Instituto Geofísico del Perú (IGP) reported that lahars descended the Volcánmayo drainage on the SE flank at Ubinas at 1910 on 23 January, at 2015 on 25 January, and at 1540 on 27 January. The report noted that the lahars traveled towards the Ubinas River and could possibly impact the Districts of Ubinas, Matalaque, and population centers. The public was warned to stay away from the drainage and to avoid driving on the Querapi-Ubinas-Huarina highway. Daily gas-and-steam plumes rose 100-500 m above the summit and drifted in multiple directions during 24-30 January.

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: Instituto Geofísico del Perú (IGP)