Analysis on Linear Polarization Pre-earthquake Anomalies of Geoelectric Field at Midu Seismic Station

In this paper, geoelectric field data recorded by Midu seismic station since 2007 are analyzed aiming at pre-earthquake vector directional changes of NS and EW direction before 4 M≥5.0 earthquakes occurred in Yunnan province and its surrounding areas using straight line fitting and linear correlation methods. The result shows that the polarization of geoelectric field gradually become linear during 3~6 months before earthquakes, which may be a kind of typical short-impending pre-earthquake anomaly and has significance for earthquake prediction.