The collapse occurred shortly after 10:30 a.m., when, following weeks of rain, a massive, fast-moving wall of mud and debris crashed down the hillside, destroying 49 homes and killing entire families. One recovery worker said the force of the mudslide caused cars to be “compacted down to about the size of a refrigerator, just smashed to the point where you can hardly tell it was a vehicle,” according to a Reuters report. The debris field from the slide covered a square mile and was estimated to be 80 feet deep in some places. In July 2014, search and rescue workers discovered what was believed to be the last body of the 43 victims killed in the disaster.
Investigators indicated heavy rainfall in the weeks prior to March 22 helped trigger the slide, although they did not blame the disaster on one specific factor. The Oso area has long been prone to mudslides, some dating back thousands of years. Prior to the 2014 incident, a significant slide took place at the same site in 2006, although efforts later were made to reinforce the area. Mudslides, also known as mudflows, are a common type of landslide. Each year in the United States, more than 25 people on average die due to landslides, while thousands more are killed elsewhere around the world. In 1969, Hurricane Camille created flash floods and mudslides that killed an estimated 150 people in Nelson Country, Virginia. In 1985, a landslide set off by heavy rains in Puerto Rico killed some 130 people. In 2013, some 5,700 people in northern India perished as a result of landslides and flash floods caused by monsoon rains.