地震地质 ›› 2016, Vol. 38 ›› Issue (1): 121-130.DOI: 10.3969/j.issn.0253-4967.2016.01.009

• 研究论文 • 上一篇    下一篇

2014年3月湖北省秭归县M4.2、M4.5地震成因分析

王秋良1,2, 张丽芬1,2,3, 廖武林1,2, 李井冈1,2,3   

  1. 1. 中国地震局地震研究所, 地震与大地测量重点实验室, 武汉 430071;
    2. 三峡工程生态与环境监测系统地震监测重点站, 武汉 430071;
    3. 中国地震局地球物理研究所, 北京 100081
  • 收稿日期:2015-10-26 出版日期:2016-03-20 发布日期:2016-05-17
  • 通讯作者: 张丽芬,副研究员,E-mail:270152675@qq.com
  • 作者简介:王秋良,1972年生,2007年毕业于中国地质大学(武汉),获博士学位,副研究员,现主要从事地震地质、水库诱发地震等方面的研究,电话:13657278367,E-mail:wql0703@163.com。
  • 基金资助:

    中国长江三峡集团公司科研专项基金(SXSN2377,SXSN3354)资助

RESEARCH ON GENESIS OF M4.2 AND M4.5 EARTHQUAKE SEQUENCES IN MARCH 2014 IN ZIGUI COUNTY, HUBEI PROVINCE

WANG Qiu-liang1,2, ZHANG Li-fen1,2,3, LIAO Wu-lin1,2, LI Jing-gang1,2,3   

  1. 1. Key Laboratory of Earthquake Geodesy, Institute of Seismology, China Earthquake Administration, Wuhan 430071, China;
    2. Key Seismic Monitoring Station of the Ecological and Environmental Monitoring System of Three Gorges Project, Wuhan 430071, China;
    3. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
  • Received:2015-10-26 Online:2016-03-20 Published:2016-05-17

摘要:

2014年3月27日和3月30日,三峡库首区秭归县分别发生M4.2和M4.5地震,震中相距约1km,地震序列类型为双震型。地震发生在175m试验性蓄水库水位缓慢下降阶段,G-R关系显示地震序列的b值与该地区构造地震的b值较为接近。为了检验库水对地震的影响,利用ETAS模型检验了库水对地震的触发作用。结果表明,三峡库水对秭归地震序列有一定的触发作用,但影响较小。利用双差定位法进行地震精定位,结果显示,2地震序列发生在NNW向仙女山断裂与NE向断裂的交会部位,平面上呈共轭展布。采用矩张量反演和P波初动2种方法研究了2次4.0级以上地震的震源机制解,均显示逆走滑性质。结合余震分布特征可知,2地震序列的发震构造分别为NE向节面和NNW向节面。从震源深度剖面分析,M4.2地震序列的发震构造为走向NE,倾角较陡的断层,余震震源深度剖面呈三角形,分析该地震序列在其右侧受到了走向NW界面的约束; M4.5地震序列是在NE向小断层和NNW向仙女山断裂共轭作用影响下发生的。

关键词: 地震序列, 震源深度剖面, 震源机制, ETAS模型

Abstract:

On 27th and 30th March 2014, an M4.2 and M4.5 earthquake sequence occurred in Zigui County, Hubei Province, and the earthquake sequence type is double seismic type. The two earthquake sequences occurred at the water unloading stage of the 175m trial impounding, and G-R relations showed the similar characteristics with that of the tectonic earthquakes. In order to verify the influences of dam reservoir on earthquake triggering, ETAS model was introduced, the results showed that the slow water level changes had little impact on the occurrence of earthquake. Double difference precision relocation results indicated that the two earthquake sequences occurred at the intersection part of a NE-striking fault and the NNW-striking Xiannvshan Fault, and the preferred direction of aftershock distribution was separately NE and NNW. Moment tensor inversion method and P wave initial motion method were used to determine the focal mechanisms of the two earthquakes, and the results indicated that the two earthquakes were controlled by the regional tectonic stress field and were of reverse-slip type. Comprehensive analysis showed that the M4.2 earthquake was caused by a small-scale fault striking NE with a big dip angle. From the hypocenter profile, it can be seen that the M4.2 earthquake sequence was restrained by an east-dip fault, and the M4.5 earthquake sequence was the product under the conjugate action of the NE-striking fault and the NNW-striking Xiannvshan fault.

Key words: earthquake sequence, focal depth profile, focal mechanism, ETAS model

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