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  

作　　者：Jacques Hinderer 

机构地区：[1]Institut de Physique du Globe de Strasbourg (UMR 7516 CNRS-ULP), 5 rue Descartes, 67084 Strasbourg Cedex, France

出　　处：《Science China Earth Sciences》2006年第12期1259-1269,共11页中国科学（地球科学英文版）

基　　金：This research was jointly supported by the National Natural Science Foundation of China(Grant Nos.40574009 and 40374029);the Hundred Talent Program of the Chinese Academy of Sciences(CAS);the Knowledge Innovation Project of CAS(Grant No.KZCX3-CW-131).

摘　　要：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 at- mospheric 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.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 at- mospheric 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.

关 键 词：SUPERCONDUCTING gravimeter Sumatra earthquake wavelet filter Earth free oscillations pressure correction. 

分 类 号：P315[天文地球—地震学]