应用强震应力降和视应力进行震后趋势快速判定的可能性

Possibility of Earlier Judgement on Seismic Tendency after Strong Earthquake Based on Apparent Stress and Stress Drop

收集整理了中国大陆107次M≥5.0地震的震型、发震断层性质等资料,分不同发震断层性质和不同震型两种情况,比较了不同地震视应力的大小关系。结果显示,地震视应力的高低和发震断层性质有关,也和地震类型有关。走滑型地震的视应力高于非走滑型地震的视应力,走滑断层中孤立型地震视应力低于多震型地震视应力。非走滑型地震情况则复杂得多,既有视应力很高的孤立型地震,也有视应力很低的多震型地震。为了进一步探索利用强震本身的信息快速判定震型的方法,还通过视应力计算了18例强震的静态应力降与动态应力降之比值Y,得到当Y>0.2时,强震可能为孤立型或近孤立型的主震—余震型地震,当Y<0.2时,强震可能为多震型或强余震丰富的主震—余震型地震的认识。

In this paper, 107 earthquakes of M≥5.0 are collected that occurred in China's Mainland. Based on different types of data of these events including earthquake sequences, stress drop and seismic moment, we discussed the intensity of apparent stresses of different earthquakes classified into two classes according to earthquake fault characteristics and earthquake types. The results show that the intensity of earthquake apparent stress is related to the earthquake fault characteristic and earthquake type. The intensity of apparent stress of single strike-slip earthquake is higher than that of non-strike-slip earthquake. Among strike-slip faults, intensity of apparent stress of single-shock type earthquake is lower than that of multiple-shock type earthquake. For non-strike-slip type earthquake, the situation is more complicated, and there are single-shock earthquake of high apparent stress, and also multiple-shock earthquake of low apparent stress. In order to rapidly judge earthquake type using the information of strong earthquake itself, we calculated Y, the ratio of static stress drop to dynamic stress drop, of 19 strong earthquakes. Finally it is found that when Y is higher than 0.2, the strong earthquake may be single-shock earthquake or main shock-aftershock type earthquake with less aftershocks, and when Y is lower than 0.2, the strong earthquake may be multiple-shock earthquakes or main shock-aftershock type earthquake with abundant strong aftershocks.