Rapid sequestration of rock avalanche deposits within glaciers

• Published in: Nature communications 2015-08, Vol.6 (1), p.7964-7964, Article 7964
• Main Authors: Dunning, Stuart A., Rosser, Nicholas J., McColl, Samuel T., Reznichenko, Natalya V.
• Format: Article
• Language: English
• Subjects: 704/2151/213; 704/2151/2809; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms8964

Topographic development in mountainous landscapes is a complex interplay between tectonics, climate and denudation. Glaciers erode valleys to generate headwall relief, and hillslope processes control the height and retreat of the peaks. The magnitude–frequency of these landslides and their long-term ability to lower mountains above glaciers is poorly understood; however, small, frequent rockfalls are currently thought to dominate. The preservation of rarer, larger, landslide deposits is exceptionally short-lived, as they are rapidly reworked. The 2013 Mount Haast rock avalanche that failed from the slopes of Aoraki/Mount Cook, New Zealand, onto the glacier accumulation zone below was invisible to conventional remote sensing after just 3 months. Here we use sub-surface data to reveal the now-buried landslide deposit, and suggest that large landslides are the primary hillslope erosion mechanism here. These data show how past large landslides can be identified in accumulation zones, providing an untapped archive of erosive events in mountainous landscapes. Small, frequent rockfalls are thought to dominate the erosion of mountains above rockfalls, and little is known about rare large landslides as material is rapidly reworked. Here, the authors present sub-surface data from a large rock avalanche showing how such landslides can be recognized from their deposits.