SEISMOLOGY AND GEOLOGY ›› 2014, Vol. 36 ›› Issue (3): 667-676.DOI: 10.3969/j.issn.0253-4967.2014.03.010

• CONTENTS • Previous Articles     Next Articles

DYNAMIC VARIATION OF GRAVITY FIELD BEFORE AND AFTER THE MINXIAN-ZHANGXIAN MS6.6 EARTHQUAKE ON JULY 22, 2013, GANSU, CHINA

ZHU Yi-qing1,2, ZHAO Yun-feng1, LI Tie-ming3, LIANG Wei-feng1, XU Yun-ma1, GUO Shu-song1   

  1. 1. Second Crust Monitoring and Application Center, China Earthquake Adiministration, Xi'an 710054, China;
    2. State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China;
    3. Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2013-12-31 Revised:2014-04-28 Online:2014-09-30 Published:2014-09-30

2013年甘肃岷县漳县6.6级地震前后重力场动态变化

祝意青1,2, 赵云峰1, 李铁明3, 梁伟锋1, 徐云马1, 郭树松1   

  1. 1. 中国地震局第二监测中心, 西安 710054;
    2. 中国科学院测量与地球物理研究所, 大地测量与地球动力学 国家重点实验室, 武汉 430077;
    3. 中国地震局地质研究所, 北京 100029
  • 作者简介:祝意青|男|1962年生|1983年毕业于武汉测绘学院大地测量系|获学士学位|研究员|主要从事重力测量与地球动力学及地震分析预报研究|E-mail:zhuyiqing@ 163.com。
  • 基金资助:

    中国地震局地震行业科研专项(201308009)、国家自然科学基金(41274083,41374026)和大地测量与地球动力学国家重点实验室开放基金(SKLGED201331E)共同资助。

Abstract:

Using the observation data of relative gravity measurements from the northeastern edge of the Tibetan plateau, we have systematically analyzed the spatial-temporal variation of the regional gravity field and their relation to the occurrence of the MS 6.6 Minxian-Zhangxian earthquake on July 22, 2013. Our research mainly shows that: 1)Spatially the anomaly change of the regional gravity field is closely related to the major fault zones in the region, suggesting that the tectonic activities or deformation which happened along the fault zones(or segments)during 2011 to 2013 would have resulted in the variation in the ground gravity observations. 2)Before the MS 6.6 Minxian-Zhangxiang earthquake, regional gravity anomaly firstly appeared in the whole study region, and then local gravity anomalies and high gradient zone of gravity change appeared at and near the potential source area. Among the areas of gravity anomalies, the anomaly variations near Linxia and Minxian were up to and over 150×10-8ms-2, indicating possibly the tectonic movement or stress enhancement in the study region and around the potential source area, which could be related to the preparation and occurrence of the earthquake. 3)The dynamic change patterns and the differential evolution patterns of gravity variation of one year scale suggest that significant anomalies of gravity variations in the mobile gravity measurements appeared indeed in the last two years of the preparation process of the MS 6.6 Minxian-Zhangxian earthquake. The earthquake occurred on the NE-trending high gradient zone near the zero curve and the turning part of contours of gravity change. 4)To a certain degree, we made a medium-term forecast before the Minxian-Zhangxian MS 6.6 earthquake, especially a forecast for the locality of the earthquake based on the anomalous gravity variations.

Key words: northeastern edge of the Tibetan plateau, Minxian-Zhangxian MS 6.6 earthquake, gravity observation, gravity variation, tectonic activity

摘要:

利用青藏高原东北缘2011—2013年期间的流动重力观测资料,系统分析了区域重力场动态变化及其与2013年7月22日岷县漳县6.6级地震发生的关系。结果表明:1)测区内重力场异常变化与主要断裂带在空间上关系密切,反映沿主要断裂带(段)在2011—2013年期间发生了引起地表重力变化效应的构造活动或变形。2)岷县漳县6.6级地震前,测区内先出现了较大空间范围的区域性重力异常,后在震源区附近产生了局部重力异常及重力变化高梯度带,其中,甘肃临夏与岷县一带重力差异变化达150×10-8ms-2 以上;这些可能反映岷县漳县地震前,区域及震源区附近均产生与该地震孕育、发生有关的构造运动或应力增强作用。3)重力场1a尺度动态变化图像和差分动态演化图像均反映岷县漳县6.6级地震孕育过程的最后2a出现较显著的流动重力异常变化,地震发生在NE向重力变化高梯度带上、重力变化零值线附近和等值线的拐弯部位。4)基于流动重力异常变化在岷县漳县6.6级地震前做过一定程度的中期预测,尤其是地点判定。

关键词: 青藏高原东北缘, 岷县漳县6.6级地震, 重力观测, 重力变化, 构造活动

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