Summary
The Ground Penetrating Radar (GPR) survey in the Alta area of Finnmark County, Norway, supported by NGU and NVE, aimed to update outdated Quaternary geological maps and better understand subsurface geology. Conducted in August 2020, the survey covered 14 locations, utilizing PulseEKKO Pro and Malå RTA systems to analyse depositional environments and sedimentary structures. The GPR methods revealed variations in reflectivity, attenuation, and layering. Northern areas, such as Altahøyden and Tverrelva valley, showed moderate to shallow penetration due to fine-grained, water-rich sediments, but still provided insights into subsurface transitions. Southern areas, composed of coarser, permeable sediments, allowed deeper penetration, revealing clearer stratigraphy and geological features, such as dipping layers and basin-like structures. A separate GPR profile at Kråkneset, site of a major June 2020 quick clay landslide, identified horizontal layers with a coarse-grained top overlying fine, attenuative sediments, aligning with observed geohazard conditions. Noise from nearby infrastructure posed challenges, particularly in areas like Energiveien and Altahøyden, but selective analysis still uncovered valuable geological details. Overall, the survey enhanced understanding of the region’s complex geology, surveying fluvial, deltaic, and marine processes, and providing updated data for geohazard assessment and landscape interpretation.
