Question: why was the oso landslide an unusual landslide?
Answer: The Hazel Landslide has a history of instability dating to 1937. Prior to the March 2014 mudslide, the Oso area had heavy rainfall during the previous 45 days, up to 200 percent of normal. ... A national geologist stated the flow of the landslide was extreme because of the extraordinary run-out of mud and debris.