The Comité Científico de Monitoreo Permanente del volcán Ubinas, made up of scientists from IGP's Observatorio Vulcanológico del Sur (OVS) and INGEMMET's Observatorio Vulcanológico (OVI), reported that at 1829 on 17 November an explosion at Ubinas generated an ash plume that rose 500 m above the crater rim and drifted W.

Geological Summary. The truncated appearance of Ubinas, Perú's most active volcano, is a result of a 1.4-km-wide crater at the summit. 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°. The steep-walled, 150-m-deep summit crater 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 from about 1,000 years ago. Holocene lava flows are visible on the flanks, but activity documented since the 16th century has consisted of intermittent minor-to-moderate explosive eruptions.

Sources: Observatorio Vulcanológico del INGEMMET (OVI), Instituto Geofísico del Perú (IGP)