Long-runout landslides with longitudinal ridges: are these catastrophic events related to climate change phenomena?

Long-runout landslides with longitudinal ridges are amongst the most catastrophic type of mass movements and the least understood. Only ancient (i.e., ~60 ka/7 ka) long-runout landslides with longitudinal ridges are preserved in the terrestrial geomorphological record. This geomorphological record is critical to understanding where, when, and how these catastrophic events occurred, thus critical to addressing a key question in hazard assessment: how likely events of similar magnitude to those of the past are likely to occur in the future?The RIDGES project aims to answer this important question: are long-runout landslides with longitudinal ridges related to climate change phenomena, i.e., deglaciation and permafrost degradation? This project will study well-preserved long-runout landslides with longitudinal ridges in Iceland, a unique region for its high spatial density of well-preserved long-runout landslides with and without longitudinal ridges, not seen anywhere else on Earth. By using an original combination of interdisciplinary methods and a multi-scale approach to understand the chronology and the complexity of large slope instability in deglaciated areas, which remain major geomorphological issues worldwide, RIDGES will directly reconstruct paleo-climatic and paleo-environmental conditions during which landslides with longitudinal ridges formed in Iceland.The results from RIDGES will help better understanding whether the occurrence of catastrophic landslides with longitudinal ridges is related to climate change phenomena. If a correlation is found, it will help mitigating the risks associated with mass movements in rapidly deglaciating regions due to climate change, such as Greenland and Alaska.