2017年8月8日九寨沟7.0级地震前地磁垂直强度极化短期异常特征分析

doi:10.12196/j.issn.1000-3274.2021.04.005

摘要/Abstract

摘要： 对2017年8月8日九寨沟7.0级地震前后四川及其邻区地磁台站数据进行垂直强度极化方法计算, 使用5~100 s周期发现震前地磁极化计算结果存在如下的显著异常特征: ① 2017年3月震中附近地磁台站同步存在极化超阈值异常, 时间上显示为短期异常; ② 同步异常台站出现最大幅度的时间较一致; ③ 九寨沟地震发生在异常阈值线附近, 对该方法预测地点有一定指示意义; ④ 对比异常时段内的Dst指数, 认为此次同步超阈值异常不是空间电流体系所造成的; ⑤ 3月18日地磁台站出现极化异常的台站数量较多, 异常分布区域面积较大, 异常主要集中在西北地区可能反映了该区域的应力作用。

关键词: 九寨沟地震, 地磁, 频段, 垂直强度极化方法, 异常特征

Abstract: The vertical intensity polarization is calculated by using the geomagnetic data of Sichuan and its adjacent areas before and after the Jiuzhaigou M_S7.0 earthquake on August 8, 2017. The geomagnetic polarization results at 5~100 s frequency band before the earthquake have the following obvious abnormal characteristics: ① In March 2017, the geomagnetic stations near the epicenter synchronously showed polarization over threshold anomalies, which are short-term anomalies in time. ② The occurrence time of the maximum amplitude was consistent for abnormal stations. ③ The Jiuzhaigou earthquake occurred near the anomaly threshold line, which has a certain indication significance for the prediction location of this method. ④ Compared the Dst index in the abnormal period, it is considered that the synchronous anomalies over threshold were not caused by the space current system. ⑤ On March 18, there were more stations with polarization anomalies to cover a larger area, and the anomalies mainly concentrating in Northwest China may illustrate the stress effects in this region.

Key words: Jiuzhaigou earthquake, Geomagnetism, Frequency band, Vertical intensity polarization method, Anomaly characteristics

中图分类号:

P315.7

廖晓峰, 樊文杰, 邱桂兰, 李雪浩, 杨鹏. 2017年8月8日九寨沟7.0级地震前地磁垂直强度极化短期异常特征分析[J]. 地震, 2021, 41(4): 68-77.

LIAO Xiao-feng, FAN Wen-jie, QIU Gui-lan, LI Xue-hao, YANG Peng. Analysis on Short-Term Characteristics of Geomagnetic Vertical Intensity Polarization Anomaly Before Jiuzhaigou 7.0 Earthquake on August 8, 2017[J]. EARTHQUAKE, 2021, 41(4): 68-77.

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