SEISMOLOGY AND GEOLOGY ›› 2015, Vol. 37 ›› Issue (3): 780-791.DOI: 10.3969/j.issn.0253-4967.2015.03.009

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DISCUSSION ON SEISMOGENIC STRUCTURES AND SEISMIC ACTIVITY PROCESS BEFORE THE YUTIAN MS7.3 EARTHQUAKE ON FEBRUARY 12, 2014, XINJIANG

SONG Chun-yan1,2, MA Jin1, RAN Hui-min2, HUANG Fu-qiong3   

  1. 1 State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
    2 Earthquake Administration of Xinjiang Uygur Autonomous Region, Urumqi 830011, China;
    3 China Earthquake Networks Center, Beijing 100045, China
  • Received:2014-07-28 Revised:2015-07-30 Online:2015-09-20 Published:2015-10-20

2014年新疆于田7.3级地震发震构造和震前地震活动过程讨论

宋春燕1,2, 马瑾1, 冉慧敏2, 黄辅琼3   

  1. 1 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;
    2 新疆维吾尔自治区地震局, 乌鲁木齐 830011;
    3 中国地震台网中心, 北京 100045
  • 作者简介:宋春燕,女,1978年生,2008年于新疆大学数学与系统科学学院获硕士学位,现为中国地震局地质研究所博士研究生,工程师,主要从事数字地震学和地震预测等方面的工作,E-mail:songchunyan1@163.com.
  • 基金资助:

    国家自然科学基金(41172180)和地震动力学国家重点实验室开放课题(LED2014B01)共同资助

Abstract:

The Yutian MS7.3 earthquake occurred on February 12, 2014 in Xinjiang Uygur Autonomous Region, China and the epicenter is located in the western part of Altyn Tagh Fault. This is the second M≥7 earthquake following the March 21, 2008 Yutian MS7.3 earthquake in the south of the Tarim Basin. Aftershocks of this Yutian MS7.3 earthquake are distributed mainly along the NE direction, and that in the southwest part of the aftershock area presents a near-NS distribution. Most of the aftershocks including foreshocks (accounting for 85% of the total aftershock sequence) are densely distributed in the southwest of the aftershock zone, the vast majority of strong aftershocks (all of the MS≥5 and 81% magnitude 4 earthquakes)are distributed in this area. Aftershocks of the first day are mainly distributed in this area and in a near-NS distribution. The aftershocks extended from west to east. The authors noted that there occurred several M5~M6 earthquakes in 1982, 2011 and 2012 along the near-NS direction of this Yutian earthquake and this Yutian earthquake filled up the empty section. Based on the regional tectonic environment, earthquake focal mechanism solutions and aftershocks distribution, etc., we analyzed the process of this earthquake and found that the earthquake occurred at the branch fault of Altyn Tagh Fault zone on the south margin of Xiaoerkule Basin. Affected by the tectonic stress of Altyn Tagh Fault zone, Xiaoerkule Basin suffers the local near east-west extension, earthquake rupture occurred first along the near-NS direction, the unlocking of this tectonic position promotes the left-lateral movement of the Altyn Tagh Fault, producing NE-oriented rupture, and stress transferring to the east. This paper also discusses the seismogenic structures of historical earthquakes above MS7 occurring on the Altyn Tagh Fault zone and their impact on the fault zone.

Key words: Yutian MS7.3 earthquake, Altyn Tagh Fault, aftershock distribution, tectonic background

摘要:

2014年2月12日在新疆于田发生7.3级地震, 震中位于阿尔金断裂西段, 这是继2008年3月21日于田7.3级地震后在塔里木盆地南侧发生的第2次7级地震.这次于田7.3级地震的余震主体沿NE向分布, 余震区的西南段呈近SN向分布; 绝大部分余震与前震在余震区西南密集分布, 强余震(全部的5级以上地震和81%的4级地震)绝大多数都分布在这个区域, 第1天的余震主要在这个区域呈近SN向分布, 余震由西向东扩展.在这次于田地震的近SN方向上曾在1982、2011以及2012年先后发生过几次6级左右的地震, 而这次地震填补了其中的空段.文中从区域构造环境、地震震源机制解和余震分布特征等方面, 分析这次地震的发震过程, 认为地震发生在硝尔库勒盆地南缘的分支断裂, 受阿尔金断裂带构造应力影响, 硝尔库勒盆地受到局部近EW向的拉张作用力, 首先沿近SN向破裂, 这个构造部位的解锁, 促进阿尔金断裂左旋错动, 产生NE向破裂, 应力向东传递; 文中还对有历史记录以来, 阿尔金断裂上7级地震的发震构造及其对阿尔金断裂带的影响进行了讨论.

关键词: 于田地震, 阿尔金断裂, 余震分布, 构造背景

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