中国数字地震台网记录的苏门答腊—安达曼地震激发的地球球型自由振荡的检测  

SPHEROIDAL OSCILLATIONS OF THE EARTH STIMULATED BY THE SUMATRA-ANDAMAN EARTHQUAKE WITH CDSN DATA

作　　者：万永革[1,2] 盛书中[1] 周公威[1] 郭燕平[1] 尚丹[3] 

机构地区：[1]中国地震局地球物理研究所 [2]防灾科技学院,中国河北065201 [3]防灾科技学院

出　　处：《地震学报》2007年第4期369-381,共13页Acta Seismologica Sinica

基　　金：国家重点基础研究发展规划项目(2001CB711005);国家自然科学基金(40374012)资助.

摘　　要：利用中国数字地震台网（CDSN）改造后的7个台站的VHZ波形资料，提取了2004年12月26日苏门答腊-安达曼地震激发的0S2～0S54地球球型自由振荡，并与地球初步参考模型（PREM）的理论自由振荡频率进行了对比，发现与PREM模型预测的球型自由振荡周期符合得很好．观测的该地震激发的0S2，0S3，0S4，2S1和1S2振型自由振荡有明显的频谱分裂现象．特别是2S1振型，是继Rosat等之后的第二次报道不叠加的情况下观测到的这种振型．根据该地震的总体震源机制，试算了不同的地震矩，模拟了该地震0S2振型在CDSN7个台上的自由振荡振幅，并与记录资料进行了比较。得到该地震的地震矩可达10^23 N·m；本文发现地球自由振荡记录包含了大量震源机制和地震位置的信息，可用于地震震源破裂参数的精细研究．The 0S2 -0S54 spheroidal modes of Earth＇s free oscillations, triggered by the great Sumatra-Andaman earthquake of 26 December 2004 are retrieved from VHZ data recorded by seven upgraded stations of China Digital Seismograph Network （CDSN）. We compare these spheroidal modes with theoretical free oscillation spectra calculated from the Preliminary Reference Earth Model （PREM） and find a coincidence between their periods. Spectral splitting phenomenon is observed obviously in 0 S2, 0 S3, 0 S4, 2 S1 and 1S2 free oscillation modes. What is most noticeable is that the oscillation mode 2 S1 is reported for the second time （the first time by Rosat et al） without any data stacking. We simulated the split singlet of 0S2 mode on seven CDSN stations based on general focal mechanism and seismic moment of the earthquake. The result shows that seismic moment of the earthquake can reach 10^23 N ·m. We also find that the recording of Earth＇s free oscillations carries abundant information of source mechanism and earthquake location, which is applicable to the detailed study of source rupture parameters.

关 键 词：中国数字地震台网 苏门答腊-安达曼地震 地球自由振荡 球型振荡 

分 类 号：P315.3[天文地球—地震学]