Controlling factors for slope instability in a seismically active region: The NW-Svalbard continental margin

Abstract

Slope failures are widespread along the Norwegian-Svalbard passive continental margin. Here, we describe the morphology and sedimentology of a slide area and discuss the potential trigger mechanisms that have led to multiple slope failure events along the NW-Svalbard margin, in close proximity to the tectonically active Spitsbergen Fracture Zone. Bathymetric data reveal a headwall and slide scar of a new slide area of ~230km2 and net volume of ~4.5km3, which we refer to as the Spitsbergen Fracture Zone Slide (SFZS). Analysis of local earthquake records reveals numerous high magnitude events up to 6.6M with extreme peak ground acceleration of 0.16g within the slide scars suggesting that such earthquake events are a likely trigger. Results obtained from 14C dating of N. pachyderma sin. from sediments cores acquired at the slide indicate a maximum 14C-age of >43,500yr BP that constrains the long-term sedimentation rate to ~6cm/ka. Correlation with the regional magnetic susceptibility stratigraphic record suggests an age of ~130,000yr BP for the SFZS event. We conclude that despite high seismic activity and local potential for gas-hydrate dissociation, this sector of the Arctic margin has not experienced a major slide for over 100,000years due predominantly to low regional sedimentation rates.