Three-Dimensional Resistivity Structure of Iwo-Yama Volcano, Kirishima Volcanic Complex, Japan

Relationship to Shallow Seismicity, Surface Uplift, and a Small Phreatic Eruption

K. Tsukamoto, Koki Aizawa, K. Chiba, W. Kanda, M. Uyeshima, T. Koyama, M. Utsugi, K. Seki, T. Kishita

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Iwo-yama volcano, part of the Kirishima Volcanic Complex, has recently shown signs of unrest. We conducted a hypocenter relocation of shallow earthquakes and broadband magnetotelluric measurements around Iwo-yama. Three-dimensional inversion of magnetotelluric data revealed an electrically conductive layer that is interpreted as a hydrothermally altered clay-dominated unit. Shallow earthquakes occur beneath this layer, suggesting that it controls the location of seismicity. The base of the layer corresponds to the depth of a pressure source identified by a leveling survey. These observations suggest that the supply of high-temperature fluids has increased over time beneath Iwo-yama, causing an increase in pore pressure beneath the clay-rich layer and resulting in tectonic earthquakes and ground inflation. Increased upwelling of fluids through a fracture in the clay-rich layer may have caused a vigorous liquid-gas phase transition near the surface, which in turn might have led to the small phreatic eruption on 19 April 2018.

Original languageEnglish
Pages (from-to)12,821-12,828
JournalGeophysical Research Letters
Volume45
Issue number23
DOIs
Publication statusPublished - Dec 16 2018

Fingerprint

volcanoes
volcanic eruptions
seismicity
electrical resistivity
volcanology
Japan
volcano
volcanic eruption
uplift
clays
earthquakes
clay
earthquake
high temperature fluids
relocation
fluid
leveling
upwelling water
phase transition
inflation

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

Three-Dimensional Resistivity Structure of Iwo-Yama Volcano, Kirishima Volcanic Complex, Japan : Relationship to Shallow Seismicity, Surface Uplift, and a Small Phreatic Eruption. / Tsukamoto, K.; Aizawa, Koki; Chiba, K.; Kanda, W.; Uyeshima, M.; Koyama, T.; Utsugi, M.; Seki, K.; Kishita, T.

In: Geophysical Research Letters, Vol. 45, No. 23, 16.12.2018, p. 12,821-12,828.

Research output: Contribution to journalArticle

Tsukamoto, K. ; Aizawa, Koki ; Chiba, K. ; Kanda, W. ; Uyeshima, M. ; Koyama, T. ; Utsugi, M. ; Seki, K. ; Kishita, T. / Three-Dimensional Resistivity Structure of Iwo-Yama Volcano, Kirishima Volcanic Complex, Japan : Relationship to Shallow Seismicity, Surface Uplift, and a Small Phreatic Eruption. In: Geophysical Research Letters. 2018 ; Vol. 45, No. 23. pp. 12,821-12,828.
@article{3f1084c5906242ac85c90da5f7f9eb54,
title = "Three-Dimensional Resistivity Structure of Iwo-Yama Volcano, Kirishima Volcanic Complex, Japan: Relationship to Shallow Seismicity, Surface Uplift, and a Small Phreatic Eruption",
abstract = "Iwo-yama volcano, part of the Kirishima Volcanic Complex, has recently shown signs of unrest. We conducted a hypocenter relocation of shallow earthquakes and broadband magnetotelluric measurements around Iwo-yama. Three-dimensional inversion of magnetotelluric data revealed an electrically conductive layer that is interpreted as a hydrothermally altered clay-dominated unit. Shallow earthquakes occur beneath this layer, suggesting that it controls the location of seismicity. The base of the layer corresponds to the depth of a pressure source identified by a leveling survey. These observations suggest that the supply of high-temperature fluids has increased over time beneath Iwo-yama, causing an increase in pore pressure beneath the clay-rich layer and resulting in tectonic earthquakes and ground inflation. Increased upwelling of fluids through a fracture in the clay-rich layer may have caused a vigorous liquid-gas phase transition near the surface, which in turn might have led to the small phreatic eruption on 19 April 2018.",
author = "K. Tsukamoto and Koki Aizawa and K. Chiba and W. Kanda and M. Uyeshima and T. Koyama and M. Utsugi and K. Seki and T. Kishita",
year = "2018",
month = "12",
day = "16",
doi = "10.1029/2018GL080202",
language = "English",
volume = "45",
pages = "12,821--12,828",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "23",

}

TY - JOUR

T1 - Three-Dimensional Resistivity Structure of Iwo-Yama Volcano, Kirishima Volcanic Complex, Japan

T2 - Relationship to Shallow Seismicity, Surface Uplift, and a Small Phreatic Eruption

AU - Tsukamoto, K.

AU - Aizawa, Koki

AU - Chiba, K.

AU - Kanda, W.

AU - Uyeshima, M.

AU - Koyama, T.

AU - Utsugi, M.

AU - Seki, K.

AU - Kishita, T.

PY - 2018/12/16

Y1 - 2018/12/16

N2 - Iwo-yama volcano, part of the Kirishima Volcanic Complex, has recently shown signs of unrest. We conducted a hypocenter relocation of shallow earthquakes and broadband magnetotelluric measurements around Iwo-yama. Three-dimensional inversion of magnetotelluric data revealed an electrically conductive layer that is interpreted as a hydrothermally altered clay-dominated unit. Shallow earthquakes occur beneath this layer, suggesting that it controls the location of seismicity. The base of the layer corresponds to the depth of a pressure source identified by a leveling survey. These observations suggest that the supply of high-temperature fluids has increased over time beneath Iwo-yama, causing an increase in pore pressure beneath the clay-rich layer and resulting in tectonic earthquakes and ground inflation. Increased upwelling of fluids through a fracture in the clay-rich layer may have caused a vigorous liquid-gas phase transition near the surface, which in turn might have led to the small phreatic eruption on 19 April 2018.

AB - Iwo-yama volcano, part of the Kirishima Volcanic Complex, has recently shown signs of unrest. We conducted a hypocenter relocation of shallow earthquakes and broadband magnetotelluric measurements around Iwo-yama. Three-dimensional inversion of magnetotelluric data revealed an electrically conductive layer that is interpreted as a hydrothermally altered clay-dominated unit. Shallow earthquakes occur beneath this layer, suggesting that it controls the location of seismicity. The base of the layer corresponds to the depth of a pressure source identified by a leveling survey. These observations suggest that the supply of high-temperature fluids has increased over time beneath Iwo-yama, causing an increase in pore pressure beneath the clay-rich layer and resulting in tectonic earthquakes and ground inflation. Increased upwelling of fluids through a fracture in the clay-rich layer may have caused a vigorous liquid-gas phase transition near the surface, which in turn might have led to the small phreatic eruption on 19 April 2018.

UR - http://www.scopus.com/inward/record.url?scp=85058473812&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85058473812&partnerID=8YFLogxK

U2 - 10.1029/2018GL080202

DO - 10.1029/2018GL080202

M3 - Article

VL - 45

SP - 12,821-12,828

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 23

ER -