【摘要】 广东省新丰江水库蓄水后地震活动性有很大增高,大部分地震发生在大坝附近的深水峡谷区,形成一条北西方向的密集带,震源深度极浅,随后,在蓄水后约二年半于1962年3月19日发生了6.1级强地震。 根据水准测量与地震波波谱资料的分析确定了主震的断层参数;用P波初动振幅确定了主震前后18个月内150次小地震的断层面解,用平滑P波初动图案求得了2000余次小地震的发震应力方向;计算了水库荷载在库基岩体中产生的位移场和应力场;分析了主震及其几个大余震前的地震纵波与横波的速度比变化情况。 结合地震活动性和地质背景初步讨论了新丰江水库地震的诱发机制,认为:水的渗透作用是诱发这次地震的主要原因。更多还原

【Abstract】 After the filling up of the Xinfengjiang Reservoir, Guangdong Province, seismi-eity was greatly increased. The majority of earthquakes occurred in the deep water gorge close to the dam, concentrated within a north-west belt. They are of shallow focal depths. A strong earthquake with magnitude 6.1 took place on March 19, 1962, about two and a half years since the impounding of the reservoir.According to the results of analysis of data from geodetic leveling and the spectra of seismic waves, the fault parameters of the main shock were determined. The fault plane solutions of 150 small earthquakes, occurring within a period of 18 months before and after the main shock have been obtained from the amplitudes of the first motion of P wave. The directions of the earthquake generating stress of about 2000 small earthquakes were determined by smoothing the first motion patterns. Displacement field and stress field in the rock bodies underneath the reservoir caused by the load-ing of the reservoir water have been calculated.. Variations of the velocity ratio of the P and S waves prior to the main shock and several strong aftershocks were ana-lysed.In consideration of the seismicity as well as the geological background, we endeavour to discuss the cause of reservoir impounding earthquakes at Xinfengjiang. We have the opinion that the penetration of water along fissures becomes the most important factor causing the main shock of March 19, 1962 at Xinfengjiang.更多还原