimes displacement （位移）of the ground. When a large earthquake epicenter （震中）is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami（海啸）. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity.
