JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 8-15 May and crater incandescence was reported nightly. Explosions recorded at 0701, 1200, and 2330 on 8 May produced ash plumes that rose as high as 1 km above the crater rim and mainly drifted SE. Explosions were also recorded at 1358 and 1648, though characteristics of associated emissions were unknown. Eruptive events at 2001 on 8 May, 1753 on 9 May, 0405, 0647, and 1236 on 11 May, and 1919 on 13 May generated ash plumes that rose as high as 1.3 km and generally drifted S, SW, and N. The Alert Level remained at 3 (on a 5-level scale) and residents were warned to stay 2 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)