Surface‐Wave Relocation and Characterization of the October 2023 Tsunamigenic Seismic Unrest Near Sofugan Volcano, Izu Islands, Japan
Abstract A moderate‐magnitude earthquake swarm occurred in the remote Izu Islands region of Japan between October 1 and 8, 2023. The swarm included 151 shallow earthquakes cataloged by the U.S. Geological Survey, which notably included a roughly 2.5‐hr episode of 15 successive magnitude (M) < 5.5...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2025-02-01
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| Series: | Geophysical Research Letters |
| Online Access: | https://doi.org/10.1029/2024GL113504 |
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| Summary: | Abstract A moderate‐magnitude earthquake swarm occurred in the remote Izu Islands region of Japan between October 1 and 8, 2023. The swarm included 151 shallow earthquakes cataloged by the U.S. Geological Survey, which notably included a roughly 2.5‐hr episode of 15 successive magnitude (M) < 5.5 earthquakes. Origin times were coincident with regionally recorded tsunami waves, but tsunamigenesis for moderate‐magnitude earthquakes is uncommon, indicating that volcanic activity generated the ocean displacements. Leveraging a surface‐wave relative relocation approach, we estimate precise epicentroid locations for the remote swarm. Final epicentroids and caldera analogs indicate a three‐stage model to explain swarm activity: (a) caldera pressurization due to magma intrusion, (b) depressurization via dike propagation away from the caldera, and (c) eruption corresponding with caldera reactivation either by collapse or additional intrusion. |
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| ISSN: | 0094-8276 1944-8007 |