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Report on Suwanosejima (Japan) — 20 September-26 September 2006


Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 20 September-26 September 2006
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2006. Report on Suwanosejima (Japan) (Sennert, S, ed.). Weekly Volcanic Activity Report, 20 September-26 September 2006. Smithsonian Institution and US Geological Survey.

Weekly Report (20 September-26 September 2006)



29.638°N, 129.714°E; summit elev. 796 m

All times are local (unless otherwise noted)

On 20 September the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite caught Suwanose-jima in the process of emitting volcanic ash and steam. The volcano's emissions blew N, gradually fanning out over the ocean, with a grayish tinge that distinguished it from nearby white clouds. Aviation ash advisories for this eruption issued by the Tokyo VAAC based on satellite imagery, pilot reports, and JMA, noted that the plume rose to 2.1 km (7,000 ft) a.s.l. and extended about 80 km N.

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.

Sources: NASA Earth Observatory, Tokyo Volcanic Ash Advisory Center (VAAC)