| 2019年甘肃夏河Ms5.7地震前重力场变化 |
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| 引用本文： | 赵云峰,祝意青,刘芳,徐云马,张国庆,毛经伦,朱辉.2019年甘肃夏河Ms5.7地震前重力场变化[J].地震,2021,41(1):67-77. |
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| 作者姓名： | 赵云峰 祝意青 刘芳 徐云马 张国庆 毛经伦 朱辉 |
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| 作者单位： | 中国地震局第二监测中心,陕西西安710054;中国有色金属工业西安勘察设计研究院有限公司,陕西西安710054 |
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| 基金项目： | 地震科技星火计划;国家自然科学基金 |
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| 摘 要： | 本文对2017年以来中国地震局在南北地震带采集到的5期相对重力测网数据进行了平差计算, 简要分析了甘东南研究区内测点平差精度, 进而分析了2019年10月28日甘肃夏河MS5.7地震前的区域重力场变化。 结果表明: ① 研究区内90%测点平差后重力值精度小于10×10-8 m·s-2, 与绝对重力观测结果符合性也较好, 表明观测质量较高, 数据可靠; ② 2017年 4月至2018年4月, 临潭—宕昌断裂南西侧重力正变化、 北东侧重力负变化, 与2017年8月8日九寨沟MS7.0地震前重力变化反向, 断裂西段夏河、 合作附近出现显著的重力差异变化; ③ 2018年4月至2019年4月, 临潭—宕昌断裂南西侧重力变化-10×10-8～-30×10-8 m·s-2、 北东侧重力变化+20×10-8～+30×10-8 m·s-2, 夏河MS5.7震中附近重力变化不明显, 呈现出围绕夏河县、 泽库县和碌曲县等三县交界地区准四象限分布的特征; ④ 强震易发生在重力变化四象限分布中心地带或正、 负异常区过渡的高梯度带上, 九寨沟MS7.0地震后, 我们曾基于流动重力异常变化在夏河MS5.7地震前做过一定程度的中期预测, 尤其是地点预测。
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| 关 键 词： | 2019年夏河Ms5.7地震 重力变化 临潭-宕昌断裂 前兆 |
| 收稿时间： | 2020-02-08 |
| 修稿时间： | 2020-07-31 |
Gravity Changes Before the 2019 Xiahe Gansu Ms5.7 Earthquake |
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| ZHAO Yun-feng,ZHU Yi-qing,LIU Fang,XU Yun-ma,ZHANG Guo-qing,MAO Jing-lun,ZHU Hui.Gravity Changes Before the 2019 Xiahe Gansu Ms5.7 Earthquake[J].Earthquake,2021,41(1):67-77. |
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| Authors: | ZHAO Yun-feng ZHU Yi-qing LIU Fang XU Yun-ma ZHANG Guo-qing MAO Jing-lun ZHU Hui |
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| Institution: | 1. The Second Monitoring and Application Center, China Earthquake Administration, Xi'an 710054, China;
2. Xi'an Engineering Investigation & Design Research Institute of China National Nonferrous Metals Industry CO., LTD. Xi'an 710054, China |
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| Abstract: | The relative gravity data were calculated by the of classic adjustment from 2017 to 2019 in the North-South seismic belt. We analyzed the precision of gravity value at sites in the study area of south-east of Gansu province, and studied the variation of the regional gravity field before Xiahe Gansu MS5.7 earthquake. The results show that ① Gravity value precision of 90% gravity sites is less than 10×10-8 m·s-2 after adjustment calculation in our study area, and the gravity value at absolute gravity sites is well accordance with absolute gravity observation. ② Between April 2017 and April 2018, gravity variation is positive in the south-west side of the Lintan-Dangchang fault, and it is negative in the north-east side of the fault. It is opposite to the gravity variation before Jiuzhaigou MS7.0 on August 8, 2017. There are violent difference gravity variation in the area near the Hezuo city and Xiahe county. ③ Between April 2018 and April 2019, gravity variation is negative in the south-west side of the Lintan-Dangchang fault, about -10×10-8～-30×10-8 m·s-2, and it is positive in the north-east side of the fault, about +20×10-8～+30×10-8 m·s-2. The gravity variation is not obvious near the epicenter of Xiahe MS5.7 earthquake, which indicated that the area near epicenter was possible to be in locked during the time. While there is a unconspicuous four quadrant distribution of gravity change centered on the junction of Xiahe county, Luqu county and Zeku county. ④ Strong earthquakes are prone to occur in four quadrant distribution center of gravity change of high gradient belt of positive and negative anomalies. We made a medium-term forecast about Xiahe MS5.7 earthquake based on relative gravity changes, especially forecasting localities of potential earthquake. |
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| Keywords: | 2019 Xiahe MS5 7 earthquake Gravity changes Lintan-Dangchang fault Precursor |
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