Landslides in deep canyons in Cook Strait can set off 10-metre high tsunamis

Landslides in offshore canyons could cause tsunamis more than 10 metres high along parts of the Cook Strait coastline, scientists have calculated.

Niwa and GNS Science researchers spent four years assessing the risk of tsunamis generated by landslides in the Cook Strait Canyon.

It was estimated a 1m landslide-generated tsunami could be expected somewhere along the greater Cook Strait coastline every 140 years, Niwa hydrodynamics scientist Dr Emily Lane said.

A 10m tsunami resulting from a landslide could probably be expected somewhere along the coastline every 2500 years.

As a general rule, the exposed open coasts would have the biggest tsunami. “They pack a punch on the coast but they don’t have as much energy (as earthquake-generated tsunami) to keep on travelling into harbours and bays,” Lane said.