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Abstract

We investigated the structural glaciology of the Nevados de Chillán Glacier, a small mountain glacier from the central-south of Chile, a glaciologic region considered as one of the most vulnerable mountain areas in the planet. We used satellite imagery to interpret several morphological descriptors. In the last decades the glacier has lost nearly 85% of its area in 1975, from 2.78km2 to 0.41 in 2022. This drastic retreat comes with important modification of the glacier morphology, first, in 1987 the glacier began to split in two tongues and, in 2018, it became disconnected from part of the accumulation area located on a crater. Currently, the glacier is fed by two small accumulation basins, with their respective ablation zones connected by an ice bridge almost completely covered by debris, also, in the middle of the main tongue there is bedrock emerging from the ice, insinuating a similar trajectory of the ridge that now divides the two glacier tongues. The clean ice surface shows a complex crevasse arrangement, with transverse crevasses on the upper reaches, intersecting both splaying and en echelon crevasses on the middle reaches, there is also a couple of icefalls generating complex crevasse zones. Analysis of preferred crevasse orientation along the glacier revealed recently exposed bedrock splitting the flow of the main tongue. These abrupt changes in glacier morphology and the shrinkage, have enhanced debris cover growth on this glacier, by exposing steep and unstable walls of volcanic sedimens.