四川锦屏水电站地区的剪切波分裂参数变化

刘莎, 吴朋

刘莎, 吴朋. 2018: 四川锦屏水电站地区的剪切波分裂参数变化. 地震学报, 40(1): 58-66. DOI: 10.11939/jass.20170114
引用本文: 刘莎, 吴朋. 2018: 四川锦屏水电站地区的剪切波分裂参数变化. 地震学报, 40(1): 58-66. DOI: 10.11939/jass.20170114
Liu Sha, Wu Peng. 2018: Changes of shear-wave splitting parameters in Jinping hydro-power station, Sichuan. Acta Seismologica Sinica, 40(1): 58-66. DOI: 10.11939/jass.20170114
Citation: Liu Sha, Wu Peng. 2018: Changes of shear-wave splitting parameters in Jinping hydro-power station, Sichuan. Acta Seismologica Sinica, 40(1): 58-66. DOI: 10.11939/jass.20170114

四川锦屏水电站地区的剪切波分裂参数变化

详细信息
    通讯作者:

    刘莎: e-mail: liusha@cea-igp.ac.cn

  • 中图分类号: P315.3+1

Changes of shear-wave splitting parameters in Jinping hydro-power station, Sichuan

  • 摘要: 通过分析四川锦屏水电站地区2012年1月至2013年12月库区的地震活动性和木里台的剪切波分裂参数变化,研究了水电站3次大规模蓄水对该地区地震活动性和地壳应力的影响. 结果显示:经3次蓄水,该地区的地震活动呈持续增强趋势,最终保持在较高水平,尤其是第二次蓄水之后,地震活动增强最为明显;木里台的快剪切波偏振方向在锦屏水电站3次蓄水前后表现出明显的变化. 锦屏水电站在蓄水之前,木里台快剪切波偏振方向的优势取向为北东向,与锦屏山—小金河断裂走向一致;第一次蓄水之后,快剪切波偏振方向则变得较为分散,无明显的优势取向;第二次蓄水之后,快剪切波偏振方向偏转为南东向;第三次蓄水之后,快剪切波偏振方向表现为一致的南东向;慢剪切波延迟时间在第二次蓄水前后明显变短. 这些显著的变化说明了锦屏水电站第二次蓄水之后原地小范围内的地壳应力方向迅速改变,地壳应力也随着地震活动的增强而释放.
    Abstract: This paper focused on the influences on the seismic activity and the crustal stress caused by three water storages in Jinping hydro-power station, according to the seismic activity in Jinping hydro-power station and the change of shear-wave splitting parameters of the station MLI from January 2012 to December 2013 . The results show that, after three water storages, the seismic activity in this region continued to increase, especially after the second water storage, and finally remained at a high level. Moreover, the polarization direction of fast shear-wave at the seismic station MLI also showed significant changes before and after three water storages of the hydro-power station. Before the water storage of Jinping hydro-power station, the predominant polarization direction at MLI seismic station was northeast, which was in agreement with the strike of Jinpingshan-Xiaojinhe fault. After the first storage, the polarization directions are distributed scatteredly. After the second water storage, the predominant polarization direction changed to southeast. And the polarization directions showed the southeast consistently after the third water storage. As for the station MLI, the delay time of slow shear-wave has changed before and after the three storages of Jinping hydro-power station, especially after the second storage the delay time of slow shear-wave decreased obviously. Thus, the seismic activity, the polarization directions of fast shear-wave and the delay time of slow shear-wave changed significantly after the second water storage of Jinping hydro-power station, suggesting that the direction of crustal stress changed quickly in a small region after the second water storage, and the crustal stress also released with the enhanced seismic activity.
  • 图  1   研究区域内构造背景、地震和台站分布图

    Figure  1.   Tectonic settings,earthquakes distribution and seismic stations in the studied area

    图  2   锦屏水电站水位变化(a)和地震活动(b)对照图

    Figure  2.   Water level change (a) corresponding to seismic activity (b) in Jinping hydro-power station

    图  3   木里台剪切波分裂分析示意图

    (a) 地震波三分向记录,两条红色竖线是图(b)和(c)中截取的剪切波数据段;(b) 水平向剪切波质点偏振图;(c) 快(F)、慢(S)剪切波的质点偏振图

    Figure  3.   The shear-wave splitting analysis of the seismic data recorded by station MLI

    (a) Three-component waveform,where two red vertical lines mark the cut shear-wave section in Figs. (b) and (c);(b) Trail of particle of the shear-wave; (c) Trails of particle of the fast and slow waves

    图  4   木里台快波偏振方向等面积投影玫瑰图

    Figure  4.   Lower hemispherical projection rose diagram of the fast shear-wave polarizations at MLI

    图  5   不同蓄水时期木里台站快剪切波偏振方向等面积投影玫瑰图

    Figure  5.   Lower hemispherical projecton rose diagrams of the fast shear-wave polarizations at MLI station during different water storage periods

    图  6   木里台慢剪切波延迟时间变化结果

    黑点为慢剪切波延迟时间计算值,红色曲线为7点滑动平均值

    Figure  6.   The delay time change of slow shear wave at the seismic station MLI

    The black dots are values of delay time,red line is the result of 7 point moving average

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出版历程
  • 收稿日期:  2017-06-06
  • 修回日期:  2017-09-14
  • 网络出版日期:  2018-02-07
  • 发布日期:  2017-12-31

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