EGU21-3591, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-3591
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Anatomy of a volcanic island inferred from a multiphysics approach

Marceau Gresse1, Makoto Uyeshima1, Takao Koyama1, Hideaki Hase2, Koki Aizawa3, Yusuke Yamaya4, Yuichi Morita1, Derek Weller1, Tawat Rung-Arunwan5, Takayuki Kaneko1, Yoichi Sasai6, Jacques Zlotnicki7, Tsuneo Ishido8, Hideki Ueda9, and Maki Hata1
Marceau Gresse et al.
  • 1The University of Tokyo, Earthquake Research Institute (ERI), Volcano Research Center, Tokyo, Japan
  • 2Geothermal Energy Research and Development Co., Ltd., Tokyo, Japan
  • 3Institute of Seismology and Volcanology, Faculty of Science, Kyushu University, Fukuoka, Japan
  • 4National Institute of Advanced Industrial Science and Technology (AIST), Renewable Energy Research Center, Fukushima, Japan
  • 5Curl-E Geophysics Co., Ltd., Thailand
  • 6Earthquake Prediction Research Center, Tokai University, Shizuoka, Japan
  • 7CNRS, EMSEV, OPGC-UMR6524, Aubière, France
  • 8Geological Survey of Japan (GSJ), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
  • 9National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan

Phreatic and phreatomagmatic eruptions are difficult to predict with accuracy on volcanoes due to complex interactions at depth between heat, water, and magmatic fluids. To better understand such multifaceted interactions, we present here a multidisciplinary geophysical approach performed on Miyakejima, a 10-km wide stratovolcano in the Izu Bonin arc. Its plumbing system was highlighted by combining four geophysical methods: magnetotellurics, seismicity (hypocenters), self-potential, and thermal image (remote sensing). We thus propose the first large-scale interpretation of the volcanic structure in terms of rock properties, temperature, fluid content, and fluid flow. Our findings indicate that hot volatiles released from a deep magmatic reservoir (> 350°C, 2.5–4.5 km depth) rise through a narrow permeable path, interact with the conductive hydrothermal system beneath the 2000 A.D. caldera (<250°C, 0–2 km depth). This mixture of fluid is finally released in the fumarolic area in the southern part of the caldera at 181°C. This combined approach allow us to: 1) delineate the water table of the volcano (300–700 m depth), 2) determine the general fluid flow circulation beneath the island, 3) characterize seismic signatures of long-period and volcano-tectonic events, and 4) elucidate the origin of the high water content of fumaroles developed since the last eruption in A.D. 2000.

How to cite: Gresse, M., Uyeshima, M., Koyama, T., Hase, H., Aizawa, K., Yamaya, Y., Morita, Y., Weller, D., Rung-Arunwan, T., Kaneko, T., Sasai, Y., Zlotnicki, J., Ishido, T., Ueda, H., and Hata, M.: Anatomy of a volcanic island inferred from a multiphysics approach, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3591, https://doi.org/10.5194/egusphere-egu21-3591, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.