论文部分内容阅读
地震是一种自然现象.全球一年大约发生大小地震500万次,人们能感觉到的约5万次,其中1000次能造成轻微的破坏.大地震每年约10次,如发生在人烟稠密地区将造成生命财产的严重损失.所幸这种地震并不多,比1975年海城和1976年唐山地震破坏力更大的地震,每年全球仅发生约1次.利用地震时地震波在地下传播的情况,可以了解地球内部的结构,但一般人们更为关心的则是地震能否预报.预报地震首先要观测研究地震,弄清地震是怎样发生的.一般认为,绝大多数地震是由于地下的岩石受到挤压造成断裂错动所引起的,以内因为主,潮汐力等外因只能起触发作用.当地震发生时,所产生的地震波从震源向四面八方传播,地震台站用灵敏的地震仪把地震波记录下来.一般用3个地震台站所记录的地震波到时,或用一个地震台站所记录的纵波和横波到时,就可算出震中的位置;再根据震波的振幅以及震中到地震台站的距离,便能估算出地震的震级(即地震的大小).地震观测的发展趋势,主要是建立固定地震台站、加宽测震仪器的频带和建立流动台站等3个方面.最初人们是把单个的地震台建设在远离城市的安静地区,有
Earthquakes are a natural phenomenon: Earthquakes amount to about 5 million times a year around the world, about 50,000 times people can feel it, of which 1000 can cause minor damage. The earthquakes occur about 10 times a year, as occurs in densely populated areas Will result in serious loss of life and property Fortunately, this earthquake is not much, more than in 1974 and Haicheng in 1976 Tangshan Earthquake more destructive earthquakes occurred once a year in the world only about the use of earthquakes in the earthquake propagation in the ground Can understand the structure of the Earth’s interior, but generally people are more concerned about whether the earthquake prediction.Pre-earthquake prediction and observation of the earthquake first to understand how the earthquake is generally believed that the vast majority of earthquakes is due to underground rock When the earthquakes occur, the seismic waves generated from the earthquakes propagate from all sources in all directions. The seismic stations use the sensitive seismometers to send the seismic waves Recorded .Generally with three seismic stations recorded seismic waves arrived, or with a seismic station records the longitudinal and shear waves to the time, you can calculate the location of the epicenter; then according to the earthquake The amplitude of the earthquake and the distance from the epicenter to the seismic station can estimate the magnitude of the earthquake (ie, the magnitude of the earthquake). The trends in seismic observation are mainly to establish a fixed seismic station, broaden the frequency band of the seismic instrument, and to establish a mobile station Station, etc. Initially, people built a single seismic station in a quiet area away from the city. There are