采用功率谱方法提取地球自由振荡信息

Earth Free Oscillation Mode Extracted by Power Spectrum Density Method

利用中国数字地震台网的三个台站所记录到的2011年日本里氏9.0级地震的地震数据,在没有进行去固体潮的前提下进行功率谱分析,获得了地球球型自由振荡振型,通过与PREM模型相对比,发现所提取的94个振型,包括76个基频振型(0S0,2S0～0S76)和18个谐频振型,与理论值的误差很小,所有数据的平均偏差为0.14%。文中发现该地震激发的0S2,0S3,0S4和1S2自由振荡振型有明显的频谱分裂现象。

An M9.0 earthquake struck Japan on March 11,2011 and the strong earthquake made continuous oscillation of the earth.Using the 5-day seismic waveform data recorded by China Digital Seismograph Network（CDSN） after the earthquake,we studied the data of VHZ channel by power spectral density estimation.We extracted 76 spherical modes of（0S0,0S2~0S76） of the earth＇s free oscillation and other 18 modes and they are consistent and nearly same with the frequencies of the modes of Preliminary Reference Earth Model（PREM）.Spectral split ting phenomenon is observed obviously in 0 S2,0 S3,0 S4 and 1 S2 free oscillation modes.