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Report on Ubinas (Peru) — 30 April-6 May 2008


Ubinas

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 30 April-6 May 2008
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2008. Report on Ubinas (Peru) (Sennert, S, ed.). Weekly Volcanic Activity Report, 30 April-6 May 2008. Smithsonian Institution and US Geological Survey.

Weekly Report (30 April-6 May 2008)

Ubinas

Peru

16.345°S, 70.8972°W; summit elev. 5608 m

All times are local (unless otherwise noted)


Based on SIGMET reports and observations of satellite imagery, the Buenos Aires VAAC reported that ash plumes from Ubinas rose to altitudes of 5.5-9.1 km (18,000-30,000 ft) a.s.l. and drifted NE, E, and SE during 30 April-3 May. According to news articles, an ash-and-gas plume rose to an altitude of 6.2 km (20,300 ft) a.s.l. on 2 May. Ashfall was reported in local communities and dozens of residents of Querapi, about 4.5 km SE, were evacuated.

Geological Summary. The truncated appearance of Ubinas, Perú's most active volcano, is a result of a 1.4-km-wide crater at the summit. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45°. The steep-walled, 150-m-deep summit crater contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3,700 years ago extend 10 km from the volcano. Widespread Plinian pumice-fall deposits include one from about 1,000 years ago. Holocene lava flows are visible on the flanks, but activity documented since the 16th century has consisted of intermittent minor-to-moderate explosive eruptions.

Sources: NBC News, Associated Press, Buenos Aires Volcanic Ash Advisory Center (VAAC)