2015—2016年大华北地区岩石圈磁场变化及震前异常特征

Lithospheric Magnetic Field Variation and Pre-seismic Anomaly Characteristics in North China Area from 2015 to 2016

利用2015—2016年大华北地区260个测点流动地磁矢量资料,结合河北尚义4.0级和唐山4.0级地震,对获得的相邻期岩石圈磁场变化进行了分析。结果表明:尚义4.0级地震震中附近水平矢量H方向出现转向,同时处于磁偏角D变化的零值线上,磁倾角I和总强度F变化无明显的局部异常特征。唐山4.0级地震震中位于水平矢量H量级由北至南出现突然减小的变化,同时处于磁偏角D负值高梯级带边缘,也位于磁倾角I变化的正负值交界处,而总强度F却无明显的局部异常特征。

Using the mobile geomagnetism vectors of 260 observation points in North China from 2015 to 2016, and combing with the M4. 0 earthquake in Shangyi, Hebei as well as M4.0 earthquake in Tangshan, we analyzes the accessibly adjacent lithospheric magnetic field variation. The results indicate that the horizontal vector H changed direction near the M4. 0 earthquake of Shangyi, and it is on the zero value line of the variation of the magnetic declination D, while the variation of magnetic inclination I and the total intensity F have no evident lo- cal anomaly features. The M4. 0 earthquake epicenter in Tangshan is located in the horizontal vector H, where a variation of sudden diminution in it＇ s magnitude from south to north; meanwhile, it is on the edge of high gradi- ent zone of magnetic declination D＇s negative value, and is also located at the junction of positive and negative values of magnetic inclination rs variation. However, the total intensity F has no evident local anomaly features.