In Nordic countries, so called quick-clays play a important role regarding safe building settlements, especially for essential infrastructures. Deposited in a marine or brackish environment originally, quick-clay formations composed of silt and clay are exposed to freshwater due to the isostatic uplift above sea
level after deglaciation. This caused leaching to low salinity, which may destabilize the formation, up to a sudden liquefaction collapse. The
detection of safe building ground e.g. bedrock and the knowledge of the internal soil structure above is therefore essential in areas prone to quick-clay deposits.