2021年科尔沁MS4.7地震震前地磁反相位感应电流特征分析OA

Taking the 2021 Horqin MS4.7 earthquake as a case study,this paper uses the Biot-Savart law and the Monte-Carlo method,and employs the abnormal amplitude of the anti-phase geomagnetic vertical component at observation stations to invert and locate the information of these earthquake-in-duced currents.It reveals the temporal and spatial evolution characteristics of the induced currents re-lated to the pre-earthquake geomagnetic anti-phase anomalies,as well as their correlations and influ-ences with seismogenic structures and nearby/far-field earthquakes in the surrounding areas.Spatial distribution of induced currents:1)The distribution trend of the peak value of induced currents is sim-ilar to the nature of the seismogenic fault.2)Conjugate-shaped induced currents appear before the earthquake.Temporal sequence analysis of induced current depth:1)The depth of induced currents during the earthquake occurrence period is very close to the focal depth.2)As the earthquake approa-ches in time,the first-order difference of the shallowest depth of induced currents shows a convergent trend.3)Surrounding earthquake events can cause the phenomenon of"shrinking before the earthquake and increasing after the earthquake"in the maximum depth of induced currents.This study represents a new attempt in the application of the electromagnetic discipline to the location of earth-quake precursor anomalies,and provides new ideas for the short-term and imminent earthquake pre-diction methods based on electromagnetic anomalies.