'This is a potential hazard' - Landslides have triggered tsunamis up to 5m in New Zealand lake

A NIWA study shows tsunamis up to 5m have occurred in Lake Tekapo, prompting a warning from the authors.

Dr Joshu Mountjoy, speaking this morning to TVNZ 1's Breakfast today, said tsunamis in lakes are rare, but they do happen.

"Not many people think about these, but there have been a number of examples where large tsunamis have happened in lakes," he said.

"We've seen that there's landslides all around the edges of the lakes and recorded in the lake sediments, and so we've modelled those and we're seeing waves of up to 5m at lots of locations around the shore."

Dr Mountjoy said New Zealand was among countries with dynamic geological landscapes, which have the steep mountains next to lakes required to trigger landslide tsunamis.

"Wakatipu, Wanaka, Lake Taupō - these are subject to these dynamic geological processes and so could have tsunami in them.

"People need to be aware that this is a potential hazard.

"The same thing applies that we advise at the coastline - if it's long and strong, be gone.

"If you feel a really large earthquake, if it's more than a minute long or it's so strong you can't stand up, then move away from the shoreline.

"The warning's going to be natural."

Dr Joshu Mountjoy of NIWA says tsunamis of up to 5m have taken place at Lake Tekapo. Source: Breakfast