Abstract
ABSTRACTIcequakes at or near the bed of a glacier have the potential to allow us to investigate the interaction of ice with the underlying till or bedrock. Understanding this interaction is important for studying basal sliding of glaciers and ice streams, a critical process in ice dynamics models used to constrain future sea-level rise projections. However, seismic observations on glaciers can be dominated by seismic energy from surface crevassing. We present a method of automatically detecting basal icequakes and discriminating them from surface crevassing, comparing this method to a commonly used spectrum-based method of detecting icequakes. We use data from Skeidararjökull, an outlet glacier of the Vatnajökull Ice Cap, South-East Iceland, to demonstrate that our method outperforms the commonly used spectrum-based method. Our method detects a higher number of basal icequakes, has a lower rate of incorrectly identifying crevassing as basal icequakes and detects an additional, spatially independent basal icequake cluster. We also show independently that the icequakes do not originate from near the glacier surface. We conclude that the method described here is more effective than currently implemented methods for detecting and discriminating basal icequakes from surface crevassing.
Highlights
Icequakes at or near the ice/bed interface of a glacier have recently been the subject of a number of studies (see Podolskiy and Walter (2016); Aster and Winberry (2017) and references therein)
These icequakes, referred to as basal icequakes, are important because they provide the potential to elucidate the interaction of ice with the underlying till or bedrock. This interaction is important for constraining basal sliding in ice dynamics models, a significant but relatively poorly understood process that is critical in improving sea-level rise projections (Morlighem and others, 2010; Ritz and others, 2015)
To test the effectiveness of QuakeMigrate compared to common icequake detection methods reported in the literature, we present results on the performance of the QuakeMigrate detection method for the seismic network deployed at Skeidararjökull, independently confirm that the detected deep icequakes are approximately basal in origin and compare the effectiveness of the QuakeMigrate method to the spectrum-based method
Summary
Icequakes at or near the ice/bed interface of a glacier have recently been the subject of a number of studies (see Podolskiy and Walter (2016); Aster and Winberry (2017) and references therein) These icequakes, referred to as basal icequakes, are important because they provide the potential to elucidate the interaction of ice with the underlying till or bedrock. This interaction is important for constraining basal sliding in ice dynamics models, a significant but relatively poorly understood process that is critical in improving sea-level rise projections (Morlighem and others, 2010; Ritz and others, 2015). This software has been made publicly available, and the software combined with the details provided here will provide a useful and accessible tool for future cryoseismological investigations
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