李家峡水库蓄水后区域地震活动特征及危险性分析

根据李家峡水库地震台网1998-2002年的地震目录,分析了水库蓄水后库坝区和周边研究区的地震活动特征,并对未来水库地震的危险性进行了定量评价.分析结果表明:李家峡水库蓄水以来,库坝区90%的地震为0.0～1.9级的弱小地震,且地震活动与水库水位有关,相对于水位升高存在5～7个月的滞后期;研究区以1.0～1.9级地震为主,地震活跃程度呈间息式变化,地震月频次呈阶跃式变化.应用经验判别法的预测结果表明,未来李家峡水库库坝区存在诱发5级以上灾害性地震的危险性,最大震级在5.0～5.4级之间.

Characteristics of Lijiaxia reservoir earthquake and its seismicity riskness evaluation

The present paper has done an analysis and study on the characteristics of earthquakes that have occurred in Lijiaxia reservoir region in the Yellow River Basin in recent years based on statistics and data collected by a seismic network of from May 1998 to December 2002. The riskness of the reservoir seismicity in future is also predicated. The results obtained show that since Lijiaxia is water-filled in 1997, M_L 0-1.9 earthquakes accounts up 90% of the total earthquakes in the reservoir region. Furthermore, these microseismicities prove to be closely connected with the water level of the reservoir and have a 5-7 months lag with changes of the water level. The main magnitude of earthquakes in the studied region is M_L 1.0-1.9, and seismicity frequency is sultant. As predicated, the destructive shock would occur in Lijiaxia reservoir and the largest magnitude of reservoir earthquake in future is M_L 5.0-5.4.