新疆伊犁及邻区地磁谐波振幅比异常特征分析

Analysis on the Anomalous Variation Characteristics of Geomagnetic Harmonic Wave Amplitude Ratios in Ili, Xinjiang and Surrounding Regions

本文利用新疆伊犁及邻区温泉和克拉玛依红浅两个地磁台站2008年至2015年FHD分钟值观测数据,采用地磁谐波振幅比计算方法,选取台站300 km范围区域内,震级M≥5.0的震例进行映震效果分析。结果表明,M5.0以上地震发生前后,温泉和克拉玛依红浅台站的地磁谐波振幅比异常变化特征主要表现为"下降-转折-恢复上升"。异常持续总时间约为1~3年,地震发生在趋势性下降变化后的转折期或者恢复上升阶段,其中,6.0级地震异常持续总时间为2~3年,震前为1~2年。温泉台谐波振幅比异常存在较为明显的长周期向短周期迁移现象,意味着对应的未来地震震中距一般在100 km以上。温泉和克拉玛依红浅台均发现不同测项之间或者同一测项不同周期之间存在不同步现象,并且地震发生在同步性变差的阶段。

Using the one minute sampling geomagnetic data recorded of FHD between 2008 and 2015 that observed by two geomagnetic stations such as Wenquan and Karamay Hongqian,selecting earthquakes greater than magnitude 5.0 within a distance of about 300 km from above stations,geomagnetic anomalies and its characteristics around the earthquakes are obtained by geomagnetic harmonic wave amplitude ratio method.Moreover,the capacity reflecting earthquakes is evaluated,respectively.Comprehensively analyzing the anomalous variation characteristics in this study lead to the following conclusions.The anomalous variation of geomagnetic harmonic wave amplitude ratios in seismogenic process of moderate-strong earthquake greater than magnitude 5.0 are declining,turning,then resuming,and the duration is about one to three years.Earthquakes typically appeared in the twist or recovery phase after gradual decline in the trend.Besides,the duration for abnormality of earthquake with magnitude around six lasted for two to three years and be about one to two years prior to earthquake.Meanwhile,the migration characteristics of markedly anomalous variation from long-period to short-period are found at Wenquan station.It means distance more than 100 kilometers from the station to the earthquake in the future with which the anomalies are corresponding.There was asynchronization between long period and short period or north-south direction and west-east direction at Wenquan and Karamay Hongqian stations,respectively.And the earthquake occurred in stage during which synchronicity gets worse.