Report on Suwanosejima (Japan) — 24 January-30 January 2024
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 24 January-30 January 2024
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2024. Report on Suwanosejima (Japan) (Sennert, S, ed.). Weekly Volcanic Activity Report, 24 January-30 January 2024. Smithsonian Institution and US Geological Survey.
Suwanosejima
Japan
29.638°N, 129.714°E; summit elev. 796 m
All times are local (unless otherwise noted)
JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 22-29 January. A total of 15 explosions were recorded during the week, with 1-4 occurring each day. Ash plumes rose as high as 1 km above the crater rim and drifted SE and E, and large blocks were ejected as far as 400 m from the vent. Crater incandescence was observed in webcam images nightly and rumbling was occasionally heard in Toshima village (3.5 km SSW). The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1 km away from the crater.
Geological Summary. The 8-km-long island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two active summit craters. The summit is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. One of Japan's most frequently active volcanoes, it was in a state of intermittent Strombolian activity from Otake, the NE summit crater, between 1949 and 1996, after which periods of inactivity lengthened. The largest recorded eruption took place in 1813-14, when thick scoria deposits covered residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed, forming a large debris avalanche and creating an open collapse scarp extending to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.