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 . 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 a shaking and sometimes displacement of 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 means the point at ground level directly above this.
地震的能量突然釋放的結果創造了地震波在地殼中。地震檢波器記錄,也稱為地震儀。地震的矩震級是常規報道,或相關的,大多是過時的里克特震級,3級或低主要是無法察覺的,7級地震導致大面積嚴重損害。震動強度是衡量麥式震級范圍修改。
顯現在地球的表面,地震的震動,有時位移。當大地震震中位于海外,海底有時會出現足夠的位移導致海嘯。地震的震動也能引發山體滑坡和偶爾的火山活動。
在其最一般的意義上說,“地震”這個詞是用來描述任何地震event-whether自然現象或一個事件引起的人類產生地震波。地震是主要由地質斷層破裂引起的,但也受到火山活動,山體滑坡,我的爆炸,核的實驗。
地震的初始破裂稱為它的焦點或震源。這個詞意味著中心指向地面的正上方。
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