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一、引言早期的地震研究,人们通常习惯于一种思维模式,即地震事件是地壳应力不断强化最终导致局部失稳的结果。因而在前兆分析中,总是力图寻找与应力应变强化相关的各种信息。然而多年的预测实践表明,这种思路往往使得许多现象难以解释。例如在空间上,一些强震区的地壳应力并未达到人们估计的水平,甚至比一些地震平静区还要低。在时间上,地震通常不在许多前兆观测资料接近峰值时发生,而是出现在其后的相当一个时期,有时甚至难以找到足以反映加强阶段的前兆现象。地震孕育是否以单调加强的力学环境为
I. INTRODUCTION In the early earthquake research, people usually got used to a kind of thinking mode. That is, the earthquake event is the result of the continuous strengthening of the crustal stress and finally the local instability. Therefore, in the precursor analysis, always trying to find all kinds of information related to stress and strain hardening. However, many years of forecasting practice show that this kind of thinking often makes many phenomena difficult to explain. For example, in some areas, the crustal stress in some strong earthquake areas did not reach the level estimated by people, even lower than some earthquake-quiescent areas. In time, earthquakes usually do not occur when many precursory observations are near the peak, but rather for a considerable period thereafter, and sometimes it is sometimes difficult to find precursors enough to reflect the enhancement phase. Earthquake nurture monotonous strengthening of the mechanical environment for