地震地质 ›› 2017, Vol. 39 ›› Issue (3): 437-450.DOI: 10.3969/j.issn.0253-4967.2017.03.001

• 研究论文 • 上一篇    下一篇

探讨水头增量及其变化率对水库诱发地震活动的影响-以紫坪铺水库为例

刘远征1,2, 马瑾2, 马文涛2, 姜彤1   

  1. 1 华北水利水电大学资源与环境学院, 郑州 450045;
    2 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029
  • 收稿日期:2016-06-16 修回日期:2016-07-13 出版日期:2017-06-20 发布日期:2017-07-20
  • 作者简介:刘远征,男,1978年生,2014年于中国地震局地质研究所获构造物理学博士学位,讲师,主要研究与蓄水、注水等相关的诱发地震问题,电话:0371-69127351,E-mail:expedition@163.com。
  • 基金资助:
    国家自然科学基金(41572181)、中央级公益性科研院所基本科研业务专项(IGCEA1415)、华北水利水电大学高层次人才引进项目(40476)与中国地震局地震科技近期重点突破方向专项经费共同资助

INFLUENCE OF PRESSURE HEAD CHANGE AND ITS CHANGE RATE ON RESERVOIR TRIGGERED SEISMICITY -A CASE STUDY OF ZIPINGPU RESERVOIR

LIU Yuan-zheng1,2, MA Jin2, MA Wen-tao2, JIANG Tong1   

  1. 1 School of Resources and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450045, China;
    2 State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2016-06-16 Revised:2016-07-13 Online:2017-06-20 Published:2017-07-20

摘要: 分析水库蓄水在地震发生中的作用时,首先需要了解水在其中的扩散过程及其作用机理。文中通过紫坪铺水库蓄水后,汶川地震前的小震活动时空演化,探讨水库蓄水诱发地震活动的发生、发展过程及其机理。从比较地震时空分布和水体范围变化开始,进而探讨影响建模计算的各个因素,最后给出计算结果。得出以下几点认识:1)紫坪铺水库蓄水后到汶川地震发生前,水库周围的小震活动与水库蓄水密切相关,并且小震分布在汶川地震的地震断层上。2)受地形和介质的影响,水库影响范围实际上是有限的,并且是各向异性的。因此在建模计算前,半定量地获得了孔隙压力扩散系数,沿断裂走向和倾向分别为0.7m2/s和0.35m2/s;定性地设定了地表约束。3)计算结果表明紫坪铺水库附近地震活动的范围与孔隙压力增量有关。当应力值达到触发地震活动的阈值之后,不论水头增量是否处于高值,地震活动的兴衰皆受控于增量变化率。这表明孔隙压力对震群活动的触发是动态触发。

关键词: 紫坪铺水库, 汶川地震, 触发地震, 压力水头增量变化率, 流体压力扩散系数

Abstract: For analyzing the role that reservoir impounding plays in triggering earthquake, the process of diffusion of pore pressure and its mechanism of action should be understood firstly. The temporal distribution of seismicity, which occurred before the MS8.0 Wenchuan earthquake, following the impoundment of Zipingpu reservoir is studied in this paper. Then the mechanisms of the occurrence and development of reservoir triggered seismicity are discussed. A comparative analysis of the temporal distribution of seismicity and the submerged area by reservoir impounding is carried out firstly. Then the influence of various factors on modeling is analyzed in detail. After calculating, the pore pressure change by the Zipingpu reservoir impoundment is obtained. The following observations are made:(1)Conspicuous swarms of earthquakes, of which the sources are located on the same fault of the MS8.0 Wenchuan earthquake, occurred orderly with the impoundment of Zipingpu reservoir.(2)Because of the influences of the terrain and the medium, the range of effect of pore pressure change by the impoundmemt is limited and anisotropic. Hydraulic diffusivities(D)of 0.7 and 0.35m2/s along the fault strike and the fault dip are reached respectively by a semi-quantitative assessment. Of course, the qualitative pressure constraints on the surface are also applied for the modeling.(3)The calculation results show that the temporal distribution of seismicity near the Zipingpu reservoir is related with the pore pressure change. After the pore pressure reached the threshold of triggering earthquake, whether the pressure head change is high or not, the change rate of pressure head change plays a key role in the decrease or increase of seismicity. It means that the triggered seismicity by pore pressure is a dynamic triggering process.

Key words: Zipingpu reservoir, Wenchuan earthquake, triggered seismicity, change rate of pressure head change, fluid diffusion coefficient

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