Better picture emerges of tsunami impact on Christchurch

New computer modelling paints a clearer picture of the flooding Christchurch coastlines could see from a large distant source tsunami if sea levels continue to rise with climate change.

The modelling was done by NIWA at Christchurch City Council’s request as part of a Multi-Hazard Analysis project aimed at helping the Council make decisions on long-term floodplain management strategies for the lower reaches of the Avon, Heathcote and Styx rivers and Sumner.

A network of tsunami warning sirens is located along the Christchurch coastline.

The computer modelling looks at the potential flooding from distant source tsunamis triggered by either a magnitude 9.28 earthquake (an event predicted to happen on average once in 500 years) or a magnitude 9.49 earthquake (a one in 2500 year event) in Peru, South America.

It considers different sea-level rise scenarios – ranging from 19cm to 1.06 metres – for the next 50 to 100 years.

According to the modelling, both distant source tsunami scenarios will result in major inundation in Christchurch, which, as expected, will worsen with the higher sea-level scenarios.

Read a report on the findings