[S07-6] Site effects I

[S07-6-05] Revision of 3D Model of the Kanto Basin based on Earthquake Records of MeSO-net

^○Haruo Yoshida¹, Yoshiyuki Sato¹, Kikuji Kobayashi¹, Naoko Umeda², Shinichi Sakai³, Hirata Naoshi³ (1.Research & Development Institute, Takenaka Corporation, Chiba, Japan, 2.Building Design Department, Tokyo Main Office, Takenaka Corporation, Tokyo, Japan, 3.Earthquake Research Institute, The University of Tokyo, Tokyo, Japan)

In recent years, numerous simulations using 3D finite-difference method are performed to predict earthquake ground motions due to large earthquakes. In order to improve the prediction accuracy of earthquake ground motions, Accuracy of 3D underground structure model is one of the important factors. To obtain a 3D Kanto Basin model, Yoshida et al. (2007) estimated the underground structure under 120 K-NET and KiK-net sites in Kanto Basin by using the method of Kobayashi et al., (2005). In this method the horizontal-to-vertical (H/V) spectral amplitude ratios and receiver functions of P wave part of seismic observation records were simultaneously inversed. Then a 3D model of the Kanto Basin was constructed by spatial interpolation using the estimated underground structures and gravity anomaly data. In order to improve the accuracy of this model, we increased estimation points of underground structure utilizing about 200 sites of MeSO-net (Sakai and Hirata, 2009) which were located at 296 sites in Kanto region, and we also used the improved method of Umeda and Kobayashi (2010) which is added H/V spectral amplitude ratio of coda part of seismic observation records to the method of Kobayashi et al. (2005). Then the model was modified by adding the estimated underground structures. Medium earthquakes occurred below the Kanto Basin were simulated using the revised 3D model to compare the calculated and observed velocity waves. By comparing the simulation results from the original model, the influence of addition of estimated underground structures on the improvement of the prediction accuracy was discussed.