Development of a new evaluation method for fumarolic activities in active volcanoes with interferometric SAR analysis

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K04005
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: Hirosaki University (2023); Hot Springs Research Institute of Kanagawa Prefecture (2019-2022)
• Principal Investigator: Doke Ryosuke 弘前大学, 理工学研究科, 准教授 (00604109)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: 干渉SAR解析 / 箱根火山 / 水蒸気噴火 / 熱水系 / 地すべり

Outline of Final Research Achievements

In this study, the structure that characterizes the shallow hydrothermal system of Hakone volcano as a field where phreatic eruptions are occurred is clarified from the results of interferometric SAR analysis. Based on a model of underground pressure sources estimated from surface displacement revealed by interferometric SAR analysis, the shallow hydrothermal system of Hakone volcano is characterized by pocket- shaped fluid reservoirs and northwest-southeast striking cracks as fluid supply paths to the reservoirs. We also found that the volcano has been contracting since the 2015 phreatic eruption, and that landslide displacement has been observed. All of these phenomena are considered to be caused by the hydrothermal activity of the volcano.

Free Research Field

固体地球科学

Academic Significance and Societal Importance of the Research Achievements

水蒸気噴火はその活動の規模が小さく，観測事例が少ないため，その活動の予測などが困難な現象である．本研究では，2015年に水蒸気噴火が発生した箱根火山を対象に，干渉SAR解析を多数実施することにより，水蒸気噴火前や，噴火後の地表面変位の推移を明らかにした．これにより，水蒸気噴火を発生させる場としての箱根火山の浅部熱水系を特徴づける構造について明らかにすることができた．この特徴は，過去に同火山で発生した水蒸気噴火や周辺地域における地殻変動などとも関連があることが示され，本研究成果により，箱根火山を含む同地域の防災を考える上での基礎的なデータを得ることができたと言える．