Experiment for detection of volcanic fluid movements by gravity gradiometer

2014 Fiscal Year Final Research Report

• Project/Area Number: 24651198
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Natural disaster science
• Research Institution: Kyoto University
• Principal Investigator: KAGIYAMA Tsuneomi 京都大学, 理学(系)研究科(研究院), 教授 (50126025)
• Co-Investigator(Kenkyū-buntansha): SHIOMI Sachie 京都大学, 生存圏研究所, 研究員 (60584266)
• Co-Investigator(Renkei-kenkyūsha): KURODA Kazuaki 東京大学, 宇宙線研究所, 教授 (00242165)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 火山 / 重力勾配 / 自然災害 / 火山噴火 / 測地 / 地下水

Outline of Final Research Achievements

Gravity observation is useful for monitoring volcanic activity, because it gives information on material movement. But it also needs the height of the measuring points. The gravity gradiometer measures differential accelerations between two test masses that are in free fall at different heights, and measured values are insensitive to the change of the observation height. Therefore, the gravity gradiometer could be useful for monitoring of volcanic activity. According to the gravity measurements in Aso volcano, the change in gravity exceeds 60 µGal around the crater, and this change indicates hydrothermal mass movement. The prototype gravity gradiometer was applied Aso and Sakurajima volcanoes. Unexplained disturbances were observed in longer term measurements, and after understanding the sources of the disturbances, vertical gravity gradients was succeeded to observe within a few μGal/m error. However, this gradiometer has many difficulties to apply volcanic fields.

Free Research Field

火山物理学