2016年12月25日智利M7.6地震球型自由振荡检测

智利M7.6的地震激发了地球自由振荡,利用中国数字台网(CDSN)的10个台站记录到7 d的VHZ波形数据,采用功率谱密度估计方法,在没有滤波的情况下,提取了2016年12月25日智利地震激发的地球球型自由振荡基频振型_0S_4～_0S₅₃和一系列的谐频振型,并与PREM模型的理论自由振荡频率峰值进行对比,发现2.5～4.5×10¹³Hz的频率值与PREM模型预测的球型自由振荡周期符合得很好,说明本次地震确实激发了全球范围内的自由振荡,而4.5～6×10¹³ Hz的频率值稍微有偏离,这是由于地壳的横向不均匀所致,可以用来研究地球内部的构造。

Detection of Spherical Free Oscillation of Chile M7.6 earthquake on December 25th,2016

The Chile M7.6 earthquake excited the free oscillation of the earth. By using 7 d VHZ waveform data recorded by 10 stations of Chinese digital network(CDSN)and the power spectral density estimation method,in no case of filtering,the paper extracted the fundamental frequency 0S4~0S53 and a series of harmonious vibration frequency of the free oscillation of the earth vibration excited by the Chile earthquake on December 25th,2016,and compared with the theoretical free oscillation frequency peak value of the PREM model. The results show that the 2.5~4.5×10^13 Hz frequency value of the spherical free oscillation cycle prediction and PREM model are in good agreement. The earthquake does stimulate the global range of free oscillation,and 4.5~6×10^13 Hz frequency value is slightly deviated duing to the horizontal unevenness of the earth's crust,which can be used to study the internal structure of the earth.