Report on Ubinas (Peru) — 9 April-15 April 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 April-15 April 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, 9 April-15 April 2014. Smithsonian Institution and US Geological Survey.
16.355°S, 70.903°W; summit elev. 5672 m
All times are local (unless otherwise noted)
IGP's Observatorio Volcanologico de Arequipa (IGP-OVA) and Observatorio Vulcanológico del INGEMMET (OVI) reported that during 9-14 April seismicity at Ubinas remained high. Gas-and-ash plumes rose 0.3-2.2 km above the crater and drifted mostly E, SE, and S. Ashfall was reported in Ubinas (6.5 km SSE), Huatagua (14 km SE), Anascapa (11 km SE), Tonohaya (7 km SSE), San Miguel (10 km SE), Sacuaya, Querapi (4 km S), San Juan de Tarucani, Escacha, Ichuña, Yungas, and Chojata. On 13 April a significant explosion occurred that possibly removed the body of recently erupted lava on the crater floor; incandescent tephra was ejected from the crater. On 14 April an explosion ejected incandescent tephra from the crater that was deposited on the W flank.
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.