Microtremor measurements and the horizontal-to-vertical spectral ratio (HVSR)
technique, generally used for site effect studies as well as to determine the
thickness of soft sedimentary layers, can effectively be applied to map the
thickness of glaciers. In this work the radio-echo sounding, geoelectric and
active seismic methods, widely employed to image the earth interior, are applied
to verify the reliability of the HVSR technique in Alpine and Antarctic glacial
environments. The technique has been used to analyze passive seismic data from
glaciers of the Adamello and Ortles-Cevedale massifs (Italy), the Bernese
Oberland Alps (Switzerland) and from the Whillans Ice Stream (West Antarctica).
Comparing with the results obtained from the different geophysical imaging
methods, we show that the resonance frequency in the HVSR spectra correlates
well with the ice thickness at the site, in a wide range from a few tens of
meters to more than 800 m. The reliability of the method mainly depends
on the coupling of sensors at the glacier surface and on the basal impedance
contrast. This passive seismic technique offers a logistically efficient and
cost effective method to map glacier and ice-sheet thicknesses. Moreover, under
certain conditions, it allows reliable estimations of the basal seismic
properties.