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EARTHQUAKE ›› 2020, Vol. 40 ›› Issue (1): 128-139.doi: 10.12196/j.issn.1000-3274.2020.01.010

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

YANG Yan-ming1, GAO Li-xin1, FAN Ye2, LI Hai-qing3, LU Ying-zhe4, GE Gen1   

  1. 1.Earthquake Agency of Inner Mongolia Autonomous Region, Huhhot 010010, China;
    2.China Earthquake Networks Center, Beijing 100045, China;
    3.Huhhot Seismic Station, Inner Mongolia Autonomous Regiong 010030, China;
    4.Manzhouli Seismic Station, Inner Mongolia Autonomous Regiong 021400, China
  • Received:2018-11-17 Online:2020-01-31 Published:2020-01-20

Abstract: 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.

Key words: Geomagnetism, Harmonic wave amplitude ratio, Anomalous characteristics, Ili, Xinjiang

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