Fine Structure of Microseismic Glacial Stick‐Slip

Frictional instabilities exist in many geological settings, including glaciers and tectonic plate boundaries. However, investigations of suggested analogies between stick-slip “icequakes” earthquake faulting have been hampered by the noisy, melt-prone inaccessible nature glacial environments. Here, we reveal details events beneath an Alpine glacier using seismic sensors within a few meters seismically active bed region. We present evidence that widely detected events, which are measurable at ice surface, fact dynamic ruptures over smaller asperities, whose individual failures usually too small to be recorded surface. Characteristic recurrence times such multi-asperity their sizes suggest analogy Parkfield earthquakes on San Andreas Fault, questioning traditional sliding theories. Although several trillion smaller, sources presented here may therefore ideal for studying due much higher event rates.