基于低成本地磁场观测台阵的滇西南及邻区地震地磁Z分量异常分析OA

To improve earthquake forecasting efficiency in southwestern Yunnan,Tianjin Earthquake Agency,Tianjin University,and Yunnan Earthquake Agency have deployed a low-cost geomagnetic field observation array in Lincang City,achieving the intensive observation of regional geomagnetic field.Based on the observation data of low-cost geomagnetic field observation array in Lincang City,this paper analyzed the variation characteristics of geomagnetic Z-component before the significant earthquakes in southwest Yunnan and its adjacent areas from Au-gust 2023 to April 2025 by using the load-unload response ratio method and correlation analysis method.The re-sults show that under the premise of eliminating instrument failure,environmental interference,solar activity and other influencing factors,6 of the 10 earthquakes with M≥4.0 within 500 km from the geomagnetic field observation station have abnormal Z-component load and unload response ratio in 2-23 days before the earthquake,which ex-ceeds the threshold.The daily variation amplitude of multiple stations decreases to varying degrees,and the daily variation trend is"flattened",and usually lasts for 2-3 days.The daily variation correlation of Z-component in 4-6 days before two M3.0 small earthquakes within 20 km from the geomagnetic field observation station is lower than the threshold value,along with trend inversions at individual stations.The extraction of Z-component geomagnetic anomalies associated with seismic activity in southwestern Yunnan and its adjacent areas proves that low-cost geo-magnetic field observation can provide reference for short-term and imminent earthquake forecasting in a certain ar-ea.