New Zealand’s national emergency agency has confirmed that a large landslide tsunami in Milford Sound could be survived by only a tiny fraction of the people inside the fiord at the time, and it is now spending the next two years trying to understand the danger in far greater detail.
The warning came during a parliamentary scrutiny hearing on Wednesday, where the National Emergency Management Agency was questioned about one of the country’s most alarming natural hazards. As RNZ reported, chief executive Dave Gawn told the committee that a 2024 estimate of the likely survival rate had not improved. He said the scientific evidence pointed to a survival rate of only about four to five percent if a major landslide were to set off a wave in the narrow sound.
Gawn described the situation as a real concern and said it ranked as one of the agency’s biggest risks. The problem, he explained, is not only the size of a possible wave but the lack of escape routes for the thousands of people who gather at the head of the fiord on a busy day. With sheer rock walls rising straight out of deep water on either side, there is almost nowhere for visitors to reach high ground quickly.
Milford Sound, known in te reo Maori as Piopiotahi, is one of the most visited places in the country, drawing cruise passengers, day trippers, kayakers and walkers throughout the year. On a typical busy day around 4,000 people can be present at once, packed into a small area around the wharf, the cruise terminals and the road that feeds in from the Homer Tunnel. That concentration of people in a confined space is exactly what makes the hazard so serious.
The geology of the fiord adds to the worry. Around 40 percent of the floor of the sound is already covered in the debris of past landslides, a record of how often the steep slopes have given way over thousands of years. Researchers have calculated that a strong earthquake in the region carries a high probability of shaking loose another major slide, and a slide of that size dropping into deep, enclosed water is precisely the recipe for a locally generated tsunami that would strike within minutes.
Independent research has put the potential toll into stark figures. A study published in the journal Scientific Reports modelled an average event at Milford Sound and estimated that around 1,006 people would be exposed to the hazard, with about 750 of them likely to die. The same body of work has suggested the landslide tsunami risk at Milford Sound is many times higher than the danger that existed at Whakaari White Island, where an eruption in 2019 killed 22 people. The comparison has stuck in the public mind because it points to a known, mapped hazard rather than a freak event.
What makes Milford Sound so difficult to manage is the very thing that makes it spectacular. A tsunami warning system that works well on an open coast relies on people moving inland and uphill, but in a steep walled fiord there is no inland to move to. Minutes would matter, and the modelling shows that even small differences in how quickly people could move would change the number of lives lost. That is why the agency has been so blunt about the lack of egress routes from the danger zones.
The new spending is aimed at closing the gaps in that picture. The Milford Sound Piopiotahi tsunami, landslide and inundation modelling project received around $206,000 from the Civil Defence Emergency Management Resilience Fund for 2025 and 2026, part of a wider round of grants the agency says will make New Zealand safer. The follow up work, carried out with Earth Sciences New Zealand, Southland tourism interests and the Department of Conservation, is meant to map how a wave would actually behave inside the sound, which areas would be hit hardest and how much time anyone would realistically have.
At the hearing the politics of how far to go was also on display. Emergency Management and Recovery Minister Mark Mitchell signalled that the government did not want to over manage the risk, wary of shutting down or heavily restricting one of the South Island’s great drawcards. New Zealand First MP Andy Foster took a more cautious line, suggesting that overnight accommodation in particular added to the danger and that further development should be approached carefully. Gawn told the committee it was absolutely critical not to do anything that would intensify the risk while the research was still being completed, a polite way of saying that more beds and more buildings in the wrong place could make a bad scenario worse.
For now the message from the agency is that the science has not changed and the danger is real, but the detail needed to plan a proper response is still being gathered. The Otago Daily Times reported the same blunt assessment from the hearing, underlining that a fiord which feels like one of the safest and most serene places in the country sits on top of one of its sharpest natural hazards. Visitors are not being told to stay away, but the people charged with planning for the worst are being unusually frank about how little room there would be to escape.
What do you think the right balance is between protecting one of New Zealand’s most loved destinations and keeping visitors safe? Share your thoughts in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
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