利用超导重力数据检测汶川地震激发的球型地球自由振荡

Detecting Spheroidal Modes of Earth’s Free Oscillation Excitated by Wenchuan Earthquake Using Superconducting Gravity Observations

利用Canberra、Matsushiro、Membach和Metsahovi 4个台站2008年5月的超导重力数据对汶川8.0级大地震激发的球型地球自由振荡进行了研究。结果表明,0S0～0S48全部基频振型以及1S4、2S4和3S13个谐频振型与PREM模型的误差在0.02‰～1.93‰,且所有振型的信噪比均大于阈值3,表明本文的计算方法是有效的,计算结果是可信的;0S2、0S3和0S4存在谱线分裂现象,其谱线分裂率R为1.093 40、0.674 30和1.071 00,验证了地球自转和椭率是引起0S2、0S3和0S4谱线分裂的主要原因。

Spheroidal modes of Earth＇s free oscillation excitated by Wenchuan Ms8.0 earthquake are detected by superconducting gravity observations of Canberra,Matsushiro,MembachandMetsahovi in may, 2008. Results show that the errors of oSoto 0S48,1S4,zS4 and 3S1 are between 0.02% and 1.93%. compared with the PREM model, and their signal-to-noise ratios are all bigger than 3. It is shown that the calculation methods are effective and the calculation results are credible. The spectral splittings of the 0S2,0S3 and oS4 are observed, and their ratios are 1.09340,0.67430 and 1.07100. It is proved that Earth＇s rotation and ellipticity are taken as main reasons of the spectral splittings.