Abstract: In about three years the observation of microearthquakes has been made by setting up three short-distance station networks,separately one of which is along the river, others at Yanguan and along the fault belt in Xiannu mountain,near the place where the dam of the Yangtze Gorge will be made.We have basically studied the features and levels of seismic activity.The seismic activity has been herein presented in order to evaluate the possibility of induced earthquake in the Three Gorge reservoir which will be made in several years.

Key words: Microseismic observation, Nature earthquake, Rock brust, Three Gorge area

摘要： 通过长江三峡库首区沿江段、盐关和仙女山断裂带3个小孔径台网近3年的地震强化观测,发现该地区同时存在着天然地震和矿山地震。其中黄陵背斜轴部结晶花岗岩体内没有观测到极微震活动；西缘秭归香溪至龙马溪一带存在着百余次微震,最高震级为M_L2.5级盐关地震,与这一带的矿山开采有关；东缘宜昌石门附近也分布有数次微震；在黄陵背斜外围区域分布着若干3～4级(M_L)弱震。这些地震的发生基本上反映了该地区的弱活动构造格局。

关键词: 微震观测, 天然地震, 岩爆, 三峡地区