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

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 ~ 230 km2 and net volume of ~ 4.5 km3, which we refer to as the Spitsbergen Fracture Zone Slide (SFZS). Analysis of local earthquake records reveals numerous high magnitude events up to 6.6 M with extreme peak ground acceleration of 0.16 g 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 > 43,500 yr BP that constrains the long-term sedimentation rate to ~ 6 cm/ka. Correlation with the regional magnetic susceptibility stratigraphic record suggests an age of ~ 130,000 yr 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 100,000 years due predominantly to low regional sedimentation rates.