Techniques and methods in landslide mapping

NGU uses a range of remote sensing, dating and geophysical techniques, as well as advanced digital methods and classification systems, in order to map the various types of landslides in Norway.
NGU scientist Gro Sandøy, working with Terrestrial Laser Scanning, during the investigations of the mountain "Mannen" in 2014.
NGU scientist Gro Sandøy, working with Terrestrial Laser Scanning, during the investigations of the mountain "Mannen" in 2014.

Instruments used in remote sensing consist of all those that collect data about an area without making physical contact. The main tools used in landslide mapping are aerial-based Digital Elevation Models (DEM), Digital Photogrammetry, Interferometric Synthetic Aperture Radar (InSAR) and Terrestrial Laser Scanning (TLS). These tools contribute to mapping at a highly detailed level with the help of 3D models and other analysis methods.

2D Electrical Resistivity Imaging is a useful supplementary tool used to identify the location of quick clay, which is key to preventing and reducing loss due to quick clay slides. This method may also be used when carrying out a detailed analysis of unstable slopes. For dating past rock avalanche events, cosmogenic nuclide dating is often used. Finally, an extensometer is a portable instrument used to measure the openings (cracks) found on unstable rock slopes.

When mapping landslides, a variety of software programmes are used, including programmes for run-out modelling of various types of landslides and for the structural and kinematic analysis of unstable rock slopes.

NGU conducts mapping of unstable rock slopes throughout Norway and has developed its own approach for systematic mapping and a hazard and risk classification system with input from landslides experts world-wide.