The Sofu Seamount Submarine Volcano Present in the Source Area of the October 2023 Earthquakes and Tsunamis in Japan

Abstract On 8 October 2023 (UTC), unique earthquakes occurred in the Izu‐Ogasawara Arc, Japan, in which the P‐ and S‐phases were barely visible and only the T‐phases were evident, followed by tsunamis that reached islands in the Izu‐Ogasawara Arc and a wide area of the Pacific coast of southwest Jap...

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Main Authors: Toshiya Fujiwara, Kentaro Imai, Masayuki Obayashi, Kenta Yoshida, Noriko Tada, Koichiro Obana, Gou Fujie, Shigeaki Ono, Shuichi Kodaira
Format: Article
Language:English
Published: Wiley 2024-10-01
Series:Geophysical Research Letters
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Online Access:https://doi.org/10.1029/2024GL109766
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author Toshiya Fujiwara
Kentaro Imai
Masayuki Obayashi
Kenta Yoshida
Noriko Tada
Koichiro Obana
Gou Fujie
Shigeaki Ono
Shuichi Kodaira
author_facet Toshiya Fujiwara
Kentaro Imai
Masayuki Obayashi
Kenta Yoshida
Noriko Tada
Koichiro Obana
Gou Fujie
Shigeaki Ono
Shuichi Kodaira
author_sort Toshiya Fujiwara
collection DOAJ
description Abstract On 8 October 2023 (UTC), unique earthquakes occurred in the Izu‐Ogasawara Arc, Japan, in which the P‐ and S‐phases were barely visible and only the T‐phases were evident, followed by tsunamis that reached islands in the Izu‐Ogasawara Arc and a wide area of the Pacific coast of southwest Japan. Our estimated T‐phase source area coincides with the Sofu Seamount, which was previously unrecognized as an active submarine volcano. A bathymetric survey of the seamount conducted 1 month after the event revealed characteristics of the seamount with a caldera and a central cone. Compared to the bathymetry in 1987, the topography in the caldera had changed significantly such as a crater forming in the central cone. This seamount is likely to be an active volcano. The topographic changes on the caldera‐sized scale that occurred at the caldera can be explained as a source of the October tsunami.
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publishDate 2024-10-01
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record_format Article
series Geophysical Research Letters
spelling doaj-art-21ea26c2d2da4acda8db524741f32f562025-08-20T02:04:20ZengWileyGeophysical Research Letters0094-82761944-80072024-10-015119n/an/a10.1029/2024GL109766The Sofu Seamount Submarine Volcano Present in the Source Area of the October 2023 Earthquakes and Tsunamis in JapanToshiya Fujiwara0Kentaro Imai1Masayuki Obayashi2Kenta Yoshida3Noriko Tada4Koichiro Obana5Gou Fujie6Shigeaki Ono7Shuichi Kodaira8Research Institute for Marine Geodynamics Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanResearch Institute for Marine Geodynamics Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanResearch Institute for Marine Geodynamics Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanResearch Institute for Marine Geodynamics Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanResearch Institute for Marine Geodynamics Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanResearch Institute for Marine Geodynamics Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanResearch Institute for Marine Geodynamics Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanResearch Institute for Marine Geodynamics Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanJapan Agency for Marine‐Earth Science and Technology (JAMSTEC) Yokosuka JapanAbstract On 8 October 2023 (UTC), unique earthquakes occurred in the Izu‐Ogasawara Arc, Japan, in which the P‐ and S‐phases were barely visible and only the T‐phases were evident, followed by tsunamis that reached islands in the Izu‐Ogasawara Arc and a wide area of the Pacific coast of southwest Japan. Our estimated T‐phase source area coincides with the Sofu Seamount, which was previously unrecognized as an active submarine volcano. A bathymetric survey of the seamount conducted 1 month after the event revealed characteristics of the seamount with a caldera and a central cone. Compared to the bathymetry in 1987, the topography in the caldera had changed significantly such as a crater forming in the central cone. This seamount is likely to be an active volcano. The topographic changes on the caldera‐sized scale that occurred at the caldera can be explained as a source of the October tsunami.https://doi.org/10.1029/2024GL109766sofu seamountt‐phasetsunamicalderasubmarine volcanorepeat bathymetric survey
spellingShingle Toshiya Fujiwara
Kentaro Imai
Masayuki Obayashi
Kenta Yoshida
Noriko Tada
Koichiro Obana
Gou Fujie
Shigeaki Ono
Shuichi Kodaira
The Sofu Seamount Submarine Volcano Present in the Source Area of the October 2023 Earthquakes and Tsunamis in Japan
Geophysical Research Letters
sofu seamount
t‐phase
tsunami
caldera
submarine volcano
repeat bathymetric survey
title The Sofu Seamount Submarine Volcano Present in the Source Area of the October 2023 Earthquakes and Tsunamis in Japan
title_full The Sofu Seamount Submarine Volcano Present in the Source Area of the October 2023 Earthquakes and Tsunamis in Japan
title_fullStr The Sofu Seamount Submarine Volcano Present in the Source Area of the October 2023 Earthquakes and Tsunamis in Japan
title_full_unstemmed The Sofu Seamount Submarine Volcano Present in the Source Area of the October 2023 Earthquakes and Tsunamis in Japan
title_short The Sofu Seamount Submarine Volcano Present in the Source Area of the October 2023 Earthquakes and Tsunamis in Japan
title_sort sofu seamount submarine volcano present in the source area of the october 2023 earthquakes and tsunamis in japan
topic sofu seamount
t‐phase
tsunami
caldera
submarine volcano
repeat bathymetric survey
url https://doi.org/10.1029/2024GL109766
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