According to the Washington VAAC an ash puff from Ubinas was identified in a satellite image at 0040 on 11 December rising 5.5 km (18,000 ft) a.s.l. and drifting NW. Webcam images at 0620 and 1220 showed continuous steam emissions possibly containing diffuse ash rising as high as 7 km (23,000 ft) a.s.l. Steam emissions containing small amounts of ash were visible at 1810. Emissions were no longer visible in satellite and webcam images at 0010 on 12 December.

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.

Source: Washington Volcanic Ash Advisory Center (VAAC)