Abstract：By using digital observations of watertube tiltmeter 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.
Deng Na ,Liu Bingbing ,Yang Yaowen et al. DETECTING FREE OSCILLATIONS OF THE EARTH BY USING WATERTUBE TILTMETER OBSERVATIONS AT SHUANGYANG STATION[J]. jgg, 2009, 29(增刊): 41-44.
