| 三峡库区秭归与巴东交界Ms4.0地震矩张量及应力环境研究 |
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| 引用本文： | 吴海波,王杰,邹正波,陈俊华.三峡库区秭归与巴东交界Ms4.0地震矩张量及应力环境研究[J].地球物理学报,2021,64(2):484-497. |
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| 作者姓名： | 吴海波 王杰 邹正波 陈俊华 |
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| 作者单位： | 中国地震局地震研究所(地震大地测量重点实验室),武汉430071;湖北省地震局,武汉430071;中国地震局地震研究所(地震大地测量重点实验室),武汉430071 |
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| 基金项目： | 中国地震局地震研究所所长基金面上项目 |
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| 摘 要： | 三峡库区湖北秭归与巴东交界地区2013年以来发生5次M S4.0以上地震.本文基于湖北、重庆等省属13个测震台站宽频带波形数据,采用kiwi软件包和rapidinv12程序反演了这些地震的全矩张量解,结果显示所有地震双力偶解均为走滑兼逆断性质,两个节面走向、倾角、滑动角与P、T轴走向和倾俯角的一致性均较好,主压应力P轴NWW走向,倾角近水平,主张应力T轴NNE走向.与三峡库区现今构造应力场比较,这5次地震主压应力P轴与主张应力T轴的平均方向与其大体一致,并且节面1平均走向也与附近主要断裂:高桥断裂和周家山—牛口断裂走向大体一致,反映了这些地震受到区域现今构造应力环境的控制与影响.通过对地震矩张量的ISO+DC+CLVD分解显示,所有地震的ISO成分均低于10%,纯双力偶DC成分偏少而CLVD成分较多,主要与震源区地下浅层介质复杂的各向异性、多重剪切错动或液态下拉张错动有关.结合震源区局部特殊的岩层岩性结构和水文地质环境,分析认为库水长时期的侵蚀溶蚀与加卸荷载作用,有利于引起局部岩层强度降低,在特殊水位时段将触发岩层失稳而滑动破裂,这5次地震中CLVD成分较多正是这一复杂过程的重要体现.
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| 关 键 词： | kiwi方法 全矩张量 CLVD 构造应力环境 |
Moment tensors and the stress environment of Ms4.0 earthquakes in the junction area between Zigui and Badong,Three Gorges Reservoir |
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| WU HaiBo,WANG Jie,ZOU ZhengBo,CHEN JunHua.Moment tensors and the stress environment of Ms4.0 earthquakes in the junction area between Zigui and Badong,Three Gorges Reservoir[J].Chinese Journal of Geophysics,2021,64(2):484-497. |
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| Authors: | WU HaiBo WANG Jie ZOU ZhengBo CHEN JunHua |
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| Institution: | (Key Laboratory of Earthquake Geodesy,Institute of Seismology,CEA,Wuhan 430071,China;Earthquake administration of Hubei Province,Wuhan 430071,China) |
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| Abstract: | Five MS4.0 earthquakes have occurred at the junction area between Zigui and Badong in the Three Gorges Reservoir since 2013.In this paper,kiwi software package and rapidinv12 program are used to invert the full moment tensor solutions of these events based on broadband waveforms of 13 seismic stations in Hubei and Chongqing.The results show that all the seismic double couple solutions are strike-slip with thrust component.The strikes,dips,slip angles of two nodal planes and strikes,plunges of P and T axes are consistent with each other.The principal compressive stress P-axis direction is NWW,the plunge angle is nearly horizontal,and the principal tensile stress T-axis direction is NNE.Compared with the present tectonic stress field in the Three Gorges Reservoir area,the average directions of the principal compressive stress and the principal tensile stress of five earthquakes are roughly the same.Moreover,the average strike of nodal plane 1 is similar to that of the nearby major faults:Gaoqiao fault and Zhoujiashan-Niukou fault,reflecting that these earthquakes are controlled and influenced by the present regional tectonic stress environment.The ISO+DC+CLVD decomposition of seismic moment tensors shows that the ISO components of all the earthquakes are less than 10%,while the pure double couple DC components are less and the CLVD components are more,which are mainly related to complex anisotropy,multiple shear dislocation or liquid tension dislocation of shallow media in the source area.Combining with the local special lithological structure and hydrogeological environment in the focal area,it is considered that the erosion and corrosion and the loading and unloading of reservoir water over a long time are favorable to the reduction of local rock strength,which could trigger the rock instability and sliding fracture in the special water level period.The relatively many CLVD components in these five earthquakes are the important manifestation of this complex process. |
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| Keywords: | kiwi method Full moment tensor CLVD Tectonic stress environment |
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