Thawing permafrost in Arctic hillsides and shorelines causes slumps known as mega retrogressive thaw slumps.Up to 90% of Canada's Arctic slumps recur in the same location as previous slumps.Seawater penetration destabilizes the permafrost and contributes to the formation of slumps.Factors such as changes in ground cover and active slumps contribute to the warming of underlying permafrost, resulting in more slumps.