Report on Ubinas (Peru) — 19 June-25 June 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
19 June-25 June 2019
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2019. Report on Ubinas (Peru). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 19 June-25 June 2019. Smithsonian Institution and US Geological Survey.
16.355°S, 70.903°W; summit elev. 5672 m
All times are local (unless otherwise noted)
Instituto Geofísico del Perú (IGP) reported that seismic activity at Ubinas increased suddenly on 18 June with signals indicating rock fracturing. During 21-24 June signals indicating fluid movement emerged and, beginning at 0700 on 24 June, webcams recorded ash, gas, and steam plumes rising from the crater. The plumes were visible in satellite images rising to 6.1 km (20,000 ft) a.s.l. and drifting N, NE, and E. IGP recommended that the authorities raise the Alert Level to Yellow (on a 4 level scale).
Geological Summary. 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.