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1950年至1978年间,克里特岛(Crete)南部的地震活动频次在空间和时间上都是稳定的。但是在希腊海沟西部,直到1962年,其活动频次仍与克里特岛南部一样。随后,它减少了80%。现在我们认为,这种异常已成为在未来的十年内要发生大地震的前兆。我们研究了已发生的20个大于6.0级地震,其结果表明,在主震到来之前的几年中,小震的频次约降低50%。例如:夏威夷7.2级地震之前几年中的情况就是如此。而且,在那里的地震活动的减少还伴随着另外两种前兆现象:地壳应力的松驰和地震波速的改变。因此,我
Between 1950 and 1978, the frequency of seismic activity in the south of Crete was stable both spatially and temporally. However, in the western part of the Greek trench, it was not until 1962 that its frequency of activity remained the same as in southern Crete. Then it was reduced by 80%. Now we think that this anomaly has become a precursor to a major earthquake in the coming decade. We studied 20 earthquakes larger than 6.0 that occurred, and the results showed that the frequency of small earthquakes decreased by about 50% in the years prior to the main shock. For example: This is the case in the years prior to the magnitude 7.2 Hawaii earthquake. Moreover, the reduction in seismic activity there is accompanied by two more precursory phenomena: relaxation of crustal stress and changes in seismic velocity. so I