基于案例分析的库仑应力变化触发地震机理探索

Exploration of the Mechanism of Earthquake Triggering by Coulomb Stress Change Based on a Case Analysis

摘要:

在许多地震触发研究案例中，不少学者都利用大地震造成的库仑应力变化研讨其对后续地震的影响，但众多结果中存在的共同规律尚未得到很好的统计与归纳。基于库仑应力变化理论，通过统计多个地震序列与典型事件中库仑应力研究结果，分别从震级、触发距离、触发地震库仑应力变化（ΔCFS）以及触发时间4个方面进行分析。结果表明，静态库仑应力的最优影响范围在5~50 km间，触发地震的应力条件多在0.01~0.4 MPa，触发地震震级与距离和主震震级无明显对应关系；动态触发的作用范围在100~2500 km间，主震震级通常较高，触发地震的震级都小于主震震级，在几个典型远程触发的事件分析中，主震震级与可触发距离呈正相关，但触发次数与其他所分析因素均无关；震后应力转移的三种机制，从理论上合理地解释了长时间尺度延迟触发的现象，但精确计算应力转移的量值可能对库仑应力变化与触发地震之间关系的更合理解释有推动作用，需引起关注。

Abstract:

In many cases of seismic triggering, several scholars have studied the effects of Coulomb stress changes caused by large earthquakes on subsequent earthquakes. In this study, based on the Coulomb stress change theory and through the statistics of the Coulomb stress results in the study of some earthquake sequences and typical events, we carried out the analysis from four aspects:magnitude, triggering distance, Coulomb stress change, and triggering time. The results show that the optimal influence range of static Coulomb stress is 5-50 km, and the stress condition of triggering earthquakes is usually 0.01-0.4 MPa; however, the triggering magnitude has no clear correlation with the distance and the magnitude of the main shock. The range of dynamic triggering is mostly 100-2 500 km; the magnitude of the main shock is always high, and the magnitudes of the triggered earthquakes are all smaller than that of the main shock. The magnitude of the main earthquake is positively correlated with the triggering distance, but the triggering times are independent of other factors in the analysis of several typical remote triggering events. The phenomenon of delay triggering in a long-term scale is reasonably explained by three mechanisms of post-earthquake stress transfer, but the accurate calculation of stress transfer may have a positive effect on the reasonable interpretation of the relationship between Coulomb stress change and earthquake triggering.