JpGU-AGU Joint Meeting 2017

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-SS 地震学

[S-SS16] [JJ] 地殻構造

2017年5月24日(水) 10:45 〜 12:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:青柳 恭平(電力中央研究所)、Gokul Kumar Saha(Indian Institute of Science Education and Research,Pune)

[SSS16-P06] 南西諸島周辺海域の三次元速度構造

*勝山 美奈子1清水 祥四郎1新井 麗1佐藤 伸明1田中 恵介1高橋 成実1,2金田 義行1,3 (1.国立研究開発法人海洋研究開発機構、2.防災科学技術研究所、3.香川大学)

キーワード:3次元速度構造、南西諸島、琉球列島、沈み込み帯

Introduction
This is a part of the project “Comprehensive evaluation of faults information on offshore Japan”, by the Ministry of Education, Culture, Sports, Science and Technology (MEXT). The project consists of three themes, 1) Collecting seismic survey data and building a database of offshore faults, 2) Interpreting distribution of active faults using seismic data collected, and conducting the seismic re-processing by leading-edge seismic technology for the seismic data obtained in previous decades, 3) Building the fault models for a simulation of strong motion and tsunami disaster, based on the interpreted faults.
Our purpose of this study is make a 3D velocity model in the Nansei-Shoto to provide with the support we needs to interpret faults.
The Nansei-Shoto is one of the islands arcs along the West Pacific continental margins (Philippine Sea Plate subducts Eurasian Plate) and has typical topographic features as an islands arc, where marginal seas, volcanic fronts, islands arcs, sedimentary basins and trenches are regularly and zonally aligned toward the Pacific Ocean.

Methods and data
3D velocity model was constructed by seismic data, well data (ex. T-D curve), and ocean bottom seismometer(OBS) refraction survey data which were obtained by a various agencies and private companies. Horizons such as acoustic basment and unconformity were interpreted using reflection seismic sections. Conrad discontinuity and Mohorovicic discontinuity were interpreted on refraction surveys and consulted previous study. Layer structure and velocity model were created on these horizons by calculation using “Decision Space Geoscience”. The bin size of model creation is 1,000m horizontally (in the case of crust, 500m is applied) and 100m vertically, respectively.

Result
We obtain a result that understands geological structure in Nansei-Shoto. So in this session, we will take a discussion concerning structural characteristic based on the 3D velocity model.