Conditions for generating tsunami-induced turbidity currents and their depositional processes: Examination of a new generating mechanism of turbidity currents

2017 Fiscal Year Final Research Report

• Project/Area Number: 26287127
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Geology
• Research Institution: Kyoto University
• Principal Investigator: Naruse Hajime 京都大学, 理学研究科, 准教授 (40362438)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 津波 / 混濁流 / 堆積相解析 / モーフォダイナミクス / 逆解析 / 災害 / 海洋地質 / タービダイト

Outline of Final Research Achievements

Firstly, as a result of numerical experiments, it was suggested that there are distinct threshold conditions to generate turbidity currents from tsunamis. Turbidity currents can be developed from very dilute suspended clouds due to the self-acceleration mechanism if initial height of clouds are sufficiently high. On the other hand, when the initial conditions are slightly below the threshold condition, turbidity current decays very rapidly. This suggests that only large-scale tsunamis like 2011 Tohoku-Oki Tsunami can produce turbidity currents.
Secondly, the inverse modeling of turbidites proposed in this study enables us to estimate the flow conditions from thickness and grain-size distributions of turbidites that are measured at every ca. 1 km along flow directions. This method will be useful for future investigation of past-tsunami records using tsunami-generated turbidites.

Free Research Field

堆積学