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Shallow resistivity structure around the 2018 craters of Mt. Motoshirane of Kusatsu-Shirane Volcano, Japan, revealed by audio-frequency magnetotellurics

Authors :
Asami Honda
Wataru Kanda
Takao Koyama
Shinichi Takakura
Yasuo Matsunaga
Tatsuji Nishizawa
Satoshi Ikezawa
Source :
Earth, Planets and Space, Vol 75, Iss 1, Pp 1-15 (2023)
Publication Year :
2023
Publisher :
SpringerOpen, 2023.

Abstract

Abstract In 2018, a phreatic eruption occurred at Mt. Motoshirane, a pyroclastic cone group of the Kusatsu-Shirane Volcano in central Japan. The eruption was abrupt, and no signs of volcanic activity have been observed in recent years, in contrast to the other major pyroclastic cone group, Mt. Shirane, which hosts the active crater lake and has endured repeated phreatic eruptions. To understand the mechanism of the eruption at Mt. Motoshirane, information on the shallow hydrothermal system, which is thought to be the source region of phreatic eruptions, is required; however, few studies have been conducted on this particular cone group. In this study, we conducted an audio-frequency magnetotelluric survey in 2020 to reveal the shallow resistivity structure around the 2018 craters. A three-dimensional resistivity structure model showed generally two layers, with high resistivities at shallow depths overlain by low resistivities underneath. The boundary between the layers corresponded to the top boundary of the Neogene basement rocks. These low resistivities were not found beneath the 2018 craters; therefore, part of the Neogene basement rocks could have been lost by the eruption beneath the 2018 craters. This is consistent with the geochemical study on the mineral assemblage of the erupted deposits, which suggested that the explosions reached the depth of the basement. Graphical Abstract

Details

Language :
English
ISSN :
18805981
Volume :
75
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Earth, Planets and Space
Publication Type :
Academic Journal
Accession number :
edsdoj.23ea6381944fc197ca039557a31a19
Document Type :
article
Full Text :
https://doi.org/10.1186/s40623-023-01799-3