October 8, 2023 Eruption of Sofugan

Our bathymetric comparisons suggest that Sofu Seamount began the 2023 eruptive activity after at least 36 years of quiescence since 1987 […] Repeat bathymetric surveys reveal that a deep explosive eruption occurred at the western central cone between December 2022 and January 2024. Repeat bathymetric surveys were utilized to quantify the area and volume of depth changes of the volcano associated with the eruption. The eruption formed a 1.6 km-wide and 400 m-deep crater at the summit of the central cone with a previous summit depth of 737 m. The maximum negative depth change was -451 m. The crater formation removed a total of 430 × 106 m3 materials from the central cone. The eruption formed a new dome which is 1 kmwide and 100 m-high near the central cone, but it was partially destroyed by the crater formation. The largest landslide occurred north of the crater, which produced 3.8 km-long, 1 km-wide scour that exhibits a negative depth change of -148 m. The landslides removed a total of 141 × 106 m3 of materials. The erupted and collapsed materials were emplaced around the crater with a positive depth change up to +75 m. The timing of the eruption can be constrained to October 9, 2023 when T-phase swarm and tsunamis were observed to have originated near Sofu Seamount after the 7 day-long earthquake swarm during October 2–8. (reference #14219)