Study on tsunami buffer zone setting considering probabilistic tsunami hazard assessment

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15266
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 25030:Disaster prevention engineering-related
• Research Institution: Kanto Gakuin University
• Principal Investigator: Fukutani Yo 関東学院大学, 理工学部, 准教授 (10785322)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 津波 / ハザードマップ / バッファゾーン / 確率論的津波ハザード評価 / 再現期間 / ハザードの不確実性 / 要避難対象区域

Outline of Final Research Achievements

In the survey on the current status of buffer zone setting, which represents the uncertainty of the expected tsunami inundation area, we investigated cases in coastal municipalities across Japan through interviews and questionnaires. Many municipalities set it up to the boundary of towns outside the expected tsunami inundation area, and others set the buffer zone up to arterial roads or major roads outside the expected tsunami inundation area, a certain elevation, a certain tsunami height, along rivers, past tsunami inundation areas, and distance from the edge of the expected tsunami inundation area. We also developed a new probabilistic hazard assessment method for tsunami inundation area considering the uncertainty of the Sagami Trough megathrust earthquake, using the proper orthogonal decomposition and logic tree approach, and finally obtained tsunami inundation area for each return periods such as 500-years and 1000-years by applying the probability of earthquake occurrence.

Free Research Field

土木工学、海岸工学

Academic Significance and Societal Importance of the Research Achievements

地域住民の津波からの避難を考えるうえで重要となる津波浸水想定区域の不確実性を表すバッファゾーンは、各市町村が津波ハザードマップ作成時に記載できるが、作成基準が無いのが現状である。市町村は、地域の特性に応じた独自の設定基準に加え、本研究で整理した他自治体の例を参考にして設定することが可能となる。また、提案した確率論的津波浸水評価手法を用いることで、再現期間別の津波浸水区域の作成やこれを基にした不確実性を考慮したハザードマップのバッファゾーン設定が可能であり、市町村が要避難対象区域を設定する際の一手法として利用されることが期待できる。