JMA reported that the eruption at Suwanosejima’s Ontake Crater continued during 5-12 February. Crater incandescence was observed in thermal webcam images. A total of two eruptions were reported; large volcanic blocks were ejected as far as 500 m away from the vent. The eruptions recorded at 1147 on 6 February and 1314 on 12 February produced ash plumes that rose 1 km above the crater rim before drifting SE and S, respectively. Seismicity consisted of a few volcanic earthquakes detected in the W area of the island, and episodes of tremor that occurred at the same time as the eruptive events. The Alert Level remained at 2 (on a 5-level scale), and the public was warned to stay at least 1 km away from Ontake crater in all directions.

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)