Report on Aira (Japan) — 31 May-6 June 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 May-6 June 2006
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2006. Report on Aira (Japan). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 31 May-6 June 2006. Smithsonian Institution and US Geological Survey.
31.593°N, 130.657°E; summit elev. 1117 m
All times are local (unless otherwise noted)
On 4 and 5 June, intermittent eruptions at Sakura-jima, from an upper E-flank vent, near or within the 1946 vent, produced ash clouds that reached unknown heights. No ash was visible on satellite imagery. This was the first reported Sakura-jima eruption from a vent outside the summit crater in 58 years. The 1946 vent was the source of major lava flows that reached the E and S coasts of the former island.
Geologic Background. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.
Sources: Reuters, Yukio Hayakawa, Gunma University