GPS资料获取的静态库仑应力变化与余震分布的相关性分析

Static Coulomb Stress Variation Obtained by GPS Data and the Correlation with the 2008 Wenchuan Aftershock Distribution

本文以2008年汶川地震为例,利用震中附近GPS观测资料,选择断层破裂模型,计算汶川主震产生的静态库仑应力变化空间分布,并与JI模型、经验公式模型结果进行对比分析,初步探索GPS破裂模型下的静态库仑应力变化特征以及与余震的空间分布关系。结果表明,当使用最优断层面作为接收断层时,GPS模型的结果对后续余震空间分布具有较好的对应关系,90%的余震分布在应力增强区域;在龙门山断裂以走滑为主的北东段(北川—青川段),5级以上的强余震均分布在应力增强区;以龙门山断裂南西段作为接收断层的计算结果表明,芦山地震震中正好处于库仑应力的正值区,汶川地震的发生在一定程度上使得芦山地震提前发生。

In this paper,taking the 2008 Wenchuan Earthquake as an example,the fault slip model obtained by GPS observation data near the epicenter of the 2008 Wenchuan Earthquake,we calculate the static Coulomb stress changes and compare these results with that of the experience of sliding model and JI model results. We preliminarily explore the Coulomb GPS fault slip model under the stress characteristics and significance for the prediction of aftershock space distribution. Our results show that the static Coulomb GPS model can be used to obtain the stress distribution and subsequent aftershock distribution. And static Coulomb GPS model gives a good spatial relationship and 55% aftershocks in the stress reinforced area. From the spatial distribution,we also find that in the Longmenshan faults in the strike slip dominates activities of the North East（ Beichuan-Qingchuan）,the main shock triggered aftershocks. The region 67% aftershock distribute in the area of stress increasing that include the area of all of the above 5 aftershocks.