Tectonic geomorphology of coastal area along the Ryukyu Arc based on the topographic anaglyphs from detailed digital elevation models covering Inland and Seafloor

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K01221
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Geography
• Research Institution: Hiroshima University
• Principal Investigator: Goto Hideaki 広島大学, 文学研究科, 准教授 (40323183)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 変動地形学 / 海成段丘 / 数値標高モデル / 海底地形 / 海底活断層 / 地形アナグリフ

Outline of Final Research Achievements

Topographic anaglyph images were viewed with red-cyan glasses, making it possible to recognize topographic relief features readily. Anaglyphs produced from digital elevation model (DEM) data are a very effective way of identifying tectonic geomorphology. This study aims to re-examine tectonic geomorphology and to present new tectonic maps for the late Quaternary of the coastal area along the Nanseishoto islands, based on the interpretation of the topographic anaglyph derived from the digital surface model (DSM) of inland as well as the DEM of the seafloor.
Late Quaternary tectonic geomorphology in and around Yoron island like the NNW-SSE trending left-lateral strike-slip fault as well as the surface deformation associated with the arc-parallel anticline is estimated to be formed under E-W to WNW-ESE trending compressive stress field. This stress field would be related to the subduction of the Philippine Sea plate beneath Eurasian plate along the Nanseisyoto trench.

Free Research Field

地理学

Academic Significance and Societal Importance of the Research Achievements

南西諸島周辺はその西側にある沖縄トラフを形成する伸張性の活動が卓越すると広く信じられてきたが，南西諸島周辺から南西諸島海溝にかけては，圧縮性の逆断層や横ずれ断層による変動地形が海陸ともに顕著であることが明らかとなった。数万～数千年スケールでは南西諸島海溝に沿った沈み込みの営力が諸島付近まで蓄積していることを示し，発生しないとされている海溝に沿った巨大地震の発生について，検討の必要性を迫る成果といえる。