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Report on Ubinas (Peru) — 14 October-20 October 2015

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 October-20 October 2015
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2015. Report on Ubinas (Peru). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 14 October-20 October 2015. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (14 October-20 October 2015)


Ubinas

Peru

16.355°S, 70.903°W; summit elev. 5672 m

All times are local (unless otherwise noted)


Instituto Geofísico del Perú (IGP) Observatorio Volcanológico del Sur (OVS) reported that during 13-19 October seismicity at Ubinas fluctuated; moderate levels of seismicity were detected near the beginning of the period but then declined during the second half of the week. Thermal anomalies were detected during 13-14 October. Five explosions generated ash plumes that rose 2 km above the crater on 15 October.

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.

Source: Instituto Geofísico del Perú (IGP)