Combined geophysical and geotechnical approach to ground investigations and hazard zonation of a quick clay area, mid Norway

Abstract

Mapping of quick clay is important for hazard zonation, planning and protection purposes. The present study focuses on an area prone to quick clay landslides in mid Norway, which is investigated through a combination of geophysical and geotechnical methods. The following classes are suggested for a first-order interpretation of resistivity profiles in areas with few or no previous investigations: Unleached clay deposits: 1–10 Ωm; Leached clay deposits, possibly quick: 10–100 Ωm; Dry crust clay deposits and coarse sediments: >100 Ωm. In the study area, 14–80 Ωm was found as the main resistivity interval for quick clay. The resistivity values from the present study are compared to previously published values. Classification of material from resistivity values is influenced by local conditions, and there is an overlap between the classes. Resistivity profiles can give valuable information for hazard zonation and may assist in maximising subsequent intrusive investigations.