诱发前震图象与1995年1月17日日本阪神大地震

PATTERNS OF INDUCED FORESHOCKS AND THE JAN. 17,1995 OSAKA-KOBE EARTHQUAKE, JAPAN

地震引起的应力场扰动随距离不断衰减，远程触发很难发生，只有极不稳定状态的断层才有这种可能。利用这一特点，可以预报下次地震的位置，为实施减灾措施和捕捉短临前兆提供机会。所以，紧随大地震之后发生的“诱发前震”就具有了特殊的前兆意义。统计表明，大地震（Ａ事件）可能触发远处临界失稳断层发生前兆地震（Ｆ事件），在Ｆ事件附近发生下次大震（Ｂ事件）的概率比自然概率高十几倍到几十倍。这一结论被从中国大陆、全球主要板块边界及日本列岛发现的众多ＡＦＢ图象所证实。对其发生的可能的物理机制在文末进行了讨论。

The stress field disturbance caused by an earthquake would attenuate with the distance,so long distance triggering hardly occur. It would appear only on the fault in extremely un stable state. This character can be used to predict the location of next earthquake, and it provides a chance for carrying out the measures of disaster mitigation and seizing the impend ing precursors. So the 'long distance aftershock' closely following a large earthquake has special precursory significance. The statistics shown that a large earthquake (A event)would trigger precursory earthquakes (F event)at a long distance on the unstable fault. Near the location of the F event, the probability of next large earthquake (B event) is ten-odd or tens times higher than the natural probability. This conclusion had been proved by the AFB images of China mainland, the boundaries of main plates and the Japan Islands. The proba ble physical mechanism of long distance trigger are discussed in the end of the paper.