甘东南地球物理场异常与夏河MS5.7地震关系分析
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地震科技星火计划项目(XH21033);甘肃省地震局地震科技野外站基金(2021Y11)


Relationship between geophysical anomalies in the southeastern Gansu and the Xiahe MS5.7 earthquake
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    摘要:

    基于甘东南地区2019年地球物理场年度异常,对该区域的地球物理定点观测资料进行全时空扫描,9个台站18个台项在夏河MS5.7地震前出现异常变化。从异常的重复性、多学科前兆的协调性、异常的时空演化及震后异常变化4个方面对各个异常进行信度划分,并根据划分结果定量计算了各个异常与夏河地震关系的信度值。结果显示:18项异常的信度都在50%以上,表明作为夏河地震的前兆异常基本可信,但异常信度存在差异,其中临夏水位、临夏钻孔应变NS向和武都两水水位的信度最高,达到80%,临夏水温和天水钻孔应变NS、NW向的信度最低,低于60%。空间分布上,分布在光盖山—迭山断裂的异常信度较高,而位于西秦岭北缘断裂北侧的异常信度较低,这与该地区构造应力的集中和孕震机制有关。地球物理异常信度分析对建立有效的地震预报指标体系具有很好的促进意义。

    Abstract:

    Combined with the annual geophysical anomalies in 2019, the geophysical fixed-point observation data in the southeastern region of Gansu Province were processed by temporal and spacial scanning, and it was found that eighteen items in nine monitoring stations experienced abnormal changes before the Xiahe MS5.7 earthquake. The reliability of these anomalies were divided from four aspects:the repeatability of anomaly, the coordination of multidisciplinary precursors, the temporal and spatial evolution of anomaly, and the change of anomaly after the earthquake. The reliability value of each anomaly related to the Xiahe earthquake was calculated according to the division results. The calculated results showed that the reliability of each anomaly is more than 50%, indicating that they are basically credible as precursory anomalies of the Xiahe earthquake. Among them, the reliability values of Linxia water level, Linxia borehole strain in the NS direction, and Liangshui water level in Wudu are the highest, up to 80%; the reliability values of Linxia water temperature and Tianshui borehole strain in NS and NW directions are the lowest, less than 60%. The reliability values of anomalies along the Guanggaishan-Dieshan fault are higher than those in the north side of the northern margin fault of the West Qinling, which is related to the concentration of tectonic stress and seismogenic mechanism in the area. The reliability analysis of geophysical anomalies is of great significance to establish an effective earthquake prediction index system.

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苏鹤军,曹玲玲,范兵,李晨桦,周慧玲,马东正.甘东南地球物理场异常与夏河MS5.7地震关系分析[J].地震工程学报,2021,43(6):1269-1279. SU Hejun, CAO Lingling, FAN Bing, LI Chenhua, ZHOU Huiling, MA Dongzheng. Relationship between geophysical anomalies in the southeastern Gansu and the Xiahe MS5.7 earthquake[J]. China Earthquake Engineering Journal,2021,43(6):1269-1279.

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  • 收稿日期:2020-05-25
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  • 在线发布日期: 2021-12-07