Estimating the source of a 3500–4500 year old tsunami in the South Pacific region based upon boulder transport modelling

Abstract Tsunami-transported boulders lie scattered across Okawa Point on Chatham Island, Aotearoa-New Zealand. These boulders, weighing up to 117 t, are distributed inland from coastal storm ridges, and are reported to have been transported by a tsunami 3500–4500 years ago. However, the origin of the tsunami responsible for this boulder scatter is unclear. In this study, boulder transport modelling shows that tsunamis associated with the 1960 CE Chile (Mw 9.5), 2009 CE Samoa (Mw 8.1), and 1865