Forkastningsfjellet Rock Slide, Spitsbergen: State of Activity in a Changing Climate

The coastal ridge of Forkastningsfjellet comprises a ~100 million m³ rock rotational slide, which occurred in the hangingwall of a listric, northwest-dipping slide surface, probably in postglacial times. Active mass wasting and seacliff erosion, mainly controlled by the inherent discontinuities of the fractured and tilted rock masses, currently take place along the steep slopes of the coastal tilt blocks. A catastrophic reactivation of such slide blocks as very rapid rock slide could have severe consequences for the surrounding coastal regions and for Longyearbyen, the capital of Spitsbergen, which is situated nearby. This paper introduces the present knowledge about the rock slide and describes the current multidisciplinary investigation program that is conducted to better understand the nature and state of activity of the rock slide. The investigation is necessary to improve the hazard assessment of Forkastningsfjellet rock slide, which also serves as a showcase for the impact of climate change on landslide activity in the Longyearbyen region.