Development of Fundamental Technologies for Mobile and Multi-Station Gravity Gradient Observations

2023 Fiscal Year Final Research Report

• Project/Area Number: 18K04653
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 25030:Disaster prevention engineering-related
• Research Institution: Gunma University
• Principal Investigator: SHIOMI Sachie 群馬大学, 大学院理工学府, 助教 (60584266)
• Project Period (FY): 2018-04-01 – 2024-03-31
• Keywords: 重力勾配 / 干渉計 / 自由落下 / 地下探査 / マッピング

Outline of Final Research Achievements

It is necessary to observe underground structures in detail to improve the accuracy of predicting disasters such as earthquakes, volcanoes, landslides, and road collapses. However, conventional observation methods are affected by various factors, such as ground vibrations, electromagnetic noise, geology, and topography. These factors make them difficult to perform high-precision observations in areas where disaster predictions are needed, such as urban areas and volcanic areas. To solve these problems, we have considered field observation using laser-interferometric gravity gradiometers (LIGGs). Using an interferometer, the LIGGs directly measure the difference in the free-fall acceleration of two test masses. Therefore, the measured values are not affected by anything other than gravity, allowing possible high-precision observations in the field. In this research, we have worked on the development of technologies to realise mobile and multi-station gravity gradient observations.

Free Research Field

重力物理学実験

Academic Significance and Societal Importance of the Research Achievements

従来の手法は前述の通り地形や地質、地面振動や電磁ノイズなどの影響を受けるため、実地での高精度観測が困難であった。干渉計型重力勾配計は、重力以外の影響を受けないことから、地形や地質、地面振動や電磁ノイズの影響を受けることなく、干渉計本来の精度を活かした測定が可能である。また時間分解能も高く、1秒間に5回以上の測定を行うことができる。そのため、実地での移動観測が可能になれば、これまでになく高精度で地下の物質分布に起因する重力勾配を測定できる。また複数台で同時連続観測を行うことで、地下の物質分布の変動を面的に捉えることができる。これらの観測データにより災害予測精度を向上できる可能性がある。