Parts of the West Coast of the South Island received a tsunami wave over one metre high as a result of the Gizo (Solomon Islands) tsunami.

Official sea-level gauge results from NIWA show the highest wave height of 1.1 metres occurred at Charleston, near Westport at 20:10 on Monday 2 April (NZST). "Fortunately, this wave occurred around mid-tide on the West Coast," says Dr Rob Bell of the National Institute of Water & Atmospheric Research (NIWA).

Well over a year ago NIWA recognised the possibility of the Solomon Islands as a possible northern source for substantial tsunamis along the west coast of New Zealand. As part of a consultancy project for several regional councils, NIWA scientists, using their RiCOM model, looked at a variety of tsunami scenarios based upon large magnitude earthquakes from the same area where the latest earthquake occurred.

NIWA’s computer model predictions of wave height, areas most likely to record the largest waves, and arrival times, matched very well with what actually happened with the Gizo tsunami. The model predicted that the West Coast around Westport was likely to get the highest waves; and the modelled arrival times – at least one hour later than projected by the Pacific Tsunami Warning Centre warning bulletin – were correct. On Monday (2 April), NIWA scientists kept in close contact with the Ministry of Civil Defence & Emergency Management, and other experts, to ensure the model predictions were clearly communicated.