资源环境科技发展态势分析平台

Sliding of glacial ice over its base is typically described by a frictionless or slowly deforming bed. This view is challenged by recent seismic observations of stick‐slip motion at the ice‐bed interface. We revisit a high‐frequency (20‐35 Hz) harmonic tremor recorded on Gornergletscher, Switzerland. In contrast to previous interpretation in terms of glaciohydraulic tremor, we present evidence for superimposed stick‐slip episodes as tremor sources: we locate the tremor source with matched field processing polarity optimization, which allows for azimuthal polarity patterns associated with non‐isotropic moment tensors and yields a tremor source clustering near the glacier bed. Our analysis confirms an S‐wave radiation pattern in agreement with a double‐couple source derived from ice sliding over bedrock and explains our tremor observations in terms of glacier stick‐slip motion. Adding to observations of stick‐slip tremor beneath polar ice streams, this first report on stick‐slip tremor beneath Alpine ice favors widespread seismogenic glacier sliding.