2010—2017年甘川交界地震前震磁异常特征分析

Analysis of Seismic Magnetic Anomalies Characteristics before Earthquake in Gansu-Sichuan Junction area from 2010 to 2017

有效的识别孕震发震过程当中的物理变化是提升地震预报水平的必经之路,其物理变化的重现可以形成有效的预测指标。以甘川交界地区2010—2017年流动地磁观测资料和3次5级以上地震进行综合分析。结果表明:在川滇交界地区,6级以上地震前岩石圈磁场水平矢量方向整体趋势由南北两个方向向中间汇聚并形成弱化区域,地震发生在弱化区域边界;6级以下地震前岩石圈磁场水平矢量方向整体趋势由北至南(或由南至北)中间局部有弱化区域,地震也发生弱化区边界;无震则表现为在整体趋势由北至南(或由南至北)中间无弱化区域。

Effectively identifying the physical changes in the seis-mogenic process is the only way to improve the level of earthquake prediction,and the reappearance of its physical changes can form an effective predictive index.In this paper,a comprehensive analysis is carried out based on mobile geomagnetic observation data and three earthquakes with M>5 in the Gansu-Sichuan junction area from 2010 to 2017.The results show that:in the Sichuan-Yunnan border area,the overall trend of the horizontal vector direction of the lithosphere magnetic field before earthquakes with M>6 converges from the north and south directions to its middle region and forms a weakened area,and the earthquakes usually occurred at the boundary of the weakened area;before earthquakes with M<6,the overall trend of the horizontal vector direction of the lithospheric magnetic field from north to south(or from south to north)forms a weakened area in the middle region,and earthquakes also occur at the boundary of the weakened area;when there is no earthquake,there is no a weakened area within its overall trend.