Gisborne tsunamis, 1947
At 8.32 a.m. on 26 March 1947, a seemingly minor earthquake jolted the Gisborne area, generating a tsunami that 30 minutes later swamped the coast between Muriwai and Tolaga Bay.
Four people in the hotel near Tatapouri Point, north of Gisborne, spotted an ominous wave offshore and dashed up a nearby hill. Two successive waves drove through the hotel’s ground floor, filling it to the window sills. Many minutes later the receding water sucked small outbuildings out to sea.
At Turihaua, a 10-metre wave bore down on a cottage. Two men outside were swept inland and dumped on the coast road. Two women and a man were trapped in the kitchen of the cottage, which filled to head height with water. Battered by debris-laden water rushing back to the sea, the cottage crumbled. Only the kitchen was left standing.
At Pouawa Beach, the Pouawa River bridge was carried 800 metres upstream. At Te Mahanga Beach the tsunami shifted a house off its piles, and at Murphy’s Beach six hectares of pumpkins disappeared out to sea.
Less than two months later, on 17 May 1947, another offshore earthquake generated a tsunami that hit the coast between Gisborne and Tolaga Bay. At its maximum, north of Gisborne, this wave was about 6 metres high.
No one died in either of the 1947 tsunamis, but the toll could have been high had they struck during summer holidays, when the beaches are crowded.
A wall of water
Staying at Turihaua Point, Donald Tunicliffe witnessed the wave of March 1947:
‘It sounded like a powerful motorbike that was really getting wound up. … I got to my feet with Novena following and led the way out of the door. … A fascinating but horrifying spectacle met our gaze. Approaching the shore, and us, at breakneck speed and roaring like an express train was a wall of dirty coloured water towering to a good 30 feet [9 metres], boiling and curling as it picked up acres of beach sand on its way to engulf us within seconds.’ 1
Chile tsunami, 1960
The most powerful earthquake of the 20th century was of magnitude 9.5, off the coast of Chile on 22 May 1960. It generated a tsunami that killed several thousand in Chile and across the Pacific, including 61 people in Hawaii and 199 in Japan.
In the late evening and early morning of 23 and 24 May, the first of many tsunami waves began arriving at New Zealand’s east coast. The tsunami caused wild fluctuations in the water level along the coast for several days, damaging boats and harbour facilities.
In the North Island, at Napier, waves that reached 4.5 metres above high-tide level damaged a footbridge over the Ahuriri estuary, wrecked many pleasure boats and swept others out to sea. At Scapa Flow, the waves inundated beach homes and boat houses. At a seaside campground at Te Awanga, north of Hastings, eight people were washed out of their tents, and waves battered cabins.
Further north at Whitianga, the waterfront road and the airport were flooded, and a number of small craft were washed out to sea. During later fluctuations, the sea retreated from the shore, exposing the wreck of HMS Buffalo, which had sunk in 1840. Some people ran out to the wreck to collect relics, but were forced to retreat when the sea returned.
At the port of Lyttelton in the South Island, the tsunami came in at 2.7 metres above the tide level of the time, damaging boats and electrical gear. A hotel and several houses were flooded, and 200 sheep drowned.
Several days later, warnings of another possible tsunami from a major aftershock sparked an evacuation of many areas on the New Zealand coast.
Kaikōura tsunami, 2016
The magnitude 7.8 Kaikōura earthquake sequence on 14 November 2016 ruptured several submarine faults and triggered submarine landslides, causing minor tsunami along the east coast of New Zealand. Because of uplift of long stretches of the coast and a low tide, the effects were minor. The maximum height, 6-7 metres, was at Goose Bay, with 2.5 metre waves at Kaikōura and 1.6 metres at Wellington. The tsunami was only one-metre high at Lyttelton, but at Little Pigeon Bay on Banks Peninsula, a three-metre high wave shoved a holiday house off its foundations.