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SEISMIC NETWORK ENABLES ASSESSMENT OF FLOOD DYNAMICS BENEATH AN ICELANDIC GLACIER

ROBERTS, MATTHEW J  Physics Department, Icelandic Meteorological Office.
Björnsson, Helgi  Science Institute, University of Iceland.
Pįlsson, Finnur  Science Institute, University of Iceland.
Gušmundsson, Gunnar B  Physics Department, Icelandic Meteorological Office.

Sensor-based observations of glacier floods (jökulhlaups) have given impetus to an emerging paradigm shift in glaciology. Formerly, the predominant view was that floodwater travelled within a single conduit eroded into the underside of a glacier; but the latest hypotheses unite empirical and theoretical evidence to show that floodwater permeates large zones of the glacier bed, before draining from isolated vents. Despite resurgent interest in jökulhlaup hydraulics, the capricious timing and intensity of jökulhlaups continues to put human activity at risk. We report here about a regional network of digital, three-component seismometers that communicate distinct seismicity immediately before and during jökulhlaups that propagate beneath the glacier Skeišarįrjökull, Iceland. We exploit this unique circumstance to enable (i) an empirical assessment of jökulhlaup dynamics beneath Skeišarįrjökull; and (ii) an evaluation of the utility of glacier seismicity as a basis for short-term forecasts about jökulhlaup probability.


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