日本地球惑星科学連合2018年大会

講演情報

[JJ] ポスター発表

セッション記号 S (固体地球科学) » S-CG 固体地球科学複合領域・一般

[S-CG66] 3次元地質モデリングとシミュレーションの新展開

2018年5月22日(火) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:高野 修(石油資源開発株式会社技術研究所)、木村 克己(独立行政法人防災科学技術研究所)

[SCG66-P03] Construction of 3D sedimentary velocity structure model of Nara Basin

*関口 春子1浅野 公之1岩田 知孝1 (1.京都大学防災研究所)

キーワード:堆積盆地、速度構造、奈良盆地

We constructed a 3D sedimentary velocity structure model of the Nara Basin, Japan, combining geological knowledge, geophysical surveys, and seismological observations to contribute to the improvement of ground motion prediction for future earthquakes. Not many geophysical surveys have been conducted on the underground structure in the Nara Basin. However, geological studies suggest that the sediment filling the Nara basin and the Osaka basin have common ground. Therefore, we utilized the methods and knowledge we acquired through modeling the velocity structure of the Osaka basin to construct a sedimentary velocity structure model of the Nara Basin. Firstly, a key beds’ depth model was constructed by combining the bedrock-depth distribution estimated from gravity anomaly and the geological profile at a borehole near the center of the Nara Basin. Then, the key beds’ depth model, meaning the 3D structure of the depositional age, was converted to a 3D structure model of seismic velocities and density. Microtremor observation results were used to constrain the 3D sedimentary velocity structure model in terms of the seismological response of the ground. The ability of the sedimentary velocity structure model to reproduce ground motion was examined through a ground motion simulation for a small earthquake.