| 2013年四川芦山Ms7.0地震前的重力变化 |
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| 引用本文： | 祝意青,闻学泽,孙和平,郭树松,赵云峰.2013年四川芦山Ms7.0地震前的重力变化[J].地球物理学报,2013,56(6):1887-1894. |
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| 作者姓名： | 祝意青 闻学泽 孙和平 郭树松 赵云峰 |
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| 作者单位： | 1. 中国地震局第二监测中心, 西安 710054;
2. 大地测量与地球动力学国家重点实验室, 武汉 430077;
3. 中国地震局地震预测研究所, 北京 100036;
4. 四川省地震局, 成都 610000 |
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| 基金项目： | 国家自然科学基金，地震行业科研专项，国家科技支撑计划课题，大地测量与地球动力学国家重点实验室开放基金 |
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| 摘 要： | 利用川西地区2010-2012年期间的流动重力观测资料,系统分析了区域重力场变化及其与2013年4月20日四川芦山7.0级地震发生的关系.结果主要表明:①区域重力场异常变化与北东向龙门山断裂带南段和北北西向马尔康断裂带在空间上关系密切,反映沿该两断裂带(段)在2010-2012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芦山7.0级地震前,测区内出现了较大空间范围的区域性重力异常,而震源区附近产生了局部重力异常,沿龙门山断裂带南段形成了重力变化高梯度带,其中,宝兴、天全、康定、泸定、石棉一带重力差异变化达100×10-8m·s-2以上;这些可能反映芦山地震前,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重力场差分动态演化图像和重力场累积变化动态图像均反映芦山7.0级地震孕育过程的最后2~3年出现较显著的流动重力异常变化,可视为该地震的中期前兆信息;本文第一作者等也曾基于该流动重力异常变化在芦山7.0级地震前做过一定程度的中期预测,尤其是地点预测.本文的例子再次证明流动重力观测能较好地捕捉到强震孕育发生过程中,特别是该过程最后阶段的重力异常变化信息.因此,区域流动重力场观测对未来强震的中-长期预测,尤其是在发震地点的判定上具有优势.
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| 关 键 词： | 川西地区 重力观测 重力变化 芦山地震 中期前兆 |
| 收稿时间： | 2013-05-02 |
Gravity changes before the Lushan, Sichuan, Ms=7.0 Earthquake of 2013 |
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| ZHU Yi-Qing
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WEN Xue-Ze
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SUN He-Ping
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GUO Shu-Song
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ZHAO Yun-Feng.Gravity changes before the Lushan, Sichuan, Ms=7.0 Earthquake of 2013[J].Chinese Journal of Geophysics,2013,56(6):1887-1894. |
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| Authors: | ZHU Yi-Qing WEN Xue-Ze SUN He-Ping GUO Shu-Song ZHAO Yun-Feng |
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| Institution: | 1. Second Crust Monitoring and Application Center, CEA, Xi'an, 710054 China;
2. State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, CAS, Wuhan 430077, China;
3. Institute of Earthquake Science, CEA, Beijing 100036, China;
4. Seismological Bureau of Sichuan Province, Chengdu 610000, China |
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| Abstract: | Using the observation data of relative gravity measurements in western Sichuan region from 2010 to 2012, we have systematically analyzed the spatial-temporal variation of the regional gravity field and their relation to the occurrence of the Ms=7.0 Lushan earthquake on April 20, 2013. Our research mainly shows that: (1) Spatially the anomaly change of the regional gravity field is closely related to both the southern segment of the NE-trending Longmenshan fault zone and the NNW-trending Markang fault, suggesting that the active tectonic action or deformation happened along the two fault zones (or segments) during 2010 to 2012, which would have induced the variation in the ground gravity observation. (2) Before the Ms=7.0 Lushan earthquake, regional gravity anomaly appeared in the whole study region and local gravity anomalies at and near the potential source area. Among the region and the areas with gravity anomalies, the anomaly variations near Baoxing, Tianquan, Kangding, Luding and Shimian were up to and over 100×10-8m·s-2, apparently reflecting an enhancement of tectonic or stress's action in the study region and at and near the potential source area, that could be related to the preparation and occurrence of the earthquake. (3) The dynamic evolution patterns of the regional gravity changes and those patterns of cumulated gravity variations suggest that significant anomalies of gravity variations in the relative gravity measurements appeared indeed in the last 2 to 3 years in the preparation of the Ms=7.0 Lushan earthquake, and such anomalies can be regarded as one of the medium-term precursory of the earthquake. In a certain degree, the first author of this paper and others once made a medium-term forecast before the Lushan earthquake, especially made a forecast for the locality of the earthquake based on the anomaly gravity variations. The case studied in this article demonstrates again that through relative gravity survey people can catch anomalous gravity variation that would be related to the process of earthquake preparation, especially to those anomaly variations appearing in the last stage of the process. Therefore, relative gravity survey has unique advantages in the medium- to long-term earthquake forecast, especially for forecasting localities of potential earthquakes. |
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| Keywords: | Western Sichuan Gravity observation Gravity variation Lushan earthquake Medium-term precursor |
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