Report on Ubinas (Peru) — 6 August-12 August 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 6 August-12 August 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Ubinas (Peru). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 6 August-12 August 2014. Smithsonian Institution and US Geological Survey.
16.355°S, 70.903°W; summit elev. 5672 m
All times are local (unless otherwise noted)
During 6-9 August INGEMMET reported that the eruption of Ubinas was continuing. On 6-7 August gas-and-minor ash emissions rose 300-1200 m above the crater and drifted NE and S. On 6 August ash was reported in the village of Para (NE). On 8-9 August, white emissions of primarily water vapor rose 100-300 m above the crater and drifted S and SE. On 6 August Buenos Aires VAAC reported intermittent light volcanic ash and emission puffs to 6.7 km (22,000 ft)a.s.l. and continuous emissions of gases and light ash on 7 August.
Geologic Background. A small, 1.4-km-wide caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Perú. 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 degrees. The steep-walled, 150-m-deep summit caldera 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 3700 years ago extend 10 km from the volcano. Widespread plinian pumice-fall deposits include one of Holocene age about 1000 years ago. Holocene lava flows are visible on the flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.