文章摘要

文章信息/Info

作者:: 张博¹; 6; 王宝善¹; 2; 3; 李璐¹; 魏斌⁴; 苏金波¹; 4; 5; (1.中国地震局地球物理研究所,北京 100081; 2.中国科学技术大学地球和空间科学学院,安徽合肥 230026; 3.中国科学技术大学安徽蒙城地球物理国家野外科学观测研究站,安徽合肥 230026; 4.新疆维吾尔自治区地震局,新疆乌鲁木齐 830011; 5.中国地震局乌鲁木齐中亚地震研究所,新疆乌鲁木齐 830011; 6.防灾科技学院地球科学学院,河北三河 065201)

Author(s):: ZHANG Bo¹; 6; WANG Baoshan¹; 2; 3; LI Lu¹; WEI Bin⁴; SU Jinbo¹; 5; 4; (1.Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)(2.School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China)(3.Mengcheng National Geophysical Observatory,University of Science and Technology of China,Hefei 230026,Anhui,China)(4.Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,Xinjiang,China)(5.Urumqi Institute of Central Asia Earthquake,China Earthquake Administration,Urumqi 830011,Xinjiang,China)(6.School of Earth Sciences,Institute of Disaster Prevention,Sanhe 065201,Hebei,China)

Keywords:: the Nurga Reservoir; micro-earthquake detection; waveform cross-correlation; earthquake location; seismicity

摘要:: 水库库区附近的地震活动性对水库的安全运行有重要影响。为了进一步理解构造活跃区地震活动与水库蓄水的关系,以新疆努尔加水库为例,采用模版匹配滤波方法对2014—2018年库区附近的地震事件进行了检测,完备震级(M_C)由检测前的1.1降低至0.5,b值为0.86。利用双差定位法对检测事件中的1 064个事件进行了重定位,地震定位结果及波形相似性分析显示,水库蓄水后在库区下游形成的两个地震丛集分属于不同的发震构造。受库区东西两侧昌吉背斜和喀拉扎背斜的控制,两丛集地震活动分别位于积累了大量形变的反冲断层上盘和背斜生长行成的膝折带中。地震活动在时间上还与蓄水水位的周期性变化相关。根据地震活动时空演化特征推断,库水沿着砂砾岩层向下渗流,改变了介质强度或断层的摩擦阻力,促使构造应力的释放,这是地震活动增加的主要物理机制。

Abstract:: Reservoirs located in the area with active tectonics are threatened by both tectonic earthquakes and reservoir-triggered earthquakes.To further understand the relationship between the reservoir impoundment and the seismicity in the active tectonic zone,we detected the earthquake events around the Nurga Reservoir from 2014 to 2018 using the matched filter technique(MFT)and the double-difference location(hypoDD)method.As a result,the minimum magnitude of completeness(M_C)dropped from 1.1 to 0.5,while b-value was 0.86.More than 2 600 events were detected and 1 064 of them were relocated.Two earthquake clusters occurred within 5 km in the lower reaches of the Nurga Reservoir area after the Reservoir's impoundment.They were generated by different seismogenic structures controlled by the Changji anticline and the Kalazha anticline respectively.The seismicity in this area correlated well with the periodic changes of the Reservoir's water level.The water flows along the glutenite layer to the earthquake source area,causing the tectonic stress release.This is the main reason for the seismicity in the reservoir area.