GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 New evidence from integrated GPR attributes analysis of the Von Postbreen polythermal glacier, Svalbard P. Gutgesell, E. Forte Department of Mathematics and Geosciences, University of Trieste, Italy Introduction and objectives We reanalyzed the GPR data discussed in Delf et al. (2022). Such a paper highlights the thermal structure of the Von Postbreen polythermal glacier exploiting GPR data and focusing on the diffraction hyperbola analysis as a tool for estimating the EM waves velocity and in turn the water amount inside the glacier. Our analysis aims to extent the previously obtained results further considering the signature of the data and discriminating different zones inside the glacier. In particular, we found specific and previously not apparent patterns considering not only amplitude analyses but some more complex GPR attributes. Such a method shows its effectiveness to detected warm and cold ice zones inside a glacier (Forte et al., 2020; Santin et al., 2019), glaciological transformations and firnification processes (Zhao et al., 2006) and also to image buried objects and debris- rich zones within glaciers (Forte et al., 2021; King et al., 2008). In fact, one of the main open issues in glaciology is how GPR, often integrated by other measurements (e.g. temperature borehole or geomorphological evidence) can highlight and discriminate the warm/cold ice facies from other zones possibly related to different glaciological processes or features that could occur inside glaciers. all these zones are in fact visualized in amplitude GPR sections as high scattered EM patterns, which are usually associated to warm ice or water pockets/channels in the available literature (Bælum and Benn, 2011; Irvine-Fynn et al., 2006; Pettersson et al., 2003, Seveste et al., 2015). We re-analyzed the same GPR section published in Delf et al., 2022 that images the central portion of the Von Postbreen polythermal glacier in the Tempelfjorden region of Svalbard Islands. All the details about the data acquisition and processing are available in the Delf et al., 2022 who made freely available the processed GPR data set. We focused on data interpretation, exploiting different GPR attributes and specifically frequency- and phase-related attributes as a tool for detecting peculiar patterns and glaciological facies not apparent on usual reflection amplitude data.