Tectonice Geomorpholy of the coastal area along the Nansei-Shoto islands based on the detailed digital elevation data

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H01374
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 04010:Geography-related
• Research Institution: Hiroshima University
• Principal Investigator: Goto Hideaki 広島大学, 人間社会科学研究科(文), 准教授 (40323183)
• Co-Investigator(Kenkyū-buntansha): 杉戸 信彦 法政大学, 人間環境学部, 教授 (50437076) ; 隈元 崇 岡山大学, 自然科学学域, 教授 (60285096)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 海成段丘 / 海底段丘 / 数値標高モデル / 変動地形 / 活断層

Outline of Final Research Achievements

Late Quaternary tectonic deformation of coastal areas is usually examined using height distribution of paleo-shorelines observed on marine terraces. Shallow-sea features, such as cliffs and terraces, can provide essential information regarding topographical evolution and crustal movement, since the development of submarine topography above -120 m has become relevant for sea-level changes during the last glacial period, including the Last Glacial Maximum. Since the 2000s, digital elevation models surveyed by multi-beam sound systems have been acquired, and tectonic geomorphological studies in coastal areas have substantially progressed. We focused on the widespread shallow submarine terraces exhibited indistinct marine terraces in the middle part of the Nanseishoto Islands. We examined height differences between paleo-shore lines and displacements of the submarine terrace based on the detailed maps.

Free Research Field

地理学

Academic Significance and Societal Importance of the Research Achievements

本研究は，これまで地図の乏しい沿岸海域に注目し，陸海を統合した高精細な地形図・ステレオ画像を作成し，それらを読み解くものである。革新的に詳しい海底地形が調査できるマルチビーム測深によって得られた海底地形データを用いており，地殻変動の乏しい場所や激しい場所で共通性や違いを明らかにした。南西諸島中部では，巨大地震が発生しないと考えられているが，地形学的な時間スケールでは島棚に直交する圧縮歪みが蓄積されていると考えられ，これまでの見解の修正を迫る結果となった。