Report on Ubinas (Peru) — 13 May-19 May 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 May-19 May 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Ubinas (Peru). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 13 May-19 May 2020. Smithsonian Institution and US Geological Survey.
16.355°S, 70.903°W; summit elev. 5672 m
All times are local (unless otherwise noted)
During 11-18 May the number of seismic events at Ubinas totaled 54 with volcano-tectonic (VT) signals being the most numerous. Sporadic emissions of gas and steam were recorded by the webcam rising to heights less than 300 m above the summit. The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 10-km radius.
Geologic Background. A small, 1.4-km-wide caldera cuts the top of Ubinas, Perú'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. 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 3,700 years ago extend 10 km from the volcano. Widespread Plinian pumice-fall deposits include one of Holocene age about 1,000 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.