In the last 190 years a total of 39 tsunamis affecting Samoa have been
recorded. Many of them caused by earthquakes occurring along the Tonga
Trench, which is only 150 km away from the islands. In 1917, an
earthquake with a magnitude of 8.3 caused a disastrous tsunami in Samoa.
Even though it was a major event, historical records are scarce and
little is known about the event. In order to overcome this lack of data,
this work has modelled the aspects of the 1917 tsunami event, using
available historical records. The tsunami model used an earthquake
initiation, propagation along the Tonga Trench and generated inundation
footprints for the islands of Samoa. Then using this model output, the
impact in present-day Samoa was determined to estimate the likely
exposure and damage to buildings within the inundation zone. The study
identified a number of inconsistencies between the inundation zone and
the anecdotal evidence recorded at the time of the event. In addition,
discrepancies were identified between the model and the records from
tide gauges in Apia harbour at the time. These recorded a fluctuation of
the sea five minutes after the 1917 earthquake.