利用重力资料监测日本9.0级大震激发的球型自由振荡

DETECTING THE FREE OSCILLATIONS OF THE EARTH EXCITED BY THE JAPAN M9.0 EARTHQUAKE USING OF GRAVITY OBSERVATIONS OF NANSHAN SEISMIC STATION

利用攀枝花南山地震台重力观测资料,检测了2011年日本9.0级大地震激发的0S0～0S39之间基频球型自由振荡,其中有0S0、0S11、0S13、0S22、0S23、0S30、0S35等7个振型观测频率与理论值偏差近似为0,0S2、0S32、0S38、0S39振型频谱不突出,观测效果不明显。观测值与理论值整体平均偏差约为0.10%,观测效果较好,说明了PREM模型理论的正确性,肯定了南山地震台重力资料质量的优良。

By using the digital observations of gravimeter at Nanshan Seismic Station,we extracted 39 spherical modes of0S0～0S39of the earth＇s free oscillation excited by the Japan M9. 0 earthquake in 2011. The deviations between0S0、0S11、0S13、0S22、0S23、0S30、0S35and their theoretical values are almost zero,however,it is difficult to identify the mode of0S2、0S32、0S38、0S39because they are drowned in the noises. The whole mean deviation is about 0. 10%,which can show that there is a good agreement between observed and theoretical values.Such findings mean that the excellent gravity data quality of Nanshan Seismic Station,as well as the validity of PREM model.