The Garth tsunami is a likely prehistoric tsunami off the Shetland Islands that may have occurred 5,500 years ago (3,500 BCE). Its origin is unknown; impact events, earthquakes, and submarine landslides similar to the Storegga Slide 8,100 years ago (6,100 BCE) have been proposed as factors contributing to the event. Evidence suggests a run-up of more than 10 metres (33 ft) in the Shetland Islands. It probably had great impact on coastal communities in the region; mass burials dating approximately to that time in the Shetland and Orkney Islands have been interpreted to host its fatalities.