Geophysical surveys for the characterization of periglacial mountain environments

The degradation of mountain permafrost is well documented at many Alpine areas. During the last decades, geophysical techniques have been intensively used to monitor these sites, since thawing permafrost is a proxy of climate change and global warming but also a possible source of slope instabilities and triggering of mass movements. Consequently, the development of new reliable geophysical methods to study Alpine mountain permafrost areas have both an economic and scientific interest. This PhD project has been focused on the application and optimization of different geophysical techniques, data acquisition and processing, for the characterization of several periglacial mountain environments in the Alps and Apennines. The works that have been realized during the PhD period can be divided into four different categories: i) evaluation and optimization of the contact resistances between electrodes and debris-blocky surfaces during electrical resistivity tomography (ERT) measurements, with the application of conductive textile sachets as substitute of traditional stainless steel rod electrodes; ii) application of different electromagnetic instruments in the frequency domain (FDEM) to rapidly verify the presence in the subsurface of the frozen layer and its thickness; iii) optimization of two joint inversion methods, structurally-coupled and petrophysical-coupled joint inversions, applied to seismic refraction (RST) and ERT datasets to improve the structural interpretation of the inverted models, thanks to sharper boundaries between the different layers, and the evaluation of ice, water, and air fractions in the subsurface; iv) evaluation of the hydraulic behaviour of the active layer and the frozen layer in a mountain permafrost area with an infiltration experiment combined with ERT time-lapse measurements.