中国数字地震台网记录的2014年10月14日M7.3萨尔瓦多地震地球球型自由振荡研究

Study on Spherical Earth Free Oscillation Excited by the Salvador M7.3 Earthquake on October 14^(th), 2014 Recorded by China Digital Seismograph Network(CDSN)

萨尔瓦多M7.3地震激发了地球的自由振荡,利用中国数字地震台网(CDSN)10个台站记录到震后4 d的数据资料,采用功率谱密度估计方法提取到该地震激发的地球球型自由振荡基频振型0S4~0S64,并与PREM模型的理论自由振荡频率峰值进行了对比。结果显示:1.5×10^(-3)~5.0×10^(-3) Hz观测频率值与PREM模型理论频率值较相符,证明本次地震确实激发了全球范围内的自由振荡,而0.6×10^(-3)~1.5×10^(-3) Hz和5.0×10^(-3)~7.0×10^(-3) Hz与理论频率值略微偏离的,可以解释为地壳的横向不均匀所致。对采用地球自由振荡振型资料进一步约束地球模型和地震震源参数提供了依据。

By using the 4 days post-earthquake waveform data recorded by 10 stations of the China Digital Seismograph Network（ CDSN） excited by the Salvador earthquake, the paper retrieved the frequency of the fundamental model 0S40S64 of the spherical free oscillation by the method of power spectral density estimation,and compared the peak frequencies with the theoretical frequencies of the PREM model. The results show that：the estimated power spectral density in the range of 1.5×10-3-5.0×10-3Hz is exactly consistent with the theoretical frequency value predicted by PREM model; the discrete peak values of power spectral density in the range of 0.6×10-3-1.5×10-3Hz and 5.0×10-3-7.0×10-3Hz are slightly deviated from the theoretical values, which can be interpreted as the horizontal homogeneity of the crust. The results can be used to constrain the earth model and seismic source parameters in further studies.