2014 Oso mudslide. Aerial photograph from a survey showing the extent of the mudslide of 22 March 2014 that covered 2.5 square kilometres near the rural community of Oso, north-east of Seattle, Washington State, USA. A total of 43 people died here when heavy rain caused this unstable hillside to collapse. The area is prone to landslides, with previous collapses and mudslides dating back to at least 1937. The survey was conducted by the Washington State Department of Transportation, Washington State Department of Natural Resources, USGS, and the Air Support Unit of King County Sheriff's Office. Photographed on 24 March 2014.