【概述】
地震(earthquake)就是地球表层的快速振动，在古代又称为地动。它就象刮风、下雨、闪电、山崩、火山爆发一样，是地球上经常发生的一种自然现象。 它发源于地下某一点，该点称为震源(focus)。振动从震源传出，在地球中传播。地面上离震源最近的一点称为震中，它是接受振动最早的部位。大地振动是地震最直观、最普遍的表现。在海底或滨海地区发生的强烈地震，能引起巨大的波浪，称为海啸。地震是极其频繁的，全球每年发生地震约500万次，对整个社会有着很大的影响。【地震的产生】
地震是地球内部介质局部发生急剧的破裂，产生地震波，从而在一定范围内引起地面振动的现象。地震开始发生的地点称为震源，震源正上方的地面称为震中。破坏性地震的地面振动最烈处称为极震区，极震区往往也就是震中所在的地区。【地震现象】
地震发生时，最基本的现象是地面的连续振动，主要是明显的晃动。极震区的人在感到大的晃动之前，有时首先感到上下跳动。这是因为地震波从地内向地面传来，纵波首先到达的缘故。横波接着产生大振幅的水平方向的晃动，是造成地震灾害的主要原因。1960年智利大地震时，最大的晃动持续了3分钟。地震造成的灾害首先是破坏房屋和构筑物，造成人畜的伤亡，如1976年中国河北唐山地震中，70％～80％的建筑物倒塌，人员伤亡惨重。地震对自然界景观也有很大影响。最主要的后果是地面出现断层和地裂缝。大地震的地表断层常绵延几十至几百千米，往往具有较明显的垂直错距和水平错距，能反映出震源处的构造变动特征（见浓尾大地震，旧金山大地震）。但并不是所有的地表断裂都直接与震源的运动相联系，它们也可能是由于地震波造成的次生影响。特别是地表沉积层较厚的地区，坡地边缘、河岸和道路两旁常出现地裂缝，这往往是由于地形因素，在一侧没有依托的条件下晃动使表土松垮和崩裂。地震的晃动使表土下沉，浅层的地下水受挤压会沿地裂缝上升至地表，形成喷沙冒水现象。大地震能使局部地形改观，或隆起，或沉降。使城乡道路坼裂、铁轨扭曲、桥梁折断。在现代化城市中，由于地下管道破裂和电缆被切断造成停水、停电和通讯受阻。煤气、有毒气体和放射性物质泄漏可导致火灾和毒物、放射性污染等次生灾害。在山区，地震还能引起山崩和滑坡，常造成掩埋村镇的惨剧。崩塌的山石堵塞江河，在上游形成地震湖。1923年日本关东大地震时，神奈川县发生泥石流，顺山谷下滑，远达5千米。
[Outlined]
Seismic (earthquake) is the rapid vibration of the Earth's surface, also known as the earth will quake in ancient times. It just as windy, rain, lightning, landslides, volcanic eruptions, often occur on Earth is a natural phenomenon. It originated from the ground floor of a point, known as the focal point (focus). Vibration from the source reported, in the dissemination of the earth. On the ground from the nearest point source called the epicenter, it is the site of the earliest to accept vibration. Vibration of the land is the most intuitive earthquake, the most common performance. Coastal areas in the submarine or the strong earthquake, can cause huge waves, called tsunami. Is extremely frequent earthquakes, global in each of the earthquake about 500 million times, the community as a whole has a GREat impact.
[A] earthquake
Earthquake is the Earth's interior local media in the rapid breakdown of a seismic wave, which in a certain range ground vibration caused the phenomenon. The earthquake started in place as the source, the source is at the top of the ground known as the epicenter. The devastating earthquake ground vibration is known as the most strong earthquake, a seismic area that is often the epicenter of the region.
[Seismic phenomena:
When the earthquake occurred, the most basic phenomenon is the continuous ground vibration, is obviously the sloshing. Most people in the earthquake zone was shaking before the large, sometimes from top to bottom was the first beating. This is because the seismic waves from the ground came to the ground, vertical landing because of the first wave. S-wave and then have a big amplitude of the horizontal direction of the sloshing, is the main reason for the earthquake disaster. 1960 Chile earthquake, the biggest shaking lasted three minutes. First of all the disasters caused by the earthquake is the destruction of homes and structures, resulting in human and animal casualties, such as the 1976 Tangshan earthquake in China's Hebei Province, 70 percent to 80 percent of the buildings collapsed, and heavy casualties. Nature of earthquakes on the landscape have GREatly affected. The main consequences on the ground to a fault and crack. The surface earthquake fault often stretching several dozen to several hundred kilometers, often have more obvious mistakes of the vertical and horizontal distance from wrong, can reflect the structural changes in the source characteristics (see strong earthquake end, the San Francisco earthquake). However, not all the fault surface and the source directly linked to the campaign, they also may be due to seismic waves caused by secondary effects. In particular the surface sediment layer thick, slope edge of the road along the river banks and often occur in cracks, which often is due to topographic factors, not relying on the side of the swaying under the conditions of the topsoil Songkua and Benglie. The earthquake shaking the surface subsidence, the shallow groundwater will be squeezed along the cracks rose to the surface, take a sandblasting water phenomenon. Earthquake local topography can change, or uplift, or settlement. So that urban and rural roads chÈ cracked, twisted rail tracks, bridges broken. In modern cities, because of underground pipes and cables were cut off rupture caused by water, electricity and communications disruption. Gas, toxic gas leakage of radioactive material and can lead to fires and toxic, radioactive contamination, and other secondary disasters. In the mountains, earthquakes and landslides also caused landslides, burying villages and towns often caused the tragedy. The collapse of the rocks to plug rivers, forming the upper reaches of the earthquake in the lake. 1923 Great Kanto Earthquake in Japan, the Kanagawa Prefecture in mud-rock flows, down-valley, Yuanda 5 km.
Seismic (earthquake) is the rapid vibration of the Earth's surface, also known as the earth will quake in ancient times. It just as windy, rain, lightning, landslides, volcanic eruptions, often occur on Earth is a natural phenomenon. It originated from the ground floor of a point, known as the focal point (focus). Vibration from the source reported, in the dissemination of the earth. On the ground from the nearest point source called the epicenter, it is the site of the earliest to accept vibration. Vibration of the land is the most intuitive earthquake, the most common performance. Coastal areas in the submarine or the strong earthquake, can cause huge waves, called tsunami. Is extremely frequent earthquakes, global in each of the earthquake about 500 million times, the community as a whole has a GREat impact.
[A] earthquake
Earthquake is the Earth's interior local media in the rapid breakdown of a seismic wave, which in a certain range ground vibration caused the phenomenon. The earthquake started in place as the source, the source is at the top of the ground known as the epicenter. The devastating earthquake ground vibration is known as the most strong earthquake, a seismic area that is often the epicenter of the region.
[Seismic phenomena:
When the earthquake occurred, the most basic phenomenon is the continuous ground vibration, is obviously the sloshing. Most people in the earthquake zone was shaking before the large, sometimes from top to bottom was the first beating. This is because the seismic waves from the ground came to the ground, vertical landing because of the first wave. S-wave and then have a big amplitude of the horizontal direction of the sloshing, is the main reason for the earthquake disaster. 1960 Chile earthquake, the biggest shaking lasted three minutes. First of all the disasters caused by the earthquake is the destruction of homes and structures, resulting in human and animal casualties, such as the 1976 Tangshan earthquake in China's Hebei Province, 70 percent to 80 percent of the buildings collapsed, and heavy casualties. Nature of earthquakes on the landscape have GREatly affected. The main consequences on the ground to a fault and crack. The surface earthquake fault often stretching several dozen to several hundred kilometers, often have more obvious mistakes of the vertical and horizontal distance from wrong, can reflect the structural changes in the source characteristics (see strong earthquake end, the San Francisco earthquake). However, not all the fault surface and the source directly linked to the campaign, they also may be due to seismic waves caused by secondary effects. In particular the surface sediment layer thick, slope edge of the road along the river banks and often occur in cracks, which often is due to topographic factors, not relying on the side of the swaying under the conditions of the topsoil Songkua and Benglie. The earthquake shaking the surface subsidence, the shallow groundwater will be squeezed along the cracks rose to the surface, take a sandblasting water phenomenon. Earthquake local topography can change, or uplift, or settlement. So that urban and rural roads chÈ cracked, twisted rail tracks, bridges broken. In modern cities, because of underground pipes and cables were cut off rupture caused by water, electricity and communications disruption. Gas, toxic gas leakage of radioactive material and can lead to fires and toxic, radioactive contamination, and other secondary disasters. In the mountains, earthquakes and landslides also caused landslides, burying villages and towns often caused the tragedy. The collapse of the rocks to plug rivers, forming the upper reaches of the earthquake in the lake. 1923 Great Kanto Earthquake in Japan, the Kanagawa Prefecture in mud-rock flows, down-valley, Yuanda 5 km.
不感动
