Recent evolution and degradation of the bent Jatunraju glacier (Cordillera Blanca, Peru)

- Mean annual surface velocities in the lower part of the Jatunraju significantly decreased.
- Altitude border between ice-cored rock glacier and debris-covered glacier increased.
- Cycle of formation and extinction of supraglacial lakes accelerates degradation.
- Overall stability of entire Jatunraju body is not influenced.

This article brings new insight into the recent evolution and degradation of the bent Jatunraju glacier in the northern part of the Cordillera Blanca, Peru. Analysis of topographical maps, aerial photos and satellite images covering a period of 66 years and a field survey performed in June 2013 and May 2014 helped to describe the geomorphological setting and ongoing processes. Recent evolution and degradation processes are also deduced from surface movements. Historical geodetic measurements (1967-1968; 1977-1984) and current LANDSAT images (2001-2013) were used to estimate surface velocities and changes in surface velocities over time. Our investigation showed that the most significant changes happened at an altitude of between 4300 and 4450 m asl. A significant decrease in surface velocities and increase in debris thickness indicate that this part of Jatunraju turned from a debris-covered glacier into an ice-cored rock glacier during the analyzed period. Particular parts of the article describe the cycle of formation and extinction of supraglacial lakes and the melting of buried (debris-covered) ice. A scenario of future evolution is outlined and discussed as well. We assume that ice degradation within the debris-covered glacier will continue and that the altitude of its presence will increase hand-in-hand with the changing environment.