On August 14 1868 at 10:15 am (Chatham Islands local date and time), a large-magnitude earthquake struck off the coast of Arica, near the Chile-Peru border. The earthquake generated a large tsunami that was observed throughout the Pacific region. As no tsunami warning system existed for the Pacific at that time, people in areas beyond the earthquake source were generally caught unaware. Almost 15 hours after the earthquake, at 1:00 am on 15 August, an hour before high tide, the largest tsunami waves arrived along the east and north coasts. People woke to a loud roar and water surging through their homes. Ten minutes later, a larger wave hit followed 3–5 minutes later by a third large wave that dragged away everything still standing.
the first great wave rushed in with such force and terrific noise that the very foundation of the deep seemed broken up. In ten minutes more, another wave, more terrible than the former, commenced its work of destruction and after a like interval, the third and last completed the catastrophe. Indeed, the full wrath of the ocean seemed to battle with the island in fierce resolve to submerge it… The third wave, which came rolling in with most awful grandeur and thousand-fold power, bearing down outbuildings and stout old akeakes [native tree, Olearia traversiorum], which broke and cracked beneath its fury like matchwood, carrying away young cattle, and scattering the debris of the ruins far away…
Hawkes Bay Herald 1868
The entire Chatham Islands coastline was affected. The north and east coasts experienced waves up to six metres that flooded up to six kilometers inland. Waitangi, Te One and the South Coast experienced waves of 2.4–4.6 metres.
Tupuangi, Te Raki and Waitangi West experienced the greatest effects of the tsunami. The entire kāinga at Tupuangi, where approximately 70 people lived, was destroyed. Whare were smashed, vegetation was destroyed and sand, boulders and seaweed covered the ground.
Māori oral histories reveal three whānau were washed away with their whare and drowned.
People who ran to high ground survived but were left with nothing. The once flourishing settlement was abandoned and many people returned to ancestral lands in Taranaki (on mainland Aotearoa-New Zealand) soon after.
The rest of the island fared little better. A man drowned at Waitangi West while trying to save a fishing boat. Many houses were destroyed and washed away and the Pā at Waitangi was damaged. Boats and bridges were damaged or washed away, beaches were covered in debris and sand dunes were eroded. Abnormal waves, surges and strong currents continued over the following 24 hours even as people cleaned up the mess left behind the tsunami.
Tsunami waves affected Aotearoa-New Zealand one to two hours after arrival in the Chatham Islands. Several people were nearly swept away, many boats were damaged and some homes, roads and fences were destroyed, particularly around Banks Peninsula near Christchurch.
In Lyttelton Harbour, the tsunami had a trough-to-peak height of around 7.6 metres. Tsunami waves and surges were observed over the next two days along the east coast from Maunganui in the north to Bluff in the south as well as in places along the West Coast region.
From The Star, Christchurch, 15 August 1868:
“EXTRAORDINARY TIDAL WAVE.
“The town of Lyttelton was this morning thrown into a state of the greatest excitement owing to a most extraordinary convulsion of nature. At present it is impossible to say what it is, whether a submarine eruption or a tidal wave, but the damage done to the vessels is considerable. We learn the following particulars from Mr Webb, nightwatchman on the railway.
“He states that at four this morning, on going his rounds, he noticed that the barque John Knox was lying on her starboard broadside, and her yards were nearly touching the screw-pile jetty alongside which she was discharging her cargo. He immediately gave an alarm, and aroused Captain Jenkins, who came on deck; he thought the coals in the vessel had shifted, but on looking over the side he saw that the harbour, from the wharf to Officers’ Point, was quite dry, and that all the boats and vessels were high and dry; he called Webb’s attention to this, and it was a fact that the harbour was empty.
“In a few minutes their attention was directed to a noise resembling thunder, coming from off Officers’ Point. On looking, they saw an immense wave coming along the harbour with fearful velocity, and in a few minutes it was surging round tho vessels, tearing them from the different wharves and breaking the warps like twine. It caught the barque John Knox, and drove her against the screw-pile jetty, carrying away her starboard quarter, and snapping her mooring chain and hawsers which held her to the wharf. The ketch Margaret, lying on the beach, had her warps carried away. The wave caught her on the rebound, and she was.carried into the harbour, fouling the Annie Brown, schooner, and carrying away her bulwarks, stanchions, and mast, and doing damage to the schooner; she is in a sad state.
“The schooner Jeannie Duncan lying at the Hallway wharf recievcd serious damage; the Novelty, steamer, lying alongside of her carried away by collision, her bullwarks and stanchions from fore to main rigging, and her boat is broken in half.
“For some hours the tide kept rising and falling, sometimes three foot in five minutes. At half-past nine another small roller came in, and again caught the John Knox, which was at that time on the mud. In a few minutes the warps parted, and the vessel swung round fortunately clear of the wharf.
“At eleven o’clock, the steamer Taranaki came up harbour. As she stopped at the heads for some time it was feared there might be something wrong. It turned out however, she stopped to pick up part of a wreck of some vessel. The portion secured was a hatch covering, evidently belonging to a large vessel; she also passed a full-rigged mast outside the heads. Captain Francis informs us there were no signs of any eruption during the passage. We learn that the ketch Georgina has been wrecked in Rhodes’ Bay.
“The following is Captain Jenkins’ report;
“At 3.30 I heard a noise. The ship went down on her beam ends. With difficulty I got on deck and found the ship lying with her yard-arm on the wharf. I could not conceive what was the matter, when I heard a noise like the rushing of a great body of water, or a strong wind. I looked out into the harbour. It was all dry as far as the breakwater, and a wave rolling in about 8 feet high; it came up against the ship with great force. A few minutes afterwards, it rebounded and caught tho ship’s bow, carrying away two parts of an 8 inch warp and the best bower cable, which was shackled on to the wharf, dragging the anchor home with 60 fathoms cable. In 15 or 20 minutes after the wave came in, the water had been within three foot of the top of the wharf. In less than half an hour the ship was dry again. It rushed in and out at intervals until 10 a.m., when another rush ran out, and broke three parts of the stone warp, the ship swinging round again. Capt. Gibson sent his boat and crew and the Government warp, making it fast to the buoy and passing both ends on board ship; by so doing the ship was kept head and stern to the current as it ran in and out. Damage done — Starboard quarter knocked in. She was bounded up against the wharf by the tidal wave.”