Supercritical fluid flow through permeable window and phase transitions at volcanic brittle–ductile transition zone
Journal
Communications Earth & Environment
Journal Volume
6
Journal Issue
1
ISSN
2662-4435
Date Issued
2025-09-24
Author(s)
Tsuji, Takeshi
Andajani, Rezkia Dewi
Katou, Masafumi
Hara, Akio
Aoki, Naoshi
Abe, Susumu
Guan, Zhuo-Kang
Sun, Wei-Fang
Pan, Sheng-Yan
Liu, Yao-Hung
Kitamura, Keigo
Nishijima, Jun
Inagaki, Haruhiro
Abstract
Hydrothermal fluid migration and supercritical phase transitions around the brittle–ductile transition are key to understanding volcanic activity and geothermal energy, but it remains challenging due to limited subsurface imaging. Here we conducted active-source seismic surveys at Kuju volcano, Japan, applying extended common-reflection-surface analysis to image magma-related and hydrothermal structures. We further estimated earthquake hypocenters, focal mechanisms, and seismic velocity. A continuous horizontal reflector could indicate a low-permeability seal confining supercritical fluids, while a low-amplitude reflection zone reveals fractures disrupting the seal. This permeable window, located at the magma margin, coincides with earthquake clusters of various focal mechanisms, suggesting upward fluid migration. A plume-shaped zone with low P-wave and S-wave velocity ratio (Vp/Vs) above the permeable window indicates thermally-altered formations and gas release from phase transitions. These results provide 3D visualization of the interplay among trapped supercritical fluid, its migration through permeable window, and related seismicity near the brittle-ductile transition. (Figure presented.)
Subjects
Japan
earthquake hypocenter
focal mechanism
hydrothermal fluid
P-wave
permeability
phase transition
plume
S-wave
seismic survey
seismic velocity
supercritical flow
thermal alteration
SDGs
Publisher
Springer Science and Business Media LLC
Type
journal article