Report on Ubinas (Peru) — 19 March-25 March 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 19 March-25 March 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, 19 March-25 March 2014. Smithsonian Institution and US Geological Survey.
16.355°S, 70.903°W; summit elev. 5672 m
All times are local (unless otherwise noted)
In a 23 March news article IGP volcanologists noted that the seismic network at Ubinas indicated a large output of lava during 10-11 March; sulfur dioxide emissions also increased during this period. Lava in the crater was incandescent. Based on analysis of satellite images and the INGEMMET web cam, the Buenos Aires VAAC reported that an emission of gas and steam on 23 March possibly contained diffuse ash. The plume drifted NE before dissipating about 55 km away. The next day another steam-and-gas emission possibly containing some ash drifted NE.
On 25 March Observatorio Vulcanológico del INGEMMET (OVI) reported that in the previous days bluish white gas plumes rose 1.3 km above the crater rim and sulfur dioxide emissions averaged 2,200 tons per day. The report also noted that lava had continued to erupt in recent weeks.
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.