Abstract:We study the temporal and spatial evolution characteristics of the low point of the daily variation of the geomagnetic vertical component before the Songyuan M5.7 earthquake. The results show that: 1) when the isoline of the low point time 0 h after the longitude effect is removed, the epicenter of the Songyuan M5.7 earthquake is located on the boundary of April 13 and near the boundary of April 24, respectively; 2) during the abnormal day(the geomagnetic vertical component day of the mainland of China), the daily deformation patterns in the region with positive and negative low point time after longitude effect removal are mainly W-shaped and V-shaped respectively; 3) during the two abnormal days of April 13 and April 24, there are high gradient zones with low point time after longitude effect removal in mainland of China, and the epicenter of Songyuan M5.7 earthquake is located at the edge of high gradient zone on April 13, and the east side of high gradient zone on April 24 respectively.
DAI Yong,GAO Lixin,YAO Li et al. Low-Point Temporal and Spatial Evolution Characteristics of Geomagnetic Vertical Component Diurnal Variation before the Songyuan M5.7 Earthquake[J]. jgg, 2020, 40(6): 601-607.