Abstract
ABSTRACTOver a year of seismic observations, ~5000 short duration icequakes were detected by a permanent broadband station installed at the Princess Elisabeth base, located ~180 km inland in eastern Dronning Maud Land, East-Antarctica. Icequake detection via seismic waveform pattern recognition indicates the presence of two dominating clusters of events, totalizing ~1500 icequakes. The corresponding icequake locations point towards two distinct zones of outcropping blue ice areas (BIAs) located respectively at 4 and 1 km from the seismic station, both on the leeward side of a nunatak protruding through the ice sheet. The temporal occurrence of these icequakes suggests a close genetic link with thermal contraction of ice caused by significant surface cooling controlled, in summer by variations in diurnal solar radiation and in winter by strong cooling during cold katabatic regimes. Further analysis demonstrates the dependence of these icequakes on the absolute surface temperature and on its temporal change. Besides providing information on the ice fracture mechanics and rheology, investigations of thermal icequakes may be regarded as a ground-based proxy for the monitoring of the thermal state of BIAs, and characterization of ice-sheet ablation zones.
Highlights
In the recent years, the growing interest in understanding rapid changes in the cryosphere dynamics has promoted passive seismology as a major tool in the field of glaciology (Podolskiy and Walter, 2016; Aster and Winberry, 2017)
The present paper aims at complementing those studies, providing local observations of thermal stress-induced seismicity over a whole year (February 2012 to January 2013) by using data recorded by permanent seismic and weather stations installed near the Princess Elisabeth Antarctica base (71.94°S, 23.34°E, hereafter referred to as ‘PEA’), located
Over the year-long dataset, 1500 seismic events were detected and categorized into two clusters based on their seismic waveforms and durations. Their source location on two blue ice areas (BIAs) and their dependence on large diurnal temperature variability mainly due to daily solar radiation in summer or cold katabatic regime in winter suggest they are associated with thermal contraction of blue ice
Summary
The growing interest in understanding rapid changes in the cryosphere dynamics has promoted passive seismology as a major tool in the field of glaciology (Podolskiy and Walter, 2016; Aster and Winberry, 2017). These cold periods are observed with a daily recurrence in summer due to large diurnal variability in the incoming solar radiation and occasionally in winter characterized by katabatic winds from the Antarctic plateau and clear sky conditions associated with strong surface cooling They may not be located in confined areas but may rather be spread all around the station, generating varying waveforms and may not be detected via our waveform pattern recognition procedure
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