龙滩水库库区地震活动与水位的互相关分析及孔隙压力扩散系数估算  

Analysis of the cross-correlation between seismicity and water level and estimation of the hydraulic diffusivity in the Longtan reservoir area

作　　者：叶庆东[1] 余大新[1] 王凯明 毛远凤[1] 阎春恒 Ye Qing dong;Yu Daxin;Wang Kaiming;Mao Yuanfeng;Yan Chunheng(The First Monitoring and Application Centre,China Earthquake Administration,Tianjin 300180,China;Earthquake Agency of Guangxi Zhuang Autonomous Region,Nanning 530022,China)

机构地区：[1]中国地震局第一监测中心,中国天津300180 [2]广西壮族自治区地震局,中国南宁530022

出　　处：《地震学报》2023年第6期1068-1078,共11页Acta Seismologica Sinica

基　　金：中国地震局星火计划(XH21050Y)资助.

摘　　要：对广西壮族自治区龙滩水库库区2013年3月1日至2019年10月31日的地震数目与水位进行互相关计算,得到了地震活动对库区蓄水响应的延迟时间为37天,并通过替代数据检验确认了其可靠性。37天的延迟时间说明在水位达到峰值后地震活动开始快速增强,可能暗示着现阶段库水流体作用的影响主要局限在库区内。根据延迟时间和地震深度分布,以及周期性边界条件下孔隙压力扩散方程的解,在不考虑孔隙压力扩散与应力耦合时得到孔隙压力扩散系数D=(8.66±4.11)m2/s;在考虑孔隙压力扩散与应力耦合时得到扩散系数D=(1.72±0.82)m2/s。后者在物理上更为合理,说明现阶段孔隙压力扩散与应力耦合可能是诱发龙滩库区水库地震的主要因素。In this study,the 37-day time lag was estimated by cross-correlating the daily number of earthquakes and the daily water level data from 1 March 2013 to 31 October 2019 in the Longtan reservoir,Guangxi Zhuang Autonomous Region.Based on the surrogate data test,we confirmed the 37-day time lag was reliable.The 37-day time lag indicates reservoir-induced enhances seismic activity rapidly after the water level reaches peak value,which may suggest the fluid effect of reservoir water is mainly confined within the reservoir area at present.With the time lag,the depth distribution of the earthquakes,and the solutions of pore pressue diffusion equations derived under periodic boundary condition,the vertical hydraulic diffusivity were estimated to be D=(8.66±4.11)m2/s and D=(1.72±0.82)m2/s on the condition that the pore pressure diffusion uncoupled and coupled the stress,respectively.The latter is more reasonable physically,which may indicate the coupling between diffusion of the pore pressure and stress is the main reason for inducing the earthquakes in the Longtan reservoir at present stage.

关 键 词：龙滩水库 互相关系数 替代数据 扩散方程 孔隙压力扩散系数 

分 类 号：P315.1[天文地球—地震学]