地磁低点位移异常：岷县-漳县M6.6地震可能的震前反映

选取天水地磁台（TSY）和兰州地磁台(LZH)2011~2013年、乾陵地磁台(QIX)）2012~2013年以及成都地磁台(CDP)观测资料，基于小波多尺度分解，提取地磁垂直向日变的最低点时刻，在时间域展现低点位移变化特征。结果表明，从2013-05开始，天水台地磁日变低点时刻表现为持续上升（低点时刻逐渐滞后），2013-07初达到峰值。岷县-漳县地震(2013-07-22 M6.6)发震时间处在低点位移下降段，而其他台站低点位移在震前未出现异常变化。结合其他文献认为，天水地磁低点位移异常可能是这一地震孕育和发生过程在地磁场的反映。

Abnormity of Geomagnitics Low-Point Shift: A Possible Seismogenic Reflection of the Minxian-Zhangxian M6.6 Earthquake

In this paper,we use observation data for Tianshui geomagnetic station(TSY), Lanzhou geomagnetic station (LZH), Qianling geomagnetic station(QIX), and Chengdu geomagnetic station(CDP), based on multi-scale wavelet decomposition, extraction of time of low-point on vertical compenent,and variation process of low-point shift on time. The results show that the low-point shift continues to lag the vertical compenent on Tianshui geomagnetic station (TSY) from May to July 2013.The range of variation lies beyond the normal state, but other stations do not present this abnormal phenomenon. This process shows localized features at Tianshui station; the Minxian-Zhangxian 2013-07-22 M6.6 earthquake occurrence is on down-point time of low-point shift peak, showing the correlation between the anomaly and the earthquake. This may be a reflection of seismogenics in the geomagnetic field. These results have an important reference value in the study of the seismogenic process, mechanism dynamics process of geomagnetic low point shift, and exploration on earthquake prediction.