利用双阳台水管观测资料检测地球自由振荡

DETECTING FREE OSCILLATIONS OF THE EARTH BY USING WATER-TUBE TILTMETER OBSERVATIONS AT SHUANGYANG STATION

基于双阳台水管倾斜仪的数字化观测资料,利用功率谱密度估计方法,在没有对资料进行去固体潮处理的情况下,准确获得了2004年12月26日苏门答腊大地震激发的0S3～0S31基频球型自由振荡。并与PREM模型的理论自由振荡周期进行了对比,发现实测振荡周期与PREM预测的振荡周期相吻合,除0S3、0S4振型的观测周期和PREM模型理论周期的相对误差大于0.3%外,其他振型的观测周期和PREM模型理论周期的相对误差大都集中在0.1%左右。同时还检测到了5个谐频球型振荡和8个环型振荡。

By using digital observations of water-tube tihmeter at Shuangyang station and with power spectrum density estimating method, acquire 0S3 -0S31 fundamental sphere free oscillations caused by Sumatra earthquake on 26th Dec, 2004 were obtained, without deleting influence of the earth tide on the data, then we compared it with theoretical free oscillations cycle of PREM model, and found out that the actual measurement cycle is accordant with PREM forecasting oscillations cycle. Besides the difference between the vibration observation cycle of 0S3,0S4 mode and PREM model cycle is more than 0.3%, other differences are about 0.1%. In the same time we detected five harmonic frequency sphere oscillations and eight ring oscillations.