Dynamics of a small surge-type glacier, St. Elias Mountains, Yukon Territory, Canada: characterization of basal motion using 1-D geophysical inversion

The dynamics of a small surge-type glacier are investigated as part of a study to characterize glacier response to climate in southwest Yukon Territory, Canada. DEMs of the glacier surface and bed are constructed from surface elevation and ice thickness data. Measured surface velocities are higher than expected for a surge-type glacier in its quiescent phase over the upper 3500m of the 5km-long glacier, but much lower than typical surge velocities. Flowline basal velocities are reconstructed from the measured surface velocities using a 1-D geophysical inverse model. Control tests are used to validate the inversion scheme, and sensitivity tests are performed to evaluate the influence of uncertain parameters. Inversion of the measured surface velocities reveals an unusually high contribution of basal motion to the overall motion. Based on these results and several other lines of evidence, we suggest that the glacier may be undergoing a slow surge.