河北及周边地区岩石圈磁场变化及震前异常特征

利用2019年度大华北秋季复测156个测点的流动地磁矢量资料，获得河北及周边地区岩石圈磁场半年变化图，分析归纳河北及周边地区岩石圈磁场的总体变化特征，并研究测区内2019年12月3日河北怀安M_S3.4地震和2019年12月5日河北丰南M_S4.5地震前岩石圈磁场局部变化和异常特征。结果表明：丰南M_S4.5地震发生在H矢量的转向区，总强度F负异常的高值区，D要素负异常的高梯度带和Z值变化的高值区；怀安M_S3.4地震则发生在H矢量幅值弱化且转向区，D要素零值线附近的正值区和Z值变化的低值区。

Variation and pre-seismic anomaly characteristics of the lithosphericmagnetic field in Hebei Province and its surrounding areas

In this paper, the semi annual variation of the lithospheric magnetic field in Hebei and its surrounding areas was obtained by using the data of mobile geomagnetic vector from 156 observation points of North China in autumn 2019, and the overall variation characteristics of lithospheric magnetic field in the study area were analyzed and summarized. Furthermore, the local variation and anomaly characteristics of lithospheric magnetic field before the Huai''an, Hebei M_S3.4 earthquake on December 3, 2019 and the Fengnan, Hebei M_S4.5 earthquake on December 5, 2019 were studied. The results showed that the epicenter of Fengnan M_S4.5 earthquake was located in the turning area of vector H, the high value area of negative anomaly of total intensity F, the high gradient zone of negative anomaly of element D and the high value area of Z value. The Huai''an M_S3.4 earthquake occurred in the area where the amplitude of vector H weakened and turned, the positive area near the zero value line of element D and the low value area where the Z value changed.