Periglacial environment, permafrost and natural hazards in an extinct tropical volcano: Nevado Chachani (Southern Peru)

Abstract

The Nevado Chachani (16 ° 11 'S 71 ° 31' W, 6057 m asl) is located in the Cordillera Occidental of the Central Andes (Southern Peru), 22 km from the city of Arequipa. No current or recent eruptive activity has been recorded or detected. Rock glaciers can be found on south-facing slopes, some of them showing geomorphologic evidence of activity. The presence of these landforms has led to the approach the objective of this work which consists of delineating the extent in which thermal characteristics allow the existence of periglacial processes and performs a first approach to the location of permafrost in the Nevado Chachani. The importance of the permafrost distribution, and its relationship to Global Change, lies in the presence of important water resource and the economic consequences that could lead to human communities the changes in these systems. Three sampling stations were installed on the Southeast slope of the volcano complex (4850, 4976 and 5331 m) with an air probe and ground probes at several depths. The analysis of the distribution of air temperatures indicates that the lower limit of periglacial area is located at 4651 m and above 5617 m the freezing processes are dominant. Furthermore, the implementation of permafrost distribution model indicates the possible existence of permafrost above 5050 m on the southern slopes.