JMA reported that incandescence at Suwanosejima's Ontake Crater was visible nightly during 24-28 January. There were 27 explosions recorded, producing ash plumes that rose at least 3 km above the crater rim and ejected material up to 1 km away from the crater. Rumbling sounds and ashfall were reported in Toshima village (3.5 km SSW). Eruptive activity continued during 28-31 January. The Alert Level remained at 3 and the public was 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)