The 2016 Lamplugh rock avalanche, Alaska: Deposit structures and emplacement dynamics

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Supraglacial landslides result from the catastrophic failure of periglacial rock slopes and deposit large volumes of rock and ice onto the glacier surface. The most remarkable features of these landslides are their prominent long flowbands and a high mobility that exceeds that of their counterparts in other environments. Based on field surveys, high-resolution digital elevation models, and continuous seismic data, we show that the emplacement dynamics of the 2016 rock avalanche on Lamplugh Glacier were characterized by two distinct stages. During the first stage, the debris traveled about 5 km from the base of the slope. Clear long-period seismic signals during this stage record strong interactions of the rock avalanche debris with the ground, suggesting dynamic processes such as grain collisions and fragmentation. The second stage was essentially aseismic at long periods and dominated by low-friction sliding at slow deceleration rates. A higher density of flowbands and increased entrainment of snow from the runout path characterize the morphology of this second-stage distal deposition. Around the margins, lobes are offset by up to 400 m along major strike-slip faults, whereas within individual lobes, offsets between flowbands are much less pronounced (0 to < 10 m). The two-stage emplacement model may explain the higher apparent mobility of supraglacial landslides.

Study Area

Publication type Article
Publication Subtype Journal Article
Title The 2016 Lamplugh rock avalanche, Alaska: Deposit structures and emplacement dynamics
Series title Landslides
DOI 10.1007/s10346-019-01225-4
Volume 16
Issue 12
Year Published 2019
Language English
Publisher Springer
Contributing office(s) Geologic Hazards Science Center
Description 19 p.
First page 2301
Last page 2319
Country United States
State Alaska
Other Geospatial Glacier Bay National Park
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