Atypical landslide induces speedup, advance, and long-term slowdown of a tidewater glacier
Willis, Michael J.
- 1University of Minnesota System
- 2Macalester College
- 3
- 4University of Colorado System
Journal
Geology
ISSN
0091-7613
1943-2682
Open Access
hybrid
Volume
50
Start page
806
End page
811
Atmospheric and oceanic warming over the past century have driven rapid glacier thinning and retreat, destabilizing hillslopes and increasing the frequency of landslides. The impact of these landslides on glacier dynamics and resultant secondary landslide hazards are not fully understood. We investigated how a 262 +/- 77 x 10(6) m(3) landslide affected the flow of Amalia Glacier, Chilean Patagonia. Despite being one of the largest recorded landslides in a glaciated region, it emplaced little debris onto the glacier surface. Instead, it left a series of landslide-perpendicular ridges, landslide-parallel fractures, and an apron of ice debris-with blocks as much as 25 m across. Our observations suggest that a deep-seated failure of the mountainside impacted the glacier flank, propagating brittle deformation through the ice and emplacing the bulk of the rock mass below the glacier. The landslide triggered a brief downglacier acceleration of Amalia Glacier followed by a slowdown of as much as 60% of the pre-landslide speed and increased suspended-sediment concentrations in the fjord. These results highlight that landslides may induce widespread and long-lasting disruptions to glacier dynamics.