[Causes] the earthquake caused the Earth's surface vibration There are many reasons why, according to the causes of earthquakes, earthquakes can be divided into the following:
1. Tectonic earthquake
Since the depths of underground rock dislocation, caused by the rupture of the earthquake known as tectonic earthquake. Such earthquake occurred most often, the GREatest damage, the earthquake accounted for about 90 percent of the world over.
2. Volcanic earthquake
As the volcano, such as magmatic activity, such as gas explosions caused by the earthquake known as the volcanic earthquake. Only in areas of volcanic activity may occur before the volcanic earthquakes, such earthquakes around the world accounts for only about 7 percent of the earthquake.
3. Earthquake collapse
As the top of underground caves or mine collapse caused by the earthquake known as the collapse of the earthquake. Such relatively small-scale earthquake, the number of little, if any, tend to occur in the limestone cave over the region or large-scale underground mining of the mining area.
4. Induced earthquake
As water, oil field activities such as water flooding caused by the earthquake known as the earthquake-induced. Such earthquake only in certain oil reservoir area or region.
5. Artificial earthquake
Underground nuclear explosions, explosives, blasting and other human-induced ground vibration known as the artificial earthquake. Artificial earthquake was caused by human activities in the earthquake. Such as industrial blasting, the vibration caused by underground nuclear explosions in deep water in a high-pressure water and the large increases the pressure on the crust, sometimes induced earthquake.
The seismic wave origin, called the source. Source on the ground of the vertical projection, called the epicenter. The depth of the epicenter to the source called focal depth. Usually focal depth of less than 70 km of the quake is shallow, deep in the 70-300 km is in the earthquake, the depth is GREater than 300 kilometers of deep earthquakes. Devastating earthquake is generally shallow earthquake. Such as the Tangshan earthquake in 1976 the focal depth of 12 km.
1. Tectonic earthquake
Since the depths of underground rock dislocation, caused by the rupture of the earthquake known as tectonic earthquake. Such earthquake occurred most often, the GREatest damage, the earthquake accounted for about 90 percent of the world over.
2. Volcanic earthquake
As the volcano, such as magmatic activity, such as gas explosions caused by the earthquake known as the volcanic earthquake. Only in areas of volcanic activity may occur before the volcanic earthquakes, such earthquakes around the world accounts for only about 7 percent of the earthquake.
3. Earthquake collapse
As the top of underground caves or mine collapse caused by the earthquake known as the collapse of the earthquake. Such relatively small-scale earthquake, the number of little, if any, tend to occur in the limestone cave over the region or large-scale underground mining of the mining area.
4. Induced earthquake
As water, oil field activities such as water flooding caused by the earthquake known as the earthquake-induced. Such earthquake only in certain oil reservoir area or region.
5. Artificial earthquake
Underground nuclear explosions, explosives, blasting and other human-induced ground vibration known as the artificial earthquake. Artificial earthquake was caused by human activities in the earthquake. Such as industrial blasting, the vibration caused by underground nuclear explosions in deep water in a high-pressure water and the large increases the pressure on the crust, sometimes induced earthquake.
The seismic wave origin, called the source. Source on the ground of the vertical projection, called the epicenter. The depth of the epicenter to the source called focal depth. Usually focal depth of less than 70 km of the quake is shallow, deep in the 70-300 km is in the earthquake, the depth is GREater than 300 kilometers of deep earthquakes. Devastating earthquake is generally shallow earthquake. Such as the Tangshan earthquake in 1976 the focal depth of 12 km.
引起地球表层振动的原因很多，根据地震的成因，可以把地震分为以下几种：
1．构造地震
由于地下深处岩层错动、破裂所造成的地震称为构造地震。这类地震发生的次数最多，破坏力也最大，约占全世界地震的90%以上。
2．火山地震
由于火山作用，如岩浆活动、气体爆炸等引起的地震称为火山地震。只有在火山活动区才可能发生火山地震，这类地震只占全世界地震的7%左右。
3．塌陷地震
由于地下岩洞或矿井顶部塌陷而引起的地震称为塌陷地震。这类地震的规模比较小，次数也很少，即使有，也往往发生在溶洞密布的石灰岩地区或大规模地下开采的矿区。
4．诱发地震
由于水库蓄水、油田注水等活动而引发的地震称为诱发地震。这类地震仅仅在某些特定的水库库区或油田地区发生。
5．人工地震
地下核爆炸、炸药爆破等人为引起的地面振动称为人工地震。 人工地震是由人为活动引起的地震。如工业爆破、地下核爆炸造成的振动；在深井中进行高压注水以及大水库蓄水后增加了地壳的压力，有时也会诱发地震。
地震波发源的地方，叫作震源。震源在地面上的垂直投影，叫作震中。震中到震源的深度叫作震源深度。通常将震源深度小于70公里的叫浅源地震，深度在70-300公里的叫中源地震，深度大于300公里的叫深源地震。破坏性地震一般是浅源地震。如1976年的唐山地震的震源深度为12公里。
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