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近年来,除了依靠对地震活动本身的定量描述来判断地震活动的发展趋势以外,地震本身还提供了下述两方面的资料作为可能的前兆:一是利用地震波传播速度在震前的变化来预报地震;其次是利用地震波传播时在介质中的衰减特征来预报地震。两种方法的物理基础均为利用地震波在地球内部旅行时对地球介质进行采样所给出的讯息来监测地震前后介质的变化。两种方法经历着不同的道路。回想起来,当找到用波速预报地震的震例时的那一瞬间,地震学家受到何等的鼓舞。当时的地震界对地震预报曾是十分乐观的,似乎是确定性地而不是概率性地预报地震的时刻已经到来。不久,怀疑和否定的意见即接踵而至。不少人指出精确的测量波速反而表明震前波速并未出现明显变化,而蓝山湖震例中所
In recent years, in addition to relying on the quantitative description of seismic activity itself to determine the trend of seismic activity, the earthquake itself also provides the following two sources as a possible precursor: one is the use of seismic wave propagation velocity changes before the earthquake to predict Earthquakes; and secondly, the earthquakes are predicted using the attenuation characteristics of the seismic waves propagating in the medium. The physical basis of both approaches is to monitor the change of medium before and after the earthquake by using the information given by sampling the Earth’s medium when the seismic wave travels inside the Earth. Both methods go through different paths. In retrospect, seismologists were encouraged by the moment when they found the earthquake that predicted the earthquake with wave speed. The seismological community at the time was once a very optimistic earthquake prediction, and it seems that the time has come to predict the earthquake deterministically rather than probabilistically. Soon, doubts and negative comments ensued. Many people pointed out that accurate measurement of wave velocity but showed no significant changes in wave velocity before the earthquake, and Lushan Lake earthquake cases