2003年6、7月西昌二次4.8级地震的预测与分析

2003年6月17日和7月10日,先后在四川省西昌市和西昌-昭觉间发生2次ML4 8级强有感地震.对于这2次地震,我们曾作了较好的中期和短期预测.但是对于6月17日发生的第一次ML4 8级地震,未能做出临震预测;对于第二次地震,则在7月1日向上级填报的周会商表中作了明确的临震预测,7月10日,在西昌-昭觉间发生了ML4.8级地震.根据西昌地震遥测台网各子台的P波初动求解震源机制,结合地震所处的地质构造以及现场烈度考察圈定出的结果分析,认为这二次地震是由安宁河断裂带、则木河断裂、凉山断裂所围成的凉山小菱形块体活动的结果.

Analysis and prediction on two Xichang earthquakes with M4.8 in June and July 2004

Two earthquakes with M_L4.8 occurred on 17 June and 10 July 2003 separately in Xichang.Before these earthquakes,the intermediate-and short-term earthquake predictions were made but the imminent earthquake prediction for the first event was not made.According to the focal mechanism solution with P waves first movement and the seismological and geological structures (along) Anninghe,Zemuhe and Liangshan faults,we think that the two earthquakes result from the activities of these faults.