an 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.
in its most generic sense, the word earthquake is used to describe any