[SSS04-P22] Estimated seismic tremor energy for small amplitude tremors
Keywords:slow earthquake, seismic energy
Here, we apply the modified frequency scanning method (mFSM) at a single station to NIED Hi-net data in the southwestern Japan. The original frequency scanning method [Sit et al., 2012] proposed a tremor detection method of calculating envelope waveform ratios through different bandpass filters of broadband data in the Cascadia margin. We modified this analysis for short period seismic Hi-net data recorded in the Southwest Japan. Three bandpass filters of 2–8 Hz, 10–40 Hz, and 0.25–1.0 Hz, corresponding to the dominant frequency band of tremors, local earthquakes, and seasonal noise, respectively. In addition, we removed the regular earthquake events by considering these envelope waveform shapes are similar to exponential curve in 2–8Hz band. We do not use three minutes continuous seismic data when correlation coefficient value is greater than 0.8 between envelope waveform and given simple exponential function.
Our results with mFSM is corresponded to those with multiple method in Southwest Japan. On the other hand, our results include small amplitude tremors which can not be detected with multiple methods. We also estimated their seismic tremor energy including small amplitude tremors which were detected by mFSM at each sites. Amplitudes observed at each site was corrected using the site amplification factors estimated with the coda normalization method and the Euclidean distance between the tremor source and the station, The estimated energy in this analysis may indicates more realistic strain release rate around the plate boundary.