基于PALM自动检测方法的三峡库区微震活动研究

Research on Microseismic Activity in Three Gorges Reservoir Based on PALM Automatic Detection Method

选用三峡工程水库诱发地震监测系统在库首区布置的24个台站采集的2016~2018年数据,利用PALM微震检测定位方法对三峡库区进行微震检测定位分析。共检测到12 814次地震动事件,约为同时段三峡地震台网目录的4倍,完备震级从ML0.8下降至ML0.3,表明PALM方法可提高台网监测能力。基于构建的更完善的极微震-微震目录,分析库区地震活动空间分布特征。结果表明,巴东地区震源深度较浅,多在5 km以内,主要与岩溶、煤矿塌陷和浅表卸荷等非构造因素有关;秭归地区震源深度较深,多在5~15 km,主要与库区九畹溪和仙女山两条断裂活动有关。

We use the data of 24 stations in the reservoir head area collected by Three Gorges reservoir induced earthquake monitoring system from 2016 to 2018,and use PALM method to analyze microseismic detection and positioning in Three Gorges reservoir area.A total of 12814 seismic events are detected,which is about 4 times the number of seismic events in Three Gorges seismic network directory during the same period.The complete magnitude decreased from M L0.8 to M L0.3,proving that the PALM method is an effective way to improve the detection ability of seismic network.Based on the construction of a more comprehensive microseismic catalog,we delineate the spatial distribution characteristics of seismic activity in Three Gorges reservoir area.The results show that the focal depth in Badong area is relatively shallow,mostly within 5 km,mainly related to non-structural factors such as karst,coal mine collapse,and shallow unloading.The focal depth in Zigui area is relatively deep,mostly within 5 to 15 km,mainly related to the Jiuwanxi and Xiannüshan faults in the reservoir area.