Observations and modelling of tsunami currents at the port of Tauranga, New Zealand

The March 11, 2011 Tohoku tsunami was recorded on five separate water level gauges and a current meter at the Port of Tauranga, New Zealand. As such it represents one of the most comprehensive instrumental data sets of a far-field tsunami affecting a major commercial port. In this paper we present a preliminary analysis of the measured current data, exploring the effect of tidal activity on the tsunami signal. We then model the tsunami in Tauranga using two numerical models; the MOST tsunami model using the ComMIT modelling framework, which relies in part on a database of pre-computed tsunami simulations, and the GeoClaw numerical model, using adaptive mesh refinement for the full simulation. Model results are compared in terms of their relative accuracy to the measured data as well other factors such as model run time, computational demand, model set up and ease of use. The results of this study will highlight the relative strengths between database driven and direct simulation approaches for the real time assessment of far field tsunamis in ports and harbours around the world.