Wavelet filter analysis of splitting and coupling of seismic normal modes below 1.5 mHz with superconducting gravimeter records after the December 26, 2004 Sumatra earthquake

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• 作者：Xiaogang Hu (1) (2)
  Lintao Liu (1)
  Heping Sun (1)
  Houze Xu (1)
  Jacques Hinderer (3)
  Xiaoping Ke (1) (2)
  
• 关键词：superconducting gravimeter ; Sumatra earthquake ; wavelet filter ; Earth free oscillations ; pressure correction
• 刊名：Science China Earth Sciences
• 出版年：2006
• 出版时间：December 2006
• 年：2006
• 卷：49
• 期：12
• 页码：1259-1269
• 全文大小：1750KB
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• 作者单位：Xiaogang Hu (1) (2)
  Lintao Liu (1)
  Heping Sun (1)
  Houze Xu (1)
  Jacques Hinderer (3)
  Xiaoping Ke (1) (2)
  
  1. Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan, 430077, China
  2. Graduate University of Chinese Academy of Sciences, Beijing, 100049, China
  3. Institut de Physique du Globe de Strasbourg (UMR 7516 CNRS-ULP), 5 rue Descartes, 67084, Strasbourg Cedex, France
  
• ISSN：1869-1897

文摘

New generation superconducting gravimeters (SGs), which have been demonstrated to be better than the best seismometers STS-1 at frequencies below 1 mHz, can be accepted as the quietest vertical seismometers for observation of long-period earth free oscillations. Wavelet filtering with narrow band-pass frequency response as shown in this paper is very helpful in removing atmospheric pressure effects from on gravity records in long-period seismic mode frequency bands. The processing of high quality SG records after the great Sumatra earthquake (Dec. 26, 2004) with wavelet filtering leads to clear observations of all coupled toroidal modes below 1.5 mHz except these for 0T5, 0T7 and 1T1; moreover 1T2 and 1T3 are, for the first time, unambiguously revealed in the vertical components of the free oscillations. The three well-resolved splitting singlets of overtones 2S1 are observed from a single SG record for the first time.