基于分层结构参数变化的地球自由振荡简正模研究

大地震激发导致的地球自由振荡可为获得地球深部结构提供重要手段,通过理论计算自由振荡简正模的本征周期,并与实测结果进行比较,可为地球深内部结构和新地球模型的研究提供有效约束.采用微分方程数值积分技术和G-D1066A地球模型,本文计算了0~48阶的187个球型自由振荡简正模的本征周期,将计算结果与Gilbertt和Dziewonski等3组模型理论结果及Ness等4组观测结果进行比较,相对偏差在0.3%以内.分析说明由于考虑了地幔、外核和内核等不同分层密度和拉梅参数变化的影响,获得了较高精度的地球自由振荡简正模周期.本文提供的理论计算结果可为修正真实地球内部参数提供有效参考.

Study of normal mode based on the changes of stratified structure parameters

The research of Earth′s free oscillations generated by large earthquakes gives important support to the study of Earth′s deep internal structure. By comparing calculated normal mode eigenperiods with observations can offer an efficient constraint in the research of Earth′s internal structure and new earth model. Using numerical integration method and Earth model G-D1066A, we obtain 187 eigenperiods between angular order 0 and 48. The relative errors between our results and previous three theoretical or four observed results are under 0.3%. The analysis shows that because the effects of density and Lame′s parameters in different layers of Earth′s interior are considered, the eigenperiods we obtained have good precision. The theoretical results given in this paper can give effective reference for revising the parameters of real Earth′s interior.