Northern Central Andes, Peru	image info
	Ubinas
Synonyms: Uvinas, Uvillas
Location: 16º22'S; 70º54'W
Type: Composite
Summit Elevation: 5675m
Edifice Height: 1200m
Status: Fumarolic

A broad, quasi-symmetrical cone, Ubinas has a truncated appearance from the ground due to a large summit crater. The cone steepens towards the summit with slopes of almost 45° near the summit.

The summit complex consists of a large (1.2 km diameter), steep walled (100 -150 m high) outer caldera whose floor is ash covered. An ash cone occupies the central portion of the caldera and is itself truncated to the south by the most recent vent (SC); a triangular funnel shaped depression 500 m in diameter and ~200 m deep. According to Hantke & Parodi (1966) the floor of the vent is flat and is about 100 m in diameter. It may be a frozen lava lake.

Several young lava flows (L) are present on the western flanks overlying terminal moraines (M) related to the 10,000 yr BP glacial regression. Bright material on the NE slopes is probably an airfall ash from a recent eruption; possibly the 1600 A.D. eruption of Huaynaputina (q.v.) 15 km to the south.

Ubinas has been intermittently active throughout historic time. Eruptions have been reported from 1677, 1784, and there were several in the 1800s. Last reported activity was in 1956, which consisted of vulcanian ash eruptions during which crops and livestock in Ubinas village (6 km to SE; U) were damaged (Hantke & Parodi, 1966).

Weak fumarolic activity from the crater was reported during a visit to the summit in 1985 (McLelland et al., 1989). Persistent minor steam and fumarolic activity continues to the present day.

The main pathways for any pyroclastic flows or mudflows are on the southeastern side of the volcano. Many small settlements (including Ubinas; U) have developed along the deep quebrada which starts on the southeast of the volcano. This quebrada joins the Rio de la Para and then the larger Rio Tambo which continues some 80 -100 km westwards to the Pacific coast. In the event of a pyroclastic eruption, such as occurred at the nearby Huaynaputina, in 1600 A.D., mud flow, or avalanche from Ubinas there would be considerable hazard to the many communities along these quebradas.

Bullard, F.M. 1962. Volcanoes of southern Peru. Bull. Volcanol. XXIV: 443-453.

de Silva S.L., & Francis, P.W., 1990. Active and potentially active volcanoes of southern Peru - observations using Landsat Thematic Mapper and Space Shuttle imagery. Bull. Volcanol. 52, 286-301.

Hantke, G., & Parodi, A., 1966. Catalogue of the active volcanoes of the world; Part XIX, Colombia, Ecuador & Peru, I.A.V.C.E.I. Naples, Italy, 73pp.

McLelland, L., Simkin, T., Summers, M., Nielsen, E., and Stein, T.C., (eds.) 1989. Global Volcanism 1975-1985. National Museum of Natural History. Prentice-Hall Inc., New Jersey, pp655.