【摘要】 用宜昌台DZW微伽重力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重力潮汐和气压改正的情况下,准确获得了2004年12月26日发生的苏门答腊大地震激发的0S3~0S37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、0S50、S60、S10振型的观测周期和PREM模型理论周期的相对误差大于0.2%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。更多还原

【Abstract】 By use of the digitiled observations of the DZW microgal gravimeter at Yichang station without the corections of gravity tide and prossure the spherical free oscillations of the baseband 0S3-0S37 excited by the 26 Dec.2004 Sumatra earthquake are exactly obtained with the method of power spectrum density estimation.After comparing it with the periods of the theoretical free oscillation calculated with the PREM model it is found out that the observed period coincides with the theoretical.Except for the 0S3,0S4,0S5,0S6 and 0S10 that their relative error between the observed period and the theoretical ones is more than 0.2%,for the most of the others the relative error is about 1%.更多还原