Tsunamis can cause catastrophic impacts at the coastline. Australia’s NW continental margin displays abundant massive slope-failure deposits, but there is little evidence of associated coastal tsunami deposits. Here we report on investigations of an exposed field of cemented dunes and associated conglomero-breccias, located on Barrow Island. Preliminary OSL dating indicates that these deposits formed when relative sea level was around 30 to 50 m below present. If the deposits can be interpreted as having been formed by a mega-tsunami, then it was a very significant event that ran inland several km and achieved a maximum run-up of several tens of metres. A similar event today would directly impact thousands of people, multiple ports, and industrial facilities worth many billions of dollars, as well as impacting many unique ecological and cultural resources.
