虎跳峡工程近场区断裂活动性与地震危险研究

Research on fracture activity and seismic danger in nearby region of Hutiaoxia hydroproject

拟建的虎跳峡水利枢纽工程是金沙江石鼓—宜宾河段的关键性枢纽工程 ,地处我国西南部地区著名的中甸—大理强震频繁带 ,近场区主要断裂构造有 5组。通过地形地貌调查、断裂物质测年、地震活动监测等手段 ,认为其中 13条断裂带自第四纪以来有过明显的活动 ,并对其中 9条断裂的活动特征及地震危险性进行了评价。各主要断裂地震危险性分析表明 ,工程地区东部主要断裂带具备发生 7级以上地震的构造条件 ,西部主要断裂带具有发生 5～

Hutiaoxia hydropower project to be constructed is a key one on the Shigu Yibin stretch of the Jinsha river and is located in a well known frequent strong earthquake zone from Zhongdian to Dali in South west China. There are five main fracture structures in the near field zone. Through topographic and morphologic investigation, dating of fracture materials and monitoring of earthquake activities, etc., it is held that there exist 13 fracture zones having obvious signs of activities since the Quaternary period. The activity characteristics and seismic risks of 9 fractures from these fractures have been evaluated. The seismic risk analyses of main fractures show that the main fracture zones in the east part of the project area are provided with structural conditions for occurrence of earthquakes of over magnitude 7, and those in the west part of the project area have risks for medium strong earthquakes of magnitude 5～6 to occur.