甘肃青海部分地区流动地磁场时空分布特征

2021-05～2022-01青海地区陆续发生玛多M_S7.4、德令哈M_S5.8和门源M_S6.9地震。为深入探究上述地震的震磁关系，利用2019~2021年流动地磁场三分量矢量数据，探讨区域基本磁场与岩石圈磁场的时空分布特征及岩石圈磁场各分量年变与该区域中强地震的关系。研究发现，3期区域基本磁场的时空分布相似。震前最近一期岩石圈磁场资料显示，震中位置H矢量幅值弱变、方向偏转；震中位置与D、I、F、Z分量零值线的距离在200 km以内，玛多M_S7.4、门源M_S6.9地震震中位置与Z分量零值线的距离仅为5 km、20 km。此外，部分岩石圈磁场分量在2次强震前1 a呈现明显异常。

Temporal and Spatial Distribution Characteristics of Flowing Geomagnetic Field in Part of Qinghai,Gansu Province

From May 2021 to January 2022, Madoi M_S7.4, DelinghaM_S5.8 and MenyuanM_S6.9 earthquakes occurred in Qinghai. To further explore the relationship between earthquake and magnetism, we use the three component vector data of mobile geomagnetic field from 2019 to 2021 to explore the temporal and spatial distribution characteristics of regional basic magnetic field and lithospheric magnetic field. We further explore the relationship between the annual variation of each component of lithospheric magnetic field and moderately strong earthquakes in this region. We find that the temporal and spatial distribution of the basic magnetic field in the three periods is very similar. The latest lithospheric magnetic field data before the earthquake shows that the amplitude of H vector at the epicenter of moderate and strong earthquakes changed weakly and the direction turned. The epicenter location is within 200 km from the zero line of D, I, F and Z components. The epicenter distance of MadoiM_S7.4 and MenyuanM_S6.9 earthquakes are only 5 km and 20 km from the zero line of Z component. In addition, it is found that some lithospheric magnetic field components show obvious anomaly one year before two strong earthquakes.