复杂构造环境下水库地震活动性研究——以糯扎渡水电站为例  

Study on Seismic Activity of Reservoir in Complex Tectonic Environment——Take Nuozhadu Hydropower Station as An Example

作　　者：李丹 李黎 叶建庆[1] Li Dan;Li Li;Ye Jianqing(Yunnan Seismological Bureau,Kunming 650244,China;Huaneng Lancang River Hydropower Inc.,Kunming 650000,China)

机构地区：[1]云南省地震局,昆明650224 [2]华能澜沧江公司,昆明650000

出　　处：《震灾防御技术》2023年第3期548-558,共11页Technology for Earthquake Disaster Prevention

摘　　要：糯扎渡水电站位于澜沧江中下游,该地区构造环境复杂,活动断层发育,地震频发。本文利用区域构造、糯扎渡库区水荷载变化、云南省区域地震台网2000-2021年地震监测资料,对糯扎渡水库区域断层性质、库水位荷载变化、地震震源参数和水库蓄水前后的地震活动空间等进行综合分析。研究结果表明,糯扎渡水库影响区及附近区域活断层密集,构造环境复杂且存在应力水平较高区域,蓄水前库区地震活动强度较高。伴随蓄水量的增加,微小地震活动频度和强度逐渐增强,显示出蓄水对库区内断层上的应力分布具有明显的扰动作用。蓄水后水库坝区附近和澜沧江库区中段窝拖寨断层区的地震活动频度和强度有所增强,普洱大河库段地震活动强度则低于区域背景地震,但微小地震活动的频度有所上升,且与库水位的周期性变化有一定的相关性。地震活动的空间位置与库区内复杂的构造断层密切相关。在区域构造应力和库区水加、卸载的共同作用下,构成了糯扎渡水库影响区微小地震时间、空间、强度的活动图像。未来区内地震活动仍将受到区域构造应力影响和水位变化及水的渗透作用影响,其地震活动强度可能达到5.0级左右。Nuozhadu Hydropower Station(NHS)is located at the middle and lower reaches of the Lancang River,where the tectonic environment is complex with massive active faults and frequent earthquakes.In this paper we comprehensively analyzed the characteristics of regional faults,the variation of water level load in NHS,focal parameters,and the spatial distribution,frequency and intensity of seismicity before and after impoundment,based on the regional tectonics,the variation of water load,and the seismic monitoring data of Yunnan regional seismic network from 2000 to 2021.The results show that the affected areas in and around the reservoir have densely distributed active faults and tectonic environment with high stress level,and higher intensity of seismic activities before impoundment.The frequency and intensity of micro-seismic activities gradually increase on the rise of water level,indicating that water storage has a significant disturbance on the stress distribution along the faults.After impoundment,however,the intensity of seismic activities is lower than that of regional background earthquakes,but the frequency of micro-earthquakes increases and intensifies,which is correlated with the periodic change of reservoir water level.The spatial distribution of seismic activities is closely related to the complex faults in the area.The activity pattern of time,space and intensity of micro-earthquakes in the affected area of NHS are constructed by the joint action of regional tectonic stress and water loading and unloading.Seismicity in the region will still respond to the regional tectonic stress,the change of water level and the infiltration of water in the future and the magnitude may reach about M5.0.

关 键 词：糯扎渡水库 活动构造环境 地震活动性 构造应力 水库地震 

分 类 号：TV697.24[水利工程—水利水电工程]