NEMA investing in new research about dangers if tsunami hits Milford Sound

3:17 pm today

Photo: 123rf

MPs have been told the very low rate of survival estimated if a landslide tsunami hits Milford Sound remains the case but the chase is on to improve understanding of the risks.

The National Emergency Management Agency, NEMA, told a scrutiny hearing at parliament on Wednesday morning it was a big risk and it was getting new research done.

Chief executive Dave Gawn said an estimate made in 2024 has not budged in part because it is hard to find safe zones for up to 4000 visitors at any one time in the narrow sound, should a big landslide set off a tsunami.

"That scientific evidence that came out that said, actually, as we understand it now, that's probably only about four to five percent survival rate of that is real concern and that's why we're really chasing this hard," Gawn told MPs.

NEMA was about to fund follow-up, more detailed research over the next two years "to understand in far greater granularity ... than we do at the moment".

It took time to understand how the waves would behave and impact the shore.

"It is, I think, one of our biggest risks."

The research was with Earth Sciences NZ, Southland tourism and the Department of Conservation.

Also, they had put up alert boards such as at Homer Tunnel and other tourist education.

"We're certainly not just sitting on our hands."

But asked if that work had upped the survivability estimate, Gawn said, "No".

"The reality is if you've got that many people and the lack of egress routes from the danger zones in terms of being able to get up high in something that is very, very channelled, is of real concern."

Gawn had been asked for any update on the 2024 research that said 3500 could die.

About 40 percent of the base of Milford Sound is covered in landslide deposits. A quake in the fiord had a 44 percent chance of triggering another landslide, the 2024 research said.

Gawn said what the upcoming research would mean for how to manage the risk was the next stage.

NZ First MP Andy Foster said overnight accommodation at Milford seemed to present a real risk and suggested it might be a case for testing the notion of "what to put where" and not intensifying the risk with by building any more, like councils faced in flood zones.

Gawn said it was "absolutely critical" not to intensify the risk.

However, Emergency Management and Recovery Minister Mark Mitchell said the government did not want to over-manage risk.

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