[S-TT37] 空中からの地球計測とモニタリング

[STT37-01] ドローンを用いた空中磁気測量による三宅島磁化構造解析

*小山 崇夫¹、金子 隆之¹、大湊 隆雄¹、渡邉 篤志¹、本多 嘉明²、秋山 峻寛¹、田中 伸一¹ (1.東京大学地震研究所、2.千葉大学環境リモートセンシング研究センター)

キーワード：三宅島、ドローン、無人ヘリコプター

Miyakejima volcano had the latest eruption in 2000 with the summit subsidence, and the next event will be expected in the near future. An aeromagnetic survey in Miyakejima was done in March 2021 in order to investigate a current state of he magnetization structure in Miyakejima and find a potential of a possible next eruption for a volcanic disaster mitigation. The survey flight was conducted by using an unpersoned aerial vehicle (UAV), a multirotor drone, deploying a scalar magnetometer. Processing the geomagnetic field data of this survey combining with data of previous surveys conducted by using another UAV, an unpersoned helicopter, an averaged magnetization intensity was found as 12.4 A/m, and a surrounding area of the crater is relatively highly magnetized, but a crater rim has a low magnetization intensity. Temporal variation between 2014 and 2021 was detected and dominated at the central part of the observation area. Decrease of the magnetization intensity was found beneath the caldera, and it may be possible to be recently demagnetized due to heat supply from the deep heat reservoir through fractures in an impermeable layer.