三峡蓄水进程中库首区地震活动与库水位的关联性研究  

Analysis of the Cross-Correlation between Seismicity and Water Level at the Head Area of the Three Gorges Reservoir in the Impoundment Process

作　　者：孟庆筱 姚运生 廖武林[4] 张丽芬[4] 党学会[2] MENG Qingxiao;YAO Yunsheng;LIAO Wulin;ZHANG Lifen;DANG Xuehui(Institute of Geophysics,CEA,5 South-Minzudaxue Road,Beijing 100081,China;The First Monitoring and Application Center,CEA,7 Naihuo Road,Tianjin 300180,China;Institute of Disaster Prevention,465 Xueyuan Street,Sanhe 065201,China;Institute of Seismology,CEA,40 Hongshance Road,Wuhan 430071,China)

机构地区：[1]中国地震局地球物理研究所,北京市100081 [2]中国地震局第一监测中心,天津市300180 [3]防灾科技学院,河北省三河市065201 [4]中国地震局地震研究所,武汉市430071

出　　处：《大地测量与地球动力学》2021年第7期714-720,共7页Journal of Geodesy and Geodynamics

基　　金：中国长江三峡集团有限公司项目(0799217);国家自然科学基金(41772840)。

摘　　要：利用三峡数字遥测地震台网产出的地震观测资料,基于互相关-重排实验技术系统分析三峡工程在蓄水进程中地震活动与库水位的相关性及不确定度,探讨三峡水库地震的成因机制。结果表明:1)蓄水进程中库首区地壳经历了“持续加载-渗透饱水-回弹与再平衡”的复杂过程,库区地震活动的时空分布特征与库水位的时序变化关系密切;2)从开始蓄水到175 m实验性蓄水阶段,巨量的直接库水荷载导致沿江近库岸10 km范围内的矿洞、溶洞、浅表性岩层、断层等失稳而诱发地震,震源深度5 km范围内的浅震活动明显与库水位快速上升产生的弹性加载有关,对库水位上涨呈“瞬时”响应;3)随着175 m实验性蓄水阶段稳定运行,渗透作用逐渐成为库区地震活动的主要影响因素,断层软化等作用可能是接连触发2014-03秭归M4.5、M4.9等构造型水库地震的原因,震源深度大于5 km的深震活动开始呈现对库水位的“滞后”响应特征。长江香溪库段作为仙女山、九畹溪断裂与长江交会的三角形构造部位,其周缘或存在发生中等强度地震的危险性。Based on the seismic observation data from the Three Gorges digital seismic network,the cross-correlation and uncertainty between the seismicity and water level of the Three Gorges project in the impoundment process are systematically analyzed using the cross-correlation and rearrangement experiment technology,and the genetic mechanism of earthquakes in the Three Gorges reservoir is discussed.The results show that:1)During the impoundment process,the crust of the reservoir head area experiences a complex process of“continuous loading-seepage saturation-rebound and rebalancing”.The spatial-temporal distribution of seismicity in the reservoir area is closely related to the temporal variation of reservoir water level.2)From the beginning of impoundment to the 175 m experimental impoundment stage,the huge direct reservoir water load leads to the instability of mine caves,karst caves,shallow rock strata,faults and so on within 10 km along the river bank,thus inducing earthquakes.The shallow seismicity within 5 km of focal depth is obviously related to the elastic loading caused by the rapid rise of reservoir water level,showing an“instantaneous”response to the rise of reservoir water level.3)With the stable operation of reservoir water in the 175 m experimental impoundment stage,reservoir water seepage gradually becomes the main influencing factor of seismic activity in the reservoir area,and the fault softening may be the reason for triggering the Zigui M4.5,M4.9 structural reservoir earthquakes in March 2014.The deep earthquake activity with focal depth greater than 5 km has a“lag”response to the reservoir water level.The Xiangxi reservoir section of the Yangtze river is a triangle structural area where Xiannüshan fault,Jiuwanxi fault and the Yangtze river intersect.There is a risk of medium-magnitude earthquake around this area.

关 键 词：水库地震 三峡库首区 水位 相关性 时滞 

分 类 号：P315[天文地球—地震学]