地震研究

采用成都台和天水台GM4磁通门磁力仪秒采样地磁数据,计算得到这2个台站的20～230 s周期的谐波振幅比,发现该周期范围内的谐波振幅比在地震前出现的异常与10～60 min周期的谐波振幅比类似,主要表现为下降—转折—恢复上升的变化形态。成都台的谐波振幅比异常呈现南北方向和长短周期均不同步的特征,而天水台只有长短周期之间出现不同步现象。根据异常特征推测天水台位于岷县—漳县6.6级地震前的高导体区域内,而成都台则位于芦山7.0级地震前的高导体东侧边界附近。

This paper calculates the geomagnetic harmonic wave amplitude ratio with periods of 20～230 s by using the data of GM4 fluxgate magnetometer at the Chengdu station and Tianshui station.We find that the abnormal variations of geomagnetic harmonic wave amplitude ratio with periods of 20～230 s showed the characteristics of down-turning-recovery before earthquakes,which were same as the abnormal variations of geomagnetic harmonic wave amplitude ratio with periods of 10～60 min.At the Chengdu station,there was asynchronization between north-south direction and west-east direction,and also between long-period and short-period.However,the asynchronous phenomenon at the Tianshui station only existed between long-period and short-period.According to the anomaly characteristics,we infer that the Tianshui station was located in the high conductive body before the Minxian-Zhangxian M6.6 earthquake,and the Chengdu station located near the east border of the high conductive body before the Lushan M7.0 earthquake.

引言
1 分析方法和计算过程
2 计算结果和异常特征
3 讨论
4 结论

图1 台站与震中分布<br/>Fig.1 Distribution of seismic stations and earthquake epicenters used in the study

图1 台站与震中分布
Fig.1 Distribution of seismic stations and earthquake epicenters used in the study

图2 芦山7.0级地震前成都台南北向(a)、东西向(b)20～230 s周期的谐波振幅比<br/>Fig.2 The geomagnetic harmonic wave amplitude ratio of NS(a)and EW(b)at the pericd of 20～230 s at the Chengdu station before the Lushan MS7.0 earthquake

图2 芦山7.0级地震前成都台南北向(a)、东西向(b)20～230 s周期的谐波振幅比
Fig.2 The geomagnetic harmonic wave amplitude ratio of NS(a)and EW(b)at the pericd of 20～230 s at the Chengdu station before the Lushan MS7.0 earthquake

表1 成都台谐波振幅比异常参数<br/>Tab.1 The abnormal parameters of harmonic wave amplitude ratio at the Chengdu station

表1 成都台谐波振幅比异常参数
Tab.1 The abnormal parameters of harmonic wave amplitude ratio at the Chengdu station

图3 岷县—漳县6.6级地震前天水台南北向(a)、东西向(b)20～230 s周期的谐波振幅比<br/>Fig.3 The geomagnetic harmonic wave amplitude ratio of NS(a)and EW(b)in the pericd of 20～230 s at the Tianshui station before the Minxian-Zhangxian MS6.6 earthquake

图3 岷县—漳县6.6级地震前天水台南北向(a)、东西向(b)20～230 s周期的谐波振幅比
Fig.3 The geomagnetic harmonic wave amplitude ratio of NS(a)and EW(b)in the pericd of 20～230 s at the Tianshui station before the Minxian-Zhangxian MS6.6 earthquake

表2 天水台谐波振幅比异常参数<br/>Tab.2 The abnormal parameters of harmonic wave amplitude ratio at the Tianshui station

表2 天水台谐波振幅比异常参数
Tab.2 The abnormal parameters of harmonic wave amplitude ratio at the Tianshui station

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备注

引言

1 分析方法和计算过程

2 计算结果和异常特征

3 讨论

4 结论

期刊信息