Fish left stranded inland by the tsunami in March, 1947. Photo: Tairawhiti Museum
"It was the same froth, like you get on beer. It was sort of sizzling." A tsunami was imminent, and Tilly Smith knew it.
The 10-year-old Brit became famous for saving the lives of hundreds of people on a Thai beach 20 years ago.
Having just learned about tsunamis in school, she was one of few people to recognise the warning signs of the devastating wave that struck moments later on Boxing Day, 2004.
The Indian Ocean tsunami, which killed more than 200,000 people, was a flashpoint that experts said forever-changed New Zealand's emergency preparedness.
But according to distinguished professor of disaster management David Johnston the so-called 'wake-up call' had arrived on Aotearoa's shores not once but twice in the decades prior - the country did a few things in response then "went back to sleep".
Johnston, who's interested in human response to natural disasters, has been researching New Zealand's lesser-known tsunamis - digging through historic first-person accounts in a bid to raise awareness and encourage preparedness for future mega-waves.
He labels two major tsunami swamping New Zealand's east coast, decades before 2004, as "missed opportunities" for disaster management.
Massive waves strike New Zealand blind
A four-roomed house at Turihaua Point was filled head-high with water in the March 1947 tsunami. Photo: Tairawhiti Museum
On 22 May 1960, a 9.5 magnitude earthquake - the largest captured on instruments - triggered a tsunami that killed thousands in Chile, as well as dozens in Hawai'i and Japan as it swept across the Pacific.
Hours later it slammed into the east coast of New Zealand.
"It struck New Zealand blind," Johnston said.
"It hit most of the east coast of the North and South Islands, inundating properties in Napier, Gisborne, and Lyttelton (and) caused considerable damage.
"No loss of life, but a higher tide would most likely have led to multiple fatalities," he said.
"So a bit of luck, that as a nation, we dodged it. Not because of our preparedness, but because of the tide."
He said an aftershock three days later triggered evacuations but no tsunami came.
The 1960 tsunami was the impetus to set up the Pacific Tsunami Warning Center (extending the warning system beyond the United States), but in New Zealand, "We did a few things and then went back to sleep for a period of time", Johnston said.
"After the Indian Ocean tsunami there were flashbacks to that (1960) event and realising as a nation we needed to do more."
'You had seaweed in the powerlines'
Ben Green and Gisborne's disaster co-ordination system. Photo: Supplied
However, it wasn't the first tsunami the country forgot. Thirteen years earlier, in 1947, Tairāwhiti-Gisborne was hit by not one, but two tsunamis.
Again, there were no fatalities, and again experts put that down to luck.
The region's Civil Defence and Emergency Management group manager Ben Green said eye-witness accounts put the waves at about 12m high.
"You've had people end up on the roof, and people sitting in their kitchen and next thing you know you've got walls of water coming through."
The first wave was triggered by a 7.0 magnitude 'slow-slip' earthquake, 70km south-east of Gisborne along the Hikurangi plate boundary.
The tsunami it generated was the largest in New Zealand's recorded history, crashing into 115km of coastline on 26 March, 1947.
Photo: Tairawhiti Museum
The wave pushed a 16m wooden bridge over the Pouawa River 800m inland, and swept the home of the Hall family off its foundations, demolishing everything but the kitchen, where three people became trapped with water rising to head height.
An account from someone living at the Tatapōuri Hotel, said their dad "took one look (at the ocean) and called out to Mum and me to run for our lives up the hill behind the hotel".
"What an awesome sight to be able to stand well out of danger and watch first one, then another tsunami race across the ocean and smash onto the land."
The 1947 March tsunami flooded the Tatapōuri Hotel. Photo: Tairawhiti Museum
Green said it was surprising there were no fatalities.
A second earthquake, 6.9 in magnitude, struck 30km further north on 17 May, sending another tsunami into the coast.
It's thought to be bigger then the March tsunami, with waves reaching 4-5m above sea level at Tolaga Bay, but because it happened on a "stormy winter night" there are fewer eye-witness accounts.
While major incidents at the time - and likely still would be if the waves had hit during the busy summer - Green said they were now largely "consigned to the memory banks".
"There would be a whole lot of people who aren't aware, that that whole area of coastline … you had seaweed in the powerlines."
And the threat of a repeat is very real, he said.
'The big one' not a case of if, but when
Recent studies suggest there's a 26 percent chance of a "mega-thrust" earthquake along the Hikurangi subduction zone - 8.0 magnitude or larger - in the next 50 years.
Subduction earthquakes were behind both the 2004 Indian Ocean tsunami, and the disaster in Japan seven years later.
GNS principal scientist and lead for natural hazards and risks Graham Leonard said a major rupture along the Hikurangi fault falls outside of written human history, which was short.
But said knowledge of the plate boundary and geological record meant "it's totally possible ... and we need to be ready for it. Because those waves are big".
As emergency response manager, Green said they plan for the worst case scenario, which suggests Gisborne - with its population of 38,000 - would be inundated by a series of mega-waves within half an hour of a Hikurangi rupture.
"It's something that if we don't see in our lifetime, our next generation will see an iteration of."
Green said the number-one focus was raising public awareness.
A potential Hikurangi rupture has been a core part of the National Emergency Management Agency's disaster planning in recent years with a "catastrophic handbook" one of the outcomes on how to respond to the "worst of the worst".
In Tairawhiti, international and national experts have held public presentations on the plate's earthquake and tsunami hazard and in the past month, civil defence has unveiled a major desalination unit and new communications technology that could be a lifeline in the days following a disaster.
Green said national campaigns such as the 'shake-out' and tsunami hikoi were a good annual reminder, and encouraged people to familiarise themselves with tsunami evacuation and inundation maps.
He hopes Johnston's project will also prompt the public to prepare.
Johnston, and many others, will be digging into the archives of the 1947 tsunami over the next year to better understand what exactly happened.
"The fact is many people who saw the tsunami, or were impacted, did report feeling the shake before its arrival and many saw the wave and could hear the wave coming in.
"Many of the recollections are tales of what we could expect to see, should we have future earthquakes and tsunami."
The purpose was to increase people's understanding of the environment and the natural cues that might lead to such a disaster, he said, citing the "famous story about the UK school girl" Tilly Smith.
Stories are powerful, and while it's possible to borrow them from overseas, Johnston said there was something about a homegrown tale - "from someone, from your community, even if it's in the past, in the place that you live", that lands differently.
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