基于亚失稳理论解释2010~2014年四川地区岩石圈磁场水平矢量异常变化特征

Variation Characteristics of Horizontal Vector Anomaly of LithosphericMagnetic Field in Sichuan from 2010 to 2014 Based on Meta-Instable Theory

梳理2010~2014年四川地区岩石圈磁场水平矢量异常空间变化特征,结果表明岩石圈磁场水平矢量年变化的弱变化区与中强地震具有良好的对应关系,震中均出现在弱变化区内或其边缘地带。结合亚失稳理论分析表明,研究区发生的10次中强地震中有9次与亚失稳理论各阶段均有较好的对应关系,其中宁蒗M_S5.7、康定M_S6.3等5次地震均发生在震前连续两期弱变化区域的重叠部位。因此,对于中强地震预报应多关注连续多期岩石圈磁场水平矢量弱变区的重叠部位。2011~2013年龙门山断裂带与鲜水河断裂带交汇区水平矢量异常明显,分析区域应力场与磁异常关系可知,芦山7.0级、康定6.3级地震的破裂区均受到来自东北方向应力的作用。

We analyze the spatial variation characteristics of horizontal vector anomaly of lithospheric magnetic field in Sichuan from 2010 to 2014.The results show that the weak variation area of horizontal vector of lithospheric magnetic field has a good correspondence with moderate-strong earthquakes,and the epicenters are all in the weak variation area or its edge zone.According to the meta-instable theory,9 of the 10 moderate-strong earthquakes occurred in the study area,which has a good correspondence with each stage of meta-instable theory.Among them,Ninglang M S5.7 and Kangding M S6.3 earthquakes all occurred at the overlap area of weak variation regions for two consecutive periods before the earthquake.Therefore,for the prediction of moderate-strong earthquakes,we should pay more attention to the overlap area of weak variation regions of horizontal vector of lithospheric magnetic field for consecutive multiple periods.From 2011 to 2013,the horizontal vector anomaly in the overlap area of Longmenshan fault zone and Xianshuihe fault zone are obvious.The analysis of the relationship between regional stress field and magnetic anomaly shows that the rupture areas of Lushan M S7.0 and Kangding M S6.3 earthquakes are affected by the stress from the northeast.