Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima's Ontake Crater continued during 30 September-7 October. Crater incandescence was observed nightly in webcam images. Three eruptive events on 30 September produced ash-and-gas plumes that rose 1-1.3 km above the crater rim and drifted W. At 0031 on 1 October continuous ash-and-gas plumes rose 0.6-1.1 km above the crater rim and drifted W, N, and NE; ash was no longer detected by 1710. An eruptive event on 4 October generated an ash-and-gas plume that rose 1.5 km above the crater rim. Continuous ash-and-gas emissions that began at 1256 on 4 October likely ceased around 0620 on 5 October, although weather conditions obscured views; ash-and-gas plumes rose as high as 2 km above the crater rim and drifted NE, N, and NW. On 7 October ash-and-gas plumes rose 1.1-1.5 km 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)