Using structure from motion photogrammetry to examine glide snow avalanches

Structure from Motion (SfM), a photogrammetric technique, has been used extensively
and successfully in many fields including geosciences over the past few years to create 3D models and
high resolution digital elevation models (DEMs) from aerial or oblique photographs. SfM has recently
been used in a limited capacity in snow avalanche research and shows promise as a tool for broader applications.
In this study, we used SfM to examine glide avalanches along the Going-to-the-Sun Road
(GTSR) corridor in Glacier National Park (GNP), Montana. Glide avalanches pose substantial hazard to
railroads, highways, and other infrastructure in many avalanche prone regions around the world, and yet
basic measurements of crown depth and ground/snow interface can be hard to observe. Along the GTSR,
glide avalanches can impact worker and public safety, but accessing glide avalanche crowns or glide
cracks is often prohibited by inaccessible terrain or residual avalanche hazard. We used SfM techniques
to derive high resolution DEMs for four glide avalanches that occurred in the spring of 2016. This allowed
us to estimate selected full depth glide avalanche dimensions without visiting the site. However, our analysis
was limited to qualitative assessments of the glide avalanche dimensions as the high resolution coordinates
necessary to analyze the vertical dimension of avalanche crowns were not available. Despite this,
our results suggest SfM can be a robust tool for examining glide avalanche crowns and of sufficient resolution
to accurately characterize glide avalanche dimensions. Under a warming and more variable future
climate, glide avalanches could become a more prevalent problem, and using SfM as a tool to help characterize
glide avalanches over a larger spatial area will help us to better document and further understand
these phenomena.