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地震 ›› 2017, Vol. 37 ›› Issue (3): 1-11.

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利用粘弹性球体位错理论研究2011年日本MW9.0地震引起的震后位移时空变化

刘泰1, 付广裕1, 2*, 苏小宁1, 3   

  1. 1.中国地震局地震预测重点实验室, 地震预测研究所, 北京 100036;
    2.中国科学院计算地球动力学重点实验室, 北京 100049;
    3.同济大学测绘与地理信息学院, 上海 200092
  • 收稿日期:2016-09-19 发布日期:2019-08-09
  • 通讯作者: 付广裕, 研究员。 E-mail: fugy@cea-ies.ac.cn
  • 作者简介:刘泰(1992-), 男, 湖北荆州人, 在读硕士研究生,主要从事地震位错形变研究。
  • 基金资助:
    国家自然科学基金(41574071); 国家国际科技合作专项项目(2105DFR21100); 中国地震局地震预测研究所基本科研业务费专项(2015IES0302, 2012IES010305)

Post-seismic Displacements Induced by the 2011 Tohoku-Oki MW9.0 Earthquake based on Visco-elastic Spherical Dislocation Theory

LIU Tai1,FU Guang-yu1,2,SU Xiao-ning1,3   

  1. 1.Key Laboratory of Earthquake Prediction, Institute of Earthquake Science, CEA, Beijing 100036, China;
    2.Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049, China;
    3.College of Surveying and Geo-informatics, Tongji University, Shanghai 200092, China
  • Received:2016-09-19 Published:2019-08-09

摘要: 基于2011年3月~2015年9月的GPS观测数据, 研究了2011年日本MW9.0地震引起的震后位移时空变化, 分析震后4.5 a内震后断层余滑和粘滞性松弛对震后位移场的贡献。 基于子断层叠加的思想, 对Tanaka的粘弹性球体位错理论配套计算程序(环型解部分)加以改进, 克服其近场计算精度不足(甚至错误)的缺陷, 提高了近场震后位移的计算精度。 利用弹性球体位错理论配套计算程序和改进后的粘弹性球体位错理论配套计算程序, 分别计算2011年日本MW9.0地震产生的同震位移, 两组结果的差异仅占信号的1%左右, 验证了对粘弹性球体位错理论配套计算程序改造的正确性。 最后, 结合震后3~4.5 a GPS观测数据, 利用Tanaka的粘弹性球体位错理论确定了2011年日本MW9.0地震震中周边区域地幔粘滞性系数, 其最佳拟合值为6×1018 Pa·s。

关键词: 球体位错理论, GPS, 位移, 地幔粘滞性系数, 2011年日本MW9.0地震

Abstract: In the present study, we extracted the post-seismic displacements caused by the 2011 Tohoku-Oki MW9.0 earthquake from GPS observations. The data spans from March 2011 to September 2015. We studied the contributions of afterslip and visco-elastic relaxation on the post-seismic displacements within 4.5 years after the main shock. We updated the software of Tanaka using a segment-summation scheme, improving the computation accuracies in the near-field. We calculated the co-seismic Green functions of the vertical and horizontal displacement at the source depth of 32 km, using the visco-elastic dislocation theory of Tanaka and elastic spherical dislocation theory of Sun, respectively. The results indicate that these two sets of Green functions are consistent with each other. The differences between the two sets of Green functions are within the uncertainty of the computation. This fact confirmed the correctness of our new software. Then we simulated the post-seismic displacements from March 2014 to September 2015, which are mainly caused by the visco-elastic relaxation of the Mantle. Comparing the observed displacements with the simulated ones, we found that the optimal viscosity of the Mantle around the epicenter region is about 7×1018 Pa ·s.

Key words: Spherical dislocation theory, GPS, 2011 Tohoku-Oki MW9.0 earthquake, Displacement, Viscosity of the Mantle

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