Automated detection of basal icequakes and discrimination from surface crevassing

Icequakes at or near the bed of a glacier have the potential to allow us to investigate theinteraction of ice with the underlying till or bedrock. Understanding this interaction is important forstudying basal sliding of glaciers and ice streams, a critical process in ice dynamics models used to con-strain future sea-level rise projections. However, seismic observations on glaciers can be dominated byseismic energy from surface crevassing. We present a method of automatically detecting basal icequakesand 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 theVatnajökull Ice Cap, South-East Iceland, to demonstrate that our method outperforms the commonlyused spectrum-based method. Our method detects a higher number of basal icequakes, has a lowerrate of incorrectly identifying crevassing as basal icequakes and detects an additional, spatially inde-pendent basal icequake cluster. We also show independently that the icequakes do not originate fromnear the glacier surface. We conclude that the method described here is more effective than currentlyimplemented methods for detecting and discriminating basal icequakes from surface crevassing.

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