Report on Novarupta (United States) — 2 November-8 November 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
2 November-8 November 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on Novarupta (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 2 November-8 November 2005. Smithsonian Institution and US Geological Survey.
58.27°N, 155.157°W; summit elev. 841 m
All times are local (unless otherwise noted)
Strong winds in the Katmai area picked up loose ash deposited during the 1912 eruption and carried it E over Kodiak Island. AVO recorded a large area of resuspended ash on satellite imagery. The National Weather Service estimated that the top of the plume was at 1.5 km (5,000 ft) a.s.l. Katmai remained at Concern Color Code Green.
Geological Summary. Novarupta, the least topographically prominent volcano in the Katmai area, was formed during a major eruption in 1912. This eruption was the world's largest during the 20th century and produced a voluminous rhyolitic airfall tephra and the renowned Valley of Ten Thousand Smokes (VTTS) ash flow. At the end of the eruption a small, 65-m-high, 400-m-wide lava dome grew to an elevation of 841 m within the source vent of the VTTS ashflow, a 2-km-wide area of subsidence NW of Trident volcano. The NE side of the Falling Mountain lava dome of the Trident volcanic cluster, as well as Broken Mountain and Baked Mountain, was removed by collapse of the Novarupta depression, which is marked by radial and scalloped arcuate fractures. Much larger collapse took place at Katmai volcano, 10 km to the east, where a 3 x 4 km wide caldera formed in response to magma reservoir drainage toward Novarupta.