龙陵大震震型及有关问题讨论

DISCUSSION ON THE SEISMIC TYPE OF THE LONGLING EARTHQUAKE AND SOME PROBLEMS CONCERNED

本文根据1976年龙陵大震三次主震由南向北的迁移特征以及3次主震及其强余震活动所反映的震源时空分区特征认为,该次大震属续发性大震型,即三次主震分别位于不同的震源区,但首尾相接,且各自有前震和余震。用立交模式和深部剪切蠕滑断层对龙陵大震发生在完整的花岗岩体内作了解释。用介质相对完整、区域压力大解释了主震发生时形成复式震源,以及余震相对发育的特征。对于复式震源提出了用各震源断层长度累计总和求震级的方法。

According to the migration characteristics of three main shocks of the Long ling earthquake from the south to the north and the temporal-spacial zoning characteristics of sources based on the seismic activities of three main shocks and strong after shocks, the authors consider that the seismic type of the Longling earthquake is belong to a type of great ensuing earthquakes, i.e. the three main shocks are located on different sources respectively which link each other from the beginning and the end, and the three source regions have its fore-and after-shocks respectively. The reason why the Longling earthquake occurred in complete granite has been interpreted by stereo model and shear creep fault in deep, It has also been explained, forming multiple source when the main shock occurred and developping aftershocks because of the relative complete medium and the strong regional compress stress. A method to estimate magnitude of multiple source summing the length of each source fault has been advanced.