昆仑山口西地震激发的地球环型振荡

利用中国数字地震台网(CDSN)改造后的7个台站3天的VHE、VHN波形资料,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,提取了2001-11-14昆仑山口西地震激发的0T2～0T40地球环型自由振荡,并与地球初步参考模型(PREM)的理论自由振荡周期进行对比,发现环型振荡振型周期与PREM预测的环型自由振荡周期符合得很好。频率与PREM模型略微不一致的环型振荡振型可以解释为地球介质的横向不均匀性和各向异性所致。因此地球自由振荡信息可用于揭示地球的三维不均匀结构信息或各向异性信息,并可能对区分地幔对流模式(全地幔对流或上地幔对流)有所帮助。

Toroidal Mode of the Earth's Free Oscillation Excited by the Earthquake to the West of the Kunlun Mountain Pass

Information of the earth's free oscillation can be used to infer the layered structure of the earth and focal mechanism of the earthquake which excited the osillation. In this study, according to VHE and VHN data recorded in 3 days by 7 stations of China Digital Seismograph Network (CDSN) for Nov. 14, 2001 earthquake to the west of the Kunlun mountain pass, we extracted toroidal mode of 0T2~0T40 of the earth free oscillation using power spectral density (PSD) estimation. Because the frequency band of seismograph in China digital seismograph network suppress information of solid tide, it is not necessary to remove the solid tide in our process. Our result is nearly consistent with frequency of the modes of preliminary reference earth model (PREM). The inconsistent modes of toroidal free oscillation may be resulted from lateral heterogeneous or/and anisotropic media of the earth. Thus the data of the earth toroidal free oscillation can be used to explore the 3-dimensional structure (density structure, velocity structure) or anisotropy of the earth and help to disclose the convection mode in the whole mantle or in the upper mantle.