震源联合定位方法在三峡库首区地震定位中的应用

Joint Hypocenter Determination for Earthquakes in the Head Region of Three Gorges Reservoir

利用三峡台网2001年1月1日至2011年9月9日的到时地震波形资料,采用震源联合定位方法,对三峡库首区7 011次地震重新定位,得到了不同蓄水阶段的台站校正值。结果显示:①地震主要分布在长江沿岸,并集中于郭家坝—屈原镇、泄滩、巴东—巫山一带;②三峡库首区存在地震波速横向不均匀性,速度分布与地质构造、蓄水等因素密切相关;③蓄水前地震波速分布情况主要受地质构造影响,而蓄水阶段三峡库首区的地震波速分布情况除受地质构造影响外,还受库区渗水影响。该方法在三峡库首区地震定位中取得了很好的应用效果。

According to the data of earthquake arrival time obtaihed from the Three Gorges network from 2001 toSeptember 9, 2011, we employed the method of joint hypocenter determination to relocate 7011 earthquakes in the head region of Three Gorges area and obtained the station correction values in different stages of water storage. The results show that： 1 ） earthquakes mainly occurred along the Yangtze River and concentrated at Guojiaba- Quyuanzhen, Xietan, and Badong-Wushan areas; 2） the lateral velocity in the head region of Three Gorges reser- voir is inhomogeneous, and the velocity distribution is closely related with the geological structure and the condition of water storage ; 3 ） the velocity structure in the head region of Three Gorges reservoir is mainly affected by geolog- ical structure before water storage, and is affected by geological structure and reservoir seepage during storage. This method has good effect for seismic location in the head area of the Three Gorges reservoir.