THE SOURCE MECHANISM AND NUMERICAL MODELLING OF THE 1953 SUVA TSUNAMI, FIJI

Abstract

A study is presented on the cause of the destructive tsunami that struck Suva City in 1953 following a moderate offshore earthquake (MS 6.75). Alternative earthquake and submarine landslide source mechanisms are modelled using the Geowave tsunami simulation model and compared with observational reports. A simulation using a 60 million cubic metre submarine landslide located at the head of the Suva Canyon, 4 km to the WSW of Suva City reproduces the observed run-up. The simulation shows that high variability in tsunami impact over short coastal distances of Suva are attributable to the complex interplay of wave propagation with the barrier reef system, variable lagoon bathymetry and irregularly shaped coastline. The earthquake tsunami may have been responsible for the observed small “warning” wave, which preceded the destructive tsunami waves initiated by the submarine landslide.