The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima's Ontake Crater continued during 9-16 December. Crater incandescence was observed nightly in webcam images. Blocks were ejected as far as 300 m from the center of the crater. Eruptive events at 1231 on 12 December, at 0750 on 13 December, at 1908 on 14 December, and at 0341 on 15 December produced ash plumes that rose 1-1.2 km above the cater rim and drifted S and SE; the plumes on 12 and 13 December rose into weather clouds. An explosion was recorded at 1213 on 15 December, though no emissions were reported. Another explosion at 0221 on 16 December produced an ash plume that rose 800 m above the crater rim and drifted E. 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)