Comparison of Spherical Earth Free Oscillation Recorded by Gravimeter and Ultra Broadband Seismometer in Quanzhou Station

In this contribution, we calculated the Earth’s free oscillation stimulated by two earthquakes: the deep-source earthquake of level M_S8.1 occurring in Fiji Islands on August 19, 2018, and the shallow-source earthquake of level M_S8.0 taking place in New Zealand on November 13, 2016. The information of the two earthquakes was recorded by the g-Phone gravimeter and the M2166 ultra broadband seismometer from Quanzhou Station. The results are shown to match the theoretical values quite well. The slight deviations are mostly likely resulted from both the Earth’s lateral heterogeneity and the characteristics of the instrument in the low frequency range. At the same time, it is demonstrated that the harmonic frequency is recorded more clearly for deep-source earthquakes than it is for shallow-source earthquakes; and vice versa for the record of mode shape greater than ₀S₄₀.