一、引言西昌市是凉山彝族自治州的州府,座落在一第四纪断陷盆地中。盆地呈北北西向展布,长约15公里,宽5—6公里。盆地的中、南部为邛海湖所占据,积水面积31平方公里,水深最大可达30余米,为四川第二大湖。这里地处北北西向则木河断裂与近南北向安宁河断裂的汇合部位附近, I. Introduction Xichang is the state capital of Liangshan Yi Autonomous Prefecture, located in a Quaternary rift basin. Basin was north-west distribution, about 15 km, 5-6 km wide. The middle and south of the basin are occupied by Qionghai Lake, with a water area of ​​31 square kilometers and maximum water depth of 30 meters, making it the second largest lake in Sichuan. Here lies the vicinity of the confluence of the northwestern and western Zemuhe faults and the An-Ning An-hai fault near the north-