Ground thermal conditions at Chachani Volcano, Southern Peru

Abstract

Shallow ground temperatures were measured and periglacial and permafrost environments identified at the Chachani volcanic complex in the west-central Andes in southern Peru (16° 11′ S; 71° 31′ W, elevation 6057 m a.s.l.). Three stations were installed at 4850, 4976 and 5331 m a.s.l. on the southern slope and the data were processed to produce ground temperature distribution models at depth and altitude. Snow cover lasts only a few days each year. Air and ground surface temperatures oscillate around 0°C almost daily, but the temperature is stabilized only a few centimetres below the ground surface. The lower limit of thermal conditions for isolated patches of permafrost occurs at 5050 m on the south-facing slopes. Thermal conditions associated with discontinuous permafrost occur from 5250 to 5420 m a.s.l., with continuous permafrost found above this level. The permafrost distribution models show that the rock glaciers observed on the southern slopes of the complex are within the active permafrost zone.