Paper Number 24 Earthquake and tsunami losses from major earthquakes affecting the Wellington Region

Zealand”. The findings of this report surprised many- for a 500-year return period event, forecasts of property damage ranged from $12 to 21 billion. These values were multiples of most estimates of earthquake shaking damage. Recognising the importance of the findings, Benfield commissioned GNS to advance the research using state-of-the-art modelling techniques. The specific aim was to model the combined shaking and tsunami losses from large earthquakes near Wellington. The work required significant original research on potential tsunami sources, newly compiled elevation and bathymetry data, experience with the recently developed Australian ANUGA tsunami wave propagation model, a detailed building assets model, and a new assessment of tsunami damage to buildings. We modelled tsunamigenic earthquakes on the Wellington Fault (the source of the present earthquake PML), the Wairarapa Fault (a historic tsunami source, second largest earthquake shaking loss), the BooBoo Fault (a large fault in Cook Strait) and the Subduction Zone (a major tsunami source). The results showed that the Wellington Fault earthquake still represents a reasonable benchmark for risk assessment purposes, with the combined earthquake and tsunami losses generated for four key earthquake scenarios either adding little to the Wellington event itself, or accumulating to significantly less than that earthquake on a stand alone basis.