[S-VC47] [JJ] Active volcanism

[SVC47-18] Geoelectromagnetic investigations of Yake-dake volcano - wideband magnetotelluric measurements and magnetic survey -

*Ryokei Yoshimura¹, Takeshi Hashimoto², Masahiro Miyazaki¹, Jun Nakagawa¹, Masato Kamo¹, Kotaro Sugano³, Masahito Takata⁴, Tsutomu Miura¹, Mikihiro Nakamoto¹, Kana Araue¹, Ken'ichi Yamazaki¹, Shiro Ohmi¹, Masato Iguchi¹ (1.Disaster Prevention Research Institute, Kyoto University, 2.Institute of Seismology and Volcanology, Graduate School of Science, Hokkaido University, 3.Graduate School of Science, Hokkaido University, 4.School of Science, Hokkaido University)

Keywords:Yake-dake volcano, magnetotellurics, ground magnetic survey

In order to delineate subsurface structures as basic information for monitoring Yake-dake volcano, we carried out wideband magnetotelluric (MT) measurements. For clarifying electrical properties, we totally obtained electromagnetic data at 11 sites along a north-south profile and estimated MT responses by using the remote reference technique. Obtained preliminary result of a two-dimensional inversion reveals a cap-like conductor just beneath the latest phreatic eruption. Additionally, we performed ground magnetic survey along a north-south profile crossing the summit of Yake-dake volcano. To simulate obtained magnetic anomaly, a zone of low magnetization is required at the same location as the cap-like conductor.