汶川8.0级地震前地磁低点位移与内外源S_q等效电流体系关系的研究  

Minimum Point Shift of the Geomagnetic Vertical Component in Diurnal Variation and the Internal-external Equivalent Current System S_q before the 2008 Wenchuan M_S8.0 Earthquake

作　　者：袁桂平[1] 张学民[1] 吴迎燕[1] 赵旭东[2] 

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]中国地震局地球物理研究所,北京100081

出　　处：《地震》2015年第3期102-112,共11页Earthquake

基　　金：国家高技术研究发展计划(2012AA121004)

摘　　要：本文利用球谐分析方法构建内外源Sq等效电流体系反演模型,对2008年汶川8.0级地震前的4月24日及5月9日两次地磁低点位移日前后共10日的内外源Sq等效电流体系进行逐日反演,并结合Dst磁暴指数分析研究地磁低点位移和电流体系之间的关系。研究发现:低点位移发生当日内外源等效电流体系南北半球电流涡中心强度都有减小的趋势,且内源场减小的幅度更大。低点位移发生日内源等效电流体系电流涡中心可能会发生纬向偏移现象。We built an inversion model for separating internal and external equivalent current system Sq by the spherical harmonic analysis method, which was used to inverse daily for Sq 10 days around two minimum shift dates of April 24 and May 9, 2008 before the Wenchuan 8.0 earthquake. Combining with the index of geomagnetic storms （Dst）, we analyzed the relationship between minimum point shift of the geomagnetic vertical compo- nent in diurnal variation and current system. We found that, on the days of minimum point shift of the geomagnetic vertical component in diurnal variation, the strength on the center of vortex has a tendency to decrease in internal and external equivalent current sys- tem for both the north and the south hemisphere, and the size of the internal field de- creased bigger. Further, the center of vortex shifted on the days of minimum point shift of vertical component geomagnetic in diurnal variation.

关 键 词：地磁低点位移 球谐分析 Sq等效电流体系 汶川8.0级地震 

分 类 号：P315.7[天文地球—地震学]