The catastrophic 1855 AD Wellington earthquake is used to predict likely environmental impacts of earlier seismic events (earthquake and tsunami) that have been reported for the Cook Strait region in the period following first human settlement 700 years ago. Environmental changes around Palliser Bay in prehistoric Maori times, inferred from archaeological research, parallel those that occurred in 1855 AD. We consider that devastation caused by earthquake activity and subsequent tsunami, rather than climatic deterioration invoked previously, precipitated the rapid abandonment of the Palliser Bay coast by human communities in the 15th century AD.