The 2016 Kaikōura earthquake was a 7.8 earthquake in the South Island of New Zealand that occurred two minutes after midnight on 14 November 2016 NZDT (11:02 on 13 November UTC). Ruptures occurred on multiple faults and the earthquake has been described as the "most complex earthquake ever studied". It has been subsequently modelled as having a megathrust component set off by an adjacent rupture on the Humps Fault. It was the second largest earthquake in New Zealand since European settlement.
The earthquake started at about 15 kilometres (9 mi) north-east of Culverden and 60 kilometres (37 mi) south-west of the tourist town of Kaikōura and at a depth of approximately 15 kilometres (9.3 miles). The complex sequence of ruptures lasted about two minutes. The cumulative magnitude of the ruptures was 7.8, with the largest amount of that energy released far to the north of the epicentre.
Over 45,000 insurance claims were received, resulting in a loss of NZ$2.27 billion (US$1.62 billion). There were two deaths, in Kaikōura and Mount Lyford.
Earthquake
A complex sequence of ruptures with a combined magnitude of 7.8 started at 00:02:56 NZDT on 14 November 2016 and lasted approximately two minutes. The hypocentre (the point where the ruptures started) was at a depth of 15 kilometres (9.3 miles). The epicentre (the point on the Earth's surface above the hypocentre) was 15 kilometres (9 mi) north-east of Culverden and 95 km (59 mi) from Christchurch. From the hypocentre associated with the Humps Fault, ruptures ripped northwards at a speed of 2 km/s (1.2 mi/s), over a distance of up to 200 km (120 mi). The largest amount of energy released did not occur at the epicentre, rather 100 km (62 mi) to the north near Seddon. Initial field surveys indicated ruptures on at least six faults, while more detailed studies confirmed ruptures on twenty-five faults. This is considered a world record for the greatest number of faults to rupture in a single earthquake event.
The earthquake was assessed as the "most complex earthquake ever studied" and prompted the reassessment of a number of assumptions about earthquake processes. For example, the likely contribution of underground overpressured fluid to the propagation observed required data collection and reanalysis with new earthquake models not available to initial researchers.
There was motion on the Kekerengu Fault of up to 12.0 m (39.4 ft) ± 0.7 m (2 ft 4 in), movement on the linkage Hundalee Fault of up to 2.5 m (8.2 ft) vertically and horizontally 3.7 m (12 ft), a newly identified fault in Waipapa Bay, as well as minor motion on the Seaward segment of the Hope Fault, and rupture on the Humps Fault and in the Emu Plains area. The offshore continuation of the Kekerengu Fault to the north east, known as the Needles Fault, ruptured as well. NIWA marine geologist Philip Barnes said the Kekerengu–Needles Fault rupture may extend for about 70 km (43 mi), consisting of 36 km (22 mi) on land and 34 km (21 mi) under the sea.
Cape Campbell, at the north-eastern tip of the South Island, moved to the north-north-east by more than two metres – putting it that much closer to the North Island – and rose almost one metre. Kaikōura moved to the north-east by nearly one metre, and rose seventy centimetres. The east coast of the North Island moved west by up to five centimetres, and the Wellington Region moved two to six centimetres to the north. Christchurch moved two centimetres to the south.
Tsunami
The tsunami that followed the Kaikōura earthquake reached a peak height of about 7 metres. The tsunami was found to be highest at Goose Bay, with data indicating a maximum run-up height above tide level at the time of the tsunami of 6.9 m ± 0.3 m. At Oaro, the height was 5.3 m ± 0.3 m. Marine and freshwater flora and fauna were later found scattered across the Oaro River flood plain, extending 250 metres (820 ft) inland from the high tide mark on the day of the survey.
A tsunami estimated at five metres high struck the north-facing Little Pigeon Bay on Banks Peninsula. The bay contained only one building, an unoccupied holiday house that was pushed off its foundations and heavily damaged. In neighbouring Pigeon Bay, the tsunami was observed at about 2 am but caused no damage. In general, tsunami damage along the Kaikōura coast was minor because it happened at mid to low tide, beaches in the area are steep and much of the coastline had been lifted up during the earthquake.
Casualties
Two people died in the earthquake. A man was crushed and died when the historic Elms Farm homestead near Kaikōura collapsed. Two other people were rescued from the rubble of the house, including the man's 100-year-old mother. A woman died in a log house that was damaged at Mount Lyford. Early reports said her cause of death was a heart attack, but an autopsy later indicated that she died from a head injury suffered during the earthquake.
Damage
Road and rail
The earthquake caused "tens of thousands" of landslides. Many major roads were closed in the South Island because of slips and damage to bridges, including State Highway 1 between Picton and Waipara and State Highway 7 between Waipara and Springs Junction (SH 65 turnoff). Most roads were cleared within 24 hours, but SH 1 between Seddon and Cheviot via Kaikōura and the Inland Kaikōura Road were closed for longer. The closure of SH 1, the Inland Kaikōura Road and the Main North Line railway effectively cut off all land routes into Kaikōura. Parts of diversion routes via State Highways 63, 6, 65 and 7 carried four times their usual traffic volume.
On 30 November 2016, the Inland Kaikōura Road, redesignated "Kaikōura Emergency Access Road", was reopened to civilian drivers holding a permit and for restricted times of the day. Twenty-five crews had worked to clear 50 landslips on that highway alone. It reopened unrestricted to all traffic on 19 December 2016.
State Highway 1 south of Kaikōura reopened two days later on 21 December 2016, albeit only during daylight hours. Repair of the highway north of Kaikōura took substantially longer, with the repaired highway opening over a year later on 15 December 2017.
One of the biggest landslides occurred at Ōhau Point, where more than 130,000 m3 of debris covered State Highway 1 and the Main North Line of the South Island Main Trunk Railway, blocking one of the South Island's main transport corridors. The NZ Transport Agency and KiwiRail established the North Canterbury Transport Infrastructure Recovery (NCTIR) alliance in order to reopen the transport route as quickly as possible. Both ends of Tunnel 19 on the South Island Main Trunk through Ōhau Point were blocked by rockfalls which took ten months to clear away. Freight services on the Main North Line resumed on 15 September 2017. The railway line and road were realigned nearer the shore at Ōhau Point. SH 1 previously wound around the slope of the bluff at the point, but it was decided to build an embankment and concrete seawall and reroute the road lower down around the base of Ōhau Point. The former road became a catch bench (a flat area to catch rocks and debris falling down the hillside).
The long term closure of State Highway 1 north of Kaikōura (between Mangamaunu and Clarence) resulted in a detour through the Lewis Pass being the only major route from Picton to Christchurch. This highway had to be upgraded significantly due to this increased usage.
The section of the Main North Line rail link from Picton south to Lake Grassmere reopened on 16 January 2017. Although freight services from Picton through to Christchurch resumed on 15 September 2017, passenger service did not resume until 1 December 2018 due to continued landslides and repair work.
In late 2020 rebuilding and strengthening of the road and rail between Clarence and Oaro was finished, at a cost of NZ$1.25 billion (US$890 million).
Kaikōura
Kaikōura was cut off by road due to landslides, damaged bridges and infrastructure, road subsidence, and the risk of falling debris. The earthquake led to the physical isolation of Kaikōura for some time, which had significant effects in a town reliant on tourism. Some smaller tourism operators were unable to get District Council support or government grants to survive for over a year without visitors. Farmers were unable to transport their produce, and the local fishery was closed due to fear of contaminated runoff from the land.
Mains water supply was mostly restored to Kaikōura township by 19 November, but supply was in a "fragile state" and conservation was necessary. The sewage system was "severely damaged" and unusable.
Kaikōura harbour
The earthquake lifted the seabed around the Kaikōura coastline. At the marina at South Bay, the seabed lifted by more than one metre, leading to vessels resting on rock at low tide. Whale Watch Kaikōura and Encounter Kaikōura suspended their operations. By 31 December 2016, Whale Watch had trialled a modified trailer that could launch its vessel Tohora in the marina, and began whale watching trips again, operating one tour each day with only one boat, and limited to periods around high tide. Whale Watch reported that they were operating at only 20 per cent of their capability, and that there had been a 60 per cent fall in visitor numbers. The Hurunui/Kaikōura Earthquakes Emergency Relief Act 2016 provided a modified resource consent process that enabled a shortened process for consenting works needed to restore the harbour. Excavation work in the harbour began in late December with government funding of $5 million and a subsequent contribution of $1 million from the Kaikōura District Council, Whale Watch and Encounter Kaikōura. The excavation and reconstruction of the harbour was originally expected to take a year, but was completed in nine months, with an official re-opening on 14 November 2017.
Ecological disturbance
Uplift along the coast at Kaikōura (up to 6 metres) exposed the intertidal zone, which resulted in a large-scale die off of many organisms including Durvillaea bull kelp. The loss of Durvillaea kelp caused ecological disturbance, significantly affecting the biodiversity of the local intertidal community. Aerial drone imaging two years after the earthquake indicated that Durvillaea abundance remained low on reefs with significant uplift, but it revealed offshore refuge populations less frequently detected by field researchers. Genomic research sampling of D. antarctica populations before and after the 2016 earthquake indicates that the original populations have managed to survive and are dominating the initial recolonisation process along the newly formed intertidal coastline. However, D. antarctica remains sparse and further change in genetic diversity is possible over the next coming decades.
Pāua were especially affected by the uplift of the Kaikōura coastline because their habitat is close to shore. In the days immediately after the earthquake, volunteers moved between 20,000 and 56,000 kilos of pāua from the uplifted rocks where they were stranded, back into the water. Affected areas were closed to all pāua harvesting after the earthquake to allow the species to recover. Commercial harvesters and divers had their Total Allowable Commercial Catch (TACC) halved, which caused financial pressure for small family-owned businesses. The fishery reopened for three months from December 2021 to February 2022, and after analysis of this period the fishery reopened to recreational and commercial harvesting in 2023.
The Hutton's shearwater (Puffinus huttoni) colony in the Seaward Kaikōura ranges was extensively damaged by the earthquake. Large landslides buried up to 20% of the existing colony areas. Extensive shaking damaged the integrity of many burrows in the remaining shingle and soil tussock-covered habitat used by these alpine nesting seabirds. The birds were at the peak of egg laying in mid-November and with the quake happening at midnight there would have been considerable losses of birds nesting within breeding burrows. The earthquake also buried one of the two boulders remaining inhabited by the eyelash seaweed, with the condition of the other 4 km away being unknown. The species has not been found in the wild since the earthquake, and it may now be extinct.
Wellington
Buildings were damaged in Wellington, some beyond repair. Damage to docks briefly halted ferry traffic across Cook Strait, and container shipping did not resume for over ten months because of damage to the container terminal. Wellington City Council was given special powers to require reports from building owners, and there were doubts about application of the rules. By February 2017, business insurance claims had passed NZ$900 million (US$641 million). The Wellington Region had two thirds (65%) of the total losses, followed by the upper South Island at 25%, Canterbury at 8% and the remaining 2% from elsewhere in the North Island.