JpGU-AGU Joint Meeting 2017

講演情報

[EJ] ポスター発表

セッション記号 S (固体地球科学) » S-TT 計測技術・研究手法

[S-TT58] [EJ] 空中からの地球計測とモニタリング

2017年5月24日(水) 15:30 〜 17:00 ポスター会場 (国際展示場 7ホール)

コンビーナ:楠本 成寿(富山大学大学院理工学研究部(理学))、大熊 茂雄(産業技術総合研究所地質情報研究部門)、小山 崇夫(東京大学地震研究所)、光畑 裕司(独立行政法人 産業技術総合研究所)

[STT58-P07] Three-dimensional resistivity modeling
of GREATEM survey data from Ontake Volcano,
northwest Japan

*Sabry Abd Allah1Toru Mogi2 (1.Institute of siesmology and volcanology-faculty of science, HOKKAIDO UNIVERSITY、2.Division of Sustainable resources Engineering, Faculty of Engineering, Hokkaido University )

キーワード:Airborne EM, 3D resistivity modeling, GREATEM survey, Volcanic surveys

Ontake Volcano is located in central Japan, 200 km northwest of Tokyo and erupted on September 27, 2014. To study the structure of Ontake Volcano and discuss the process of its phreatic eruption, which can help in future eruptions mitigation, airborne electromagnetic (AEM) surveys using the grounded electrical-source airborne transient electromagnetic (GREATEM) system were conducted over Ontake Volcano. Field measurements and data analysis were done by OYO Company under the Sabo project managed by the Ministry of Land, Infrastructure, Transport and Tourism.
Processed data and 1D resistivity models were provided by this project. We performed numerical forward modeling to generate a three-dimensional (3D) resistivity structure model that fits the GREATEM data where a composite of 1D resistivity models was used as the starting model. A 3D electromagnetic forward-modeling scheme based on a staggered-grid finite-difference method was modified and used to calculate the response of the 3D resistivity model along each survey line. We verified the model by examining the fit of magnetic-transient responses between the field data and 3D forward-model computed data. The preferred 3D resistivity models show that a moderately resistive structure (30–200 m) is characteristic of most of the volcano, and were able to delineate a hydrothermal zone within the volcanic edifice. This hydrothermal zone may be caused by a previous large sector collapse.