The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima's Ontake Crater continued during 16-30 December. Crater incandescence was observed nightly in webcam images. Explosions at 0221 on 16 December, and at both 0823 and 1433 on 22 December, produced ash plumes that rose 500-800 m above the crater rim and drifted E, SE, and S; the plume rose into weather clouds at 0823. An eruptive event at 1724 on 17 December generated an ash plume that rose 1 km above the crater rim and drifted E. Ashfall was occasionally observed and rumbling was heard within a 1.5-km-radius of the crater during 16-23 December, according to the Suwanosejima Branch of the Toshima Village Office (3.5 km SSW). Eruptive events at 1802 on 24 December, at 0052, 0242, 0451, and 0701 on 25 December, and at 1707 and 1806 on 30 December, produced ash plumes that rose 1-1.4 km above the cater rim and drifted S, SW, and NE. Explosions at 1903 on 28 December, at 0633 on 29 December, and at 1033 on 30 December produced ash plumes that rose 400-1,100 m above the crater rim and drifted SE; the plume on 28 December rose up into weather clouds. The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1.5 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.

Source: Japan Meteorological Agency (JMA)