An automated approach to the location of icequakes using seismic waveform amplitudes

Authors Organisations
Type Article
Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalAnnals of Glaciology
Volume54
Issue number64
DOI
Publication statusPublished - Sep 2013
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Abstract

We adapt from volcano-seismology an automated method of locating icequakes with poorly-defined onsets and indistinguishable seismic phases, which can be tuned to either body or surface waves. The method involves: (1) the calculation of the root-mean-squared (RMS) amplitudes of the filtered envelope signals; (2) a coarse-grid search to locate the hypocentres of the seismic events using their amplitudes; and (3) refinement of hypocentre locations using an iteratively damped least-squares approach. First, we calibrate the adapted method by application to real data, recorded using a network of six passive seismometers, in response to surface explosions in known locations on the western margin of the Greenland Ice Sheet. Secondly we present a seismic modelling experiment simulating rapid supraglacial lake drainage-driven hydrofracture through 1 km thick ice. The test reveals horizontal and vertical location uncertainties of several tens of metres and 200-300m repectively. Since seismic emissions from glaciers and ice sheets often have complex waveforms akin to those considered here, our adapted method will likely have widespread applicability to glaciological problems.

Keywords

  • seismics, glacier , seismology, supraglacial lake