Sub-Decadal Volcanic Tsunamis Due To Submarine Trapdoor Faulting at Sumisu Caldera in the Izu-Bonin Arc - Archive ouverte HAL Access content directly
Journal Articles Journal of Geophysical Research : Solid Earth Year : 2022

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

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1
Osamu Sandanbata
  • Function : Author
Shingo Watada
  • Function : Author
Kenji Satake
  • Function : Author
Hiroo Kanamori
  • Function : Author
Zhongwen Zhan
  • Function : Author

Abstract

The main cause of tsunamis is large subduction zone earthquakes with seismic magnitudes Mw > 7, but submarine volcanic processes can also generate tsunamis. At the submarine Sumisu caldera in the Izu-Bonin arc, moderate-sized earthquakes with Mw < 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.
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insu-03824789 , version 1 (21-10-2022)

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Attribution - CC BY 4.0

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Osamu Sandanbata, Shingo Watada, Kenji Satake, Hiroo Kanamori, Luis Rivera, et al.. Sub-Decadal Volcanic Tsunamis Due To Submarine Trapdoor Faulting at Sumisu Caldera in the Izu-Bonin Arc. Journal of Geophysical Research : Solid Earth, 2022, 127, ⟨10.1029/2022JB024213⟩. ⟨insu-03824789⟩
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