Bibliographic Details
| Title: |
Accelerating Seafloor Uplift of Submarine Caldera Near Sofugan Volcano, Japan, Resolved by Distant Tsunami Recordings. |
| Authors: |
Kubota, Tatsuya, Sandanbata, Osamu, Saito, Tatsuhiko, Matsuzawa, Takanori |
| Source: |
Geophysical Research Letters; 6/28/2024, Vol. 51 Issue 12, p1-11, 11p |
| Subject Terms: |
TSUNAMIS, SUBMARINE volcanoes, CALDERAS, VOLCANOES, EARTHQUAKES, PRESSURE gages |
| Geographic Terms: |
BONIN Islands (Japan), JAPAN |
| Abstract: |
On 8 October 2023 UTC, significant tsunamis were observed around Japan without any major tsunamigenic earthquake, associated with a series of 14 successive minor earthquakes (mb = 4.5–5.4) near Sofugan in the Izu‐Bonin Islands. To examine the cause of this tsunami, we estimated the horizontal locations of the tsunami source and temporal history of the seafloor displacement, using the tsunami data recorded by the ocean‐bottom pressure gauges >∼600 km away. Our results showed the main tsunami source was an uplift located at a caldera‐like bathymetric feature near Sofugan, suggesting the involvement of caldera activity in the tsunami generation. The total seafloor uplift was estimated as ∼4 m, and the uplift amount of each event gradually increased over time, reflecting an accelerating occurrence of volcanic unrest of the submarine caldera within only a few hours. Plain Language Summary: On 8 October 2023, a tsunami was widely observed along the Japanese coast without any major tsunamigenic earthquake, while a series of 14 small earthquakes occurred near Sofugan, located in the Izu‐Bonin Islands. Two possible candidates for this tsunami have been proposed, involving submarine volcanic processes or submarine landslides, but the exact cause remains unclarified. Using the tsunami data observed by the seafloor pressure gauges located more than 600 km from the tsunami source region, we analyzed sea height movements to obtain insights into the origin of this enigmatic tsunami. Our analysis showed that the tsunami source consisted of the seafloor uplift that repetitively occurred at a submarine volcanic caldera. Our results also showed an accelerating tsunami excitation, such that the amount of the seafloor uplift movement increased over time and the time intervals of the earthquakes gradually shortened. These results are consistent with the acceleration process of volcanic activity, suggesting the tsunami originated from the multiple sudden uplifts of the submarine caldera. Key Points: We revealed the source kinematics of enigmatic tsunamis excited near Torishima on 8 October 2023 with remote (>∼600 km) tsunami dataIts tsunami source was identified as repetitive seafloor uplift at the same location with gradually increasing amounts for later eventsThis unique feature of the accelerating caldera uplift within a few hours was brought about by the volcanic unrest of a submarine caldera [ABSTRACT FROM AUTHOR] |
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| Database: |
Complementary Index |
