Dynamic behavior of Glaciar Perito Moreno, southern Patagonia

Frontal oscillations since the beginning of the 20th century are known at Glaciar Perito Moreno. an eastward outlet glacier of Hielo Patagonico Sur (southern Patagonia ice field). In 1900, the calving front was located about 1 km from the opposite bank. From 1935 to 1988: ruptures of ice-dams occurred at intervals of 1-5 years. Although this glacier has thus oscillated, it can be regarded as having been in a rather stable condition during the last half-century. Ice thickness in the ablation area has also remained unchanged from 1990 to 1996. The near-steady behavior of Glaciar Perito Moreno may be attributed to a regulating effect of the calving rate, namely, a decrease in the ablation amount due to calving with a retreat of the glacier. Using 12 m long ablation poles, ice-flow velocities at the ablation area were measured several times in 1993 and 1994. The velocity in the early summer (November) was found to be slightly larger than the annual mean. It is concluded that basal sliding is significant throughout the year at this temperate glacier, with large fluctuations within a short period.