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Sub-Decadal Volcanic Tsunamis Due To Submarine Trapdoor Faulting at Sumisu Caldera in the Izu-Bonin Arc

Sandanbata, Osamu and Watada, Shingo and Satake, Kenji and Kanamori, Hiroo and Rivera, Luis and Zhan, Zhongwen (2022) Sub-Decadal Volcanic Tsunamis Due To Submarine Trapdoor Faulting at Sumisu Caldera in the Izu-Bonin Arc. Journal of Geophysical Research. Solid Earth, 127 (9). Art. No. e2022JB024213. ISSN 2169-9313. doi:10.1029/2022jb024213.

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The main cause of tsunamis is large subduction zone earthquakes with seismic magnitudes M_w > 7, but submarine volcanic processes can also generate tsunamis. At the submarine Sumisu caldera in the Izu–Bonin arc, moderate-sized earthquakes with M_w < 6 occur almost once a decade and cause meter-scale tsunamis. The source mechanism of the volcanic earthquakes is poorly understood. Here we use tsunami and seismic data from the recent 2015 event to show that abrupt uplift of the submarine caldera, with a large brittle rupture of the ring fault system due to overpressure in its magma reservoir, caused the earthquake and tsunami. This submarine trapdoor faulting mechanism can efficiently generate tsunamis due to large vertical seafloor displacements, but it inefficiently radiates long-period seismic waves. Similar seismic radiation patterns and tsunami waveforms due to repeated earthquakes indicate that continuous magma supply into the caldera induces quasi-regular trapdoor faulting. This mechanism of tsunami generation by submarine trapdoor faulting underscores the need to monitor submarine calderas for robust assessment of tsunami hazards.

Item Type:Article
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URLURL TypeDescription ItemDiscussion paper
Sandanbata, Osamu0000-0002-2361-8482
Watada, Shingo0000-0001-9924-968X
Satake, Kenji0000-0002-3368-3085
Kanamori, Hiroo0000-0001-8219-9428
Rivera, Luis0000-0002-0726-5445
Zhan, Zhongwen0000-0002-5586-2607
Additional Information:We thank Paul Segall and an anonymous reviewer for their constructive comments to improve our manuscript. We thank Editor, Rachel Abercrombie, and Associate Editor, Lingling Ye, for their valuable suggestions. We thank Aditya Gusman for providing the digitized tide gauge data. We thank Dapeng Zaho for providing the velocity model used in our computation of seismic waves. We thank Yoshio Fukao, Hiroko Sugioka, Aki Ito, and Hajime Shiobara for helping obtain some of the tsunami data. This research was funded by JSPS KAKENHI (Grants JP17J02919, JP20J01689, and JP19K04034) and JST J-RAPID (Grant JPMJJR1805). The travel of Osamu Sandanbata to the California Institute of Technology was supported by the Overseas Internship Program of the Earthquake Research Institute, The University of Tokyo.
Group:Seismological Laboratory
Funding AgencyGrant Number
Japan Society for the Promotion of ScienceJP17J02919
Japan Society for the Promotion of ScienceJP20J01689
Japan Society for the Promotion of ScienceJP19K04034
Japan Society for the Promotion of ScienceJPMJJR1805
University of TokyoUNSPECIFIED
Issue or Number:9
Record Number:CaltechAUTHORS:20220926-576554400.8
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117141
Deposited By: Melissa Ray
Deposited On:04 Oct 2022 14:56
Last Modified:04 Oct 2022 14:56

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