Bedrock Iceland Landslides: Dr. Adam Booth

Permafrost and bedrock structure controlled the location and timing of catastrophic bedrock landslides in northern Iceland throughout the Holocene

Large, long run-out, bedrock landslides are widespread in the glacially-incised valleys of northern Iceland, but little is known about why they are clustered in specific locations and when the occurred. In this study, 667 such landslides were mapped and patterns analyzed in space and time to infer their preconditioning and triggering mechanisms. The landslides cluster in space just below the elevation of permafrost and near major sedimentary and volcanic structures. Based on landslide deposit surface roughness, an effective proxy for age, most landslides occurred in the early Holocene, when climate was warmer, and permafrost was largely absent. The findings imply that peak landslide frequency did not occur immediately following the deglaciation, as often assumed in glacial debuttressing models, but instead was controlled by subsequent climatic trends and inherited bedrock properties at least thousands of years later. Although landslide frequency has likely decreased toward the present, modern warming is degrading permafrost in Iceland and could potentially rejuvenate landslide activity.

Dr. Adam Booth is an associate professor in the Department of Geology at Portland State University, where he has worked since 2013. He has a B.S. degree in Physics and a PhD in Geology, and uses tools from both disciplines as a quantitative geomorphologist interested in landslides and how they interact with broader natural systems at the Earth's surface. He uses a combination of numerical modeling, fieldwork, and remote sensing data analysis to gain fundamental understandings of landslide mechanics and landscape evolution over a full range of spatial and temporal scales.