2013年3月3日洱源M_S5.5地震前地磁谐波振幅比异常研究  

Variation of the geomagnetic harmonic wave amplitude ratio before the M_S5.5 Eryuan earthquake in 2013

作　　者：李琪[1] 袁伊人 杨星[2] 蔡绍平[2] 孙维怀[3] 

机构地区：[1]中国地震局地球物理研究所,中国北京100081 [2]云南省地震局,中国昆明650224 [3]云南省地震局通海地震台,中国通海652700

出　　处：《地震学报》2016年第1期122-129,158,共8页Acta Seismologica Sinica

基　　金：地震行业科研专项(200708033)资助

摘　　要：本文首先使用滇西北地磁台阵8个测点2012年6月1日—2013年5月31日记录的短周期地磁数据,计算得到各测点的谐波振幅比时间序列变化曲线.该曲线显示:各测点的谐波振幅比YZHy和YHD在2013年3月3日普洱MS5.5地震前均呈显著高值,发震前则刚好是由高转低再上升的一个转折点;而谐波振幅比YZHx没有出现类似的异常变化.其次通过对台阵区地下电导率结构的定性分析,对该计算结果予以解释.对于地磁短周期垂直分量反相现象和威斯矢量分布的分析结果表明,地下存在着近似南北走向的电导率异常带.由于台阵区域YZHy和YHD的异常变化代表南北向地下电导率变化和地下电导率不均匀,因此谐波振幅比的变化与电导率异常带的分布一致,表明谐波振幅比的变化与地下电性结构密切相关.Based on the 1 second sampling geomagnetic data derived from the eight stations of geomagnetic array in Yunnan Province from June 1, 2012 to May 31, 2013, the temporal variations of the geomagnetic harmonic wave amplitude ratios were analyzed. It was found that both the geomagnetic har- monic wave amplitude ratios YzHy and YHD were enhanced just before the MsS. 5 Eryuan earthquake on 3 March 2013, but no similar variation appeared for the ratio YzHx. In order to explain the result, both the temporal evolution of origi-nal vertical components （Z） and the distribution of Weiss vectors were ana- lyzed, and it was found that there was an NS-oriented high conductivity layer on the underground. Considering that the ratios YzH,, YHD and YzHx are related with the variation of NS-oriented conductivity, the heterogeneity of under- ground electrical structure and the variation of EW-oriented conductivity, respec- tively, it was deduced that the variation of the geomagnetic harmonic wave amplitude ratios was closely related to the underground electrical structure.

关 键 词：谐波振幅比 地下电导率结构 地磁台阵 震例分析 

分 类 号：P315.721[天文地球—地震学]