[SSS11-P08] Estimation of scattering coefficient and intrinsic absorption in the Chugoku district (2)
Keywords:seismic wave energy, scattering, intrinsic absorption
In this study, we improved the coda normalization process for correcting the source and site effects in the method of Sasaki et al. Though they assumed that the scattering coefficient (g0) and intrinsic absorption (Qi-1) are uniform, we introduced a model such that the crust and the uppermost mantle could have g0 and Qi-1 of different values. We analyzed the Hi-net data of the same events using the improved method. We obtained the g0 and Qi-1 for frequency bands of 1-2, 2-4, and 4-8 Hz. The g0 did not show obvious frequency dependence, but the Qi-1 appeared smaller for higher frequencies. The g0 values we estimated were significantly smaller than those estimated by the previous studies using the MLTW method for all frequency bands. The choice of g0 and Qi-1 of the uppermost mantle gave little influence on the results. This is because the ray paths from the shallow events (9-13km in depth) that we selected mostly go through the crust only. To evaluate the g0 and Qi-1 of the uppermost mantle, we would need to analyze data of deeper events.
Acknowledgements: We used the data by the Hi-net and the dataset of the velocity structure model of Matsubara and Obara (2011), both provided by National Research Institute for Earth Science and Disaster Resilience.