【摘要】 利用云南省数字化水管仪的观测资料,采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0S4～0S30基频球型自由振荡,并与前人的观测结果进行比较,同时对照了PREM模型的理论计算周期,发现水管仪观测与这三者符合得非常好,除0S4振型的观测周期和周期1、周期2、周期3的相对误差均大于0.3%外,其余的差别在3‰以下。研究表明,利用数字化水管仪观测资料的确可以提取到苏门答腊大地震激发的地球球型振荡,这就为地球自由振荡的研究提供了一种新的观测手段。更多还原

【Abstract】 By power spectrum density estimation,we extract the fundamental-frequency,spheroidal,free oscillation(0S3～0S26)of the Earth excited by the M9.0 Sumatra-Andaman great earthquake on 26 December 2004 from the data of digital water-tube tiltmeters from Yunlong seismic station,Yongsheng seismic station,and Chuxiong seismic station in Yunnan Province without eliminating the Earth’s tide.Comparing the extracted free oscillation with those observed by Benioff with the strainmeter Isabella and by Ness with the gravimeter Lacoste-Romberg and referring to the period of the extracted oscillation with that of the theoretical oscillation from the Preliminary Reference Earth Model(PREM),we find that they are in very good accordance with each other;the relative errors of 0S4 period,period 1,period 2,period 3 are greater than 0.3% while the relative errors of other periods are less than 3‰.This proves that extracting the free oscillation of the Earth from the data of digital water tube tiltmeter is a new approach.更多还原