摘要
简要介绍了2003年6月三峡水库蓄水以来整个库区地震活动概况,探讨了三峡库区主要断层的渗透结构特征,详细论述了三峡坝前水位变化与库区不同库段、不同地质背景、不同成因水库地震活动的对应关系。三峡库区地震活动统计结果显示,高水位情况下若水位变幅剧烈,容易诱发地震,随着水位的上涨,地震震中呈现向长江及主要支流库岸汇聚的现象,水库地震主要受江水涨落而非构造所控制。除此之外,由于库区不同库段渗透结构差异,随着水位的上涨,库区M2.0级以上地震早期在高桥断裂一带(靠西)活动较多,后期仙女山、九畹溪两断裂(靠东)一带有一定地震活动。
We briefly present the general situations of earthquake activity in Three Gorges Reservoir area since its impoundment in June,2003,discuss the permeability structure of the main fault and the relationships between the water level variation in the front of dam and the earthquake activity under the conditions of different geological backgrounds in different areas and various causes.The statistical results of earthquake activity in the reservoir area show that it is easy to induce earthquake in case of strong variation of water level under the condition of high level and the epicenter of micro-earthquake in reservoir area moves towards the reservoir banks of the Yangtze River and its main tributaries with the rise of water level.It can be seen that the reservoir earthquake is influenced by the river level fluctuation rather than the structure.Besides,due to the differences of permeability structure in different reservoir areas,the earthquakes above M 2.0 occurred more in the Gaoqiao Fault area in early period,later in the Xiannvshan and Jiuwanxi Fault areas.
引文
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