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Title:: Oscillation Analysis of GPS Horizontal Time Series before the Wenchuan Earthquake

Author(s):: FANG Ying; JIANG Zai-sen; GU Guo-hua; (Institute of Earthquake Science,CEA,Beijing 100036,China)

摘要:: 采用复小波分析技术,分析了中国大陆GPS基准站水平向时间序列的多时间尺度和周期性变化特征。结果表明,青藏高原GPS站的南北分量在2007年初至汶川大地震发生前,出现一个周期的准同步周年振荡异常,且向北方向的半周期波峰振幅明显高于各点在印尼苏门答腊巨震后大尺度北东向长趋势运动的加速度,这可能是导致龙门山闭锁段破裂的重要触发因子。这种振荡的周期集中在汶川大地震前355～375天,与地球绕太阳公转周期非常一致。

Abstract:: The article analyzed multi-time scale characteristics and seasonal changes of horizontal time series of GPS fiducial stations in Mainland China by complex wavelet analysis techniques.The results showed that,from early 2007 to the Wenchuan earthquake,a quasi-synchronous annual cycle abnormal oscillation occurred in north-south components in GPS stations of Tibet Plateau.The northward amplitudes were significantly higher than their accelerations of large-scale trends in north-east movement after the great Sumatra earthquake in Indonesia.The phenomenon was explained as follows.The great Sumatra earthquake in Indonesia might be an important trigger factor leading to the breakdown of Longmenshan locked segments.This cycle of Oscillation before the Wenchuan earthquake concentrated in between 355 days and 375 days(with the earth around the sun very consistent cycle),leading to the reasons for this change is unclear,pending further in-depth study.