Monitoring displacement on the Mannen rockslide in Western Norway

Abstract

In Norway, four large rock slides are considered high-risk objects and equipped with real time early warning system. The mountain Mannen is the most recently instrumented of those. Construction and instrumentation was started in 2009 and was almost completed in 2010. To ensure redundancy, several types of instruments are used, such as lasers, realtime DGPS, extensometers, ground based InSAR system, borehole instrumentation and a meteorological station. The surface displacement is about 3 cm/year, with the largest velocity in the upper part, where the annual probability of failure estimated to 1/100. Strong subsurface deformation is measured in a 120 m borehole, suggesting a complex movement in a graben structure at the back-crack. © Springer-Verlag Berlin Heidelberg 2013.