论文部分内容阅读
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。
Seismicity of the Xinfengjiang Reservoir in Guangdong Province increased greatly after the impoundment. Most of the earthquakes occurred in the deepwater canyon area near the dam, forming a dense belt in the northwestern direction with a very shallow focal depth. Afterwards, Two and a half years on March 19, 1962 occurred a magnitude 6.1 earthquake. The fault parameters of the main shock were determined according to the data of leveling and seismic wave spectrum. The initial settlement amplitude of P wave was used to determine the fault surface solution of 150 small earthquakes within 18 months before and after the main shock. The earthquake stress direction of more than 2,000 small earthquakes was calculated; the displacement field and stress field of the reservoir load in the bedrock body were calculated; the change of velocity ratio between the longitudinal and transverse waves of the main shock and several large aftershocks was analyzed . The seismogenic mechanism of Xinfengjiang Reservoir was discussed based on the seismicity and geological background. It is concluded that the infiltration of water is the main reason for the earthquake.