Quick-clay Landslide-prone Grounds in Norway and Sweden:A Complex Problem Requiring a Combined Geophysical and Geotechnical Approach

Quick-clay sliding occurs in formerly glaciated coastal areas in, e.g., Norway, Sweden and Canada. The soil was originally deposited in shallow marine environments which emerged following isostatic rebound and fall of the relative sea level since the last glacial maximum. Long-term leaching of salt, due to groundwater flow and percolating surface water, affects clay-particles bonding and makes the soil highly susceptible to failure when disturbed. We review the properties of quick-clays in order to define a suitable, integrated and multi-disciplinary approach to improve identification and mapping of quick-clay areas. Though electrical resistivity tomography is actually the geophysical method of choice, it is paramount to combine a range of geophysical and geotechnical approaches for a better assessment of a given quick-clay site. The discussed integrated approach is here presented for 2 Norwegian and 1 Swedish quick-clay sites. The collected data and preliminary site characterization will illustrate the high diversity of quick-clay grounds as well as the complexity related to an integrated approach.