2016 Kaikoura earthquake

2016 Kaikoura earthquake

Date	14 November 2016
Origin time	00:02:56 NZDT
Magnitude	7.8 Mw[1][2]
Depth	15 km (9 miles)
Epicenter	42°45′25″S 173°04′37″E / 42.757°S 173.077°E / -42.757; 173.077Coordinates: 42°45′25″S 173°04′37″E / 42.757°S 173.077°E / -42.757; 173.077 15 km (9 miles) north-east of Culverden
Areas affected	New Zealand
Max. intensity	IX (Violent)[1]
Tsunami	Yes
Aftershocks	17,492[3] (as of 20 June 2017)
Casualties	2 dead[4] 57 treated for injuries[5]

Map of Kaikoura earthquakes

USGS ShakeMap for the event

The 2016 Kaikoura earthquake was a magnitude 7.8 (M_w) 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).^[1]

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 Kaikoura and at a depth of approximately 15 kilometres (9 mi).^[2][6][7][8] Ruptures occurred on multiple fault lines in a complex sequence that lasted for about two minutes.^[9] The cumulative magnitude of the ruptures was 7.8, with the largest amount of that energy released far to the north of the epicentre.^[10]

The large magnitude of the quake is second to only one New Zealand earthquake since European settlement of the country.^[11] Over $900 million in insurance claims were received.^[12] There were two deaths, in Kaikoura and Mount Lyford.^[4][13]

Earthquake

Satellite radar image showing ground motion effects during the 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.^[9] The hypocentre (the point where the ruptures started) was at a depth of 15 kilometres (9 mi). 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.^[2][13][14] From the hypocentre, ruptures ripped northwards at a speed of 2 km per second, over a distance of up to 200 km (124 mi). The largest amount of energy released did not occur at the epicentre, rather 100 km (62 mi) to the north near Seddon.^[15] Field surveys indicate ruptures on at least six faults.^[15][16] The earthquake has been assessed as the 'most complex earthquake ever studied' and has meant the reassessment of a number of assumptions about earthquake processes.^[17]

There was motion on the Kekerengu Fault of up to 10 m (33 ft), movement on the Hundalee Fault, a newly identified fault in Waipapa Bay, as well as minor motion on the Seaward segment of the Hope Fault,^[18] and rupture on the Humps Fault and in the Emu Plains area.^[16] The offshore continuation of the Kekerengu Fault to the north east, known as the Needles Fault, ruptured as well. NIWA marine geologist Dr Philip Barnes said the length of 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.^[19]

Cape Campbell, at the north-eastern tip of the South Island, moved to the north-northeast by more than two metres – putting it that much closer to the North Island – and rose almost one metre. Kaikoura moved to the northeast 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.^[15]

Tsunami

The tsunami that followed the Kaikoura 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.^[20]

Immediately after the earthquake, the tide level at the Kaikoura tide gauge started dropping. Over 25 minutes, it dropped about 2.5 m, a classic warning sign of a tsunami. During the next 15 minutes, the water level rose from its lowest level by about 4 m. That was followed by a series of waves over several hours. The water level at the Kaikoura gauge rose 2.5 m higher than it would have been. This was made up of a 1.5 m rise measured on the gauge, and a rise of about 1 m of the gauge itself, as the seabed and surrounding land rose by that amount. Some other tide gauges that recorded the tsunami were in Wellington Harbour, Castlepoint, Christchurch, and the Chatham Islands.^[20]

A tsunami estimated at five metres high struck the north-facing Little Pigeon Bay on Banks Peninsula.^[21] The bay contained only one building, an unoccupied holiday house that was pushed off its foundations and heavily damaged.^[22] In neighbouring Pigeon Bay, the tsunami was observed at about 2 am but caused no damage.^[21]

Casualties and damage

Kaikoura and North Canterbury

The Elms homestead, pictured here in 2012, collapsed during the earthquake, killing one person.

Two people died in the earthquake. A man was crushed and died when the historic Elms Farm homestead near Kaikoura collapsed. Two other people were rescued from the rubble of the house, including the man's 100-year-old mother.^[23] 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 it was a head injury suffered during the earthquake.^[24]

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 Kaikoura and the Inland Kaikoura Road remained closed.^[25] The closure of SH1, the Inland Kaikoura Road and the Main North Line railway effectively cut off all land routes into Kaikoura.^[26][27]

As of the morning of 19 November, Kaikoura remained cut off by road due to landslides, damaged bridges and infrastructure, road subsidence, and the risk of falling debris.^[28] The NZ Transport Agency said that State Highway 1 would take months to repair, while repairs to the rail line, a key freight connection between Wellington and Christchurch, were likely to take more than a year.^[29] Parts of the diversion route via State Highways 63, 6, 65 and 7 were experiencing four times their usual traffic volume.^[30]

Mains water supply was mostly restored to Kaikoura township by 19 November, but supply was in a "fragile state" and conservation was necessary. The sewage system was "severely damaged" and unusable.^[31]

On 30 November 2016, the Inland Kaikoura Road, redesignated "Kaikoura 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.^[32] It reopened unrestricted to all traffic on 19 December 2016.

State Highway 1 south of Kaikoura reopened two days later on 21 December 2016, albeit only during daylight hours.^[33] As of April 2017, long term closure of State Highway 1 north of Kaikoura (between Mangamaunu and Clarence)^[34] has resulted in a detour through the Lewis Pass being the only major route from Picton to Christchurch. This highway has had to be upgraded significantly due to this increased usage.^[35]

The section of the Main North Line rail link from Picton south to Lake Grassmere reopened on 16 January 2017.^[36]

Wellington

Demolition of the damaged cinema and parking building at Queensgate Shopping Centre, Lower Hutt, on 6 December 2016

In the city of Wellington, buildings were damaged, several beyond repair.^[4] Damage to docks briefly halted ferry traffic across Cook Strait;^[4] more significantly, container shipping did not resume for over ten months.^[37] The Council was given special powers to require reports from building owners,^[38][39] and there were doubts about application of the rules.^[40] Several buildings were closed temporarily because of doubts about stairwells.^[41][42]

A 54-year-old nine-storey office block at 61 Molesworth Street was demolished during December 2016, after fears that it could collapse.^[43][44] The Reading Cinema parking building off Courtenay Place was also damaged and was demolished during January 2017. Both building failures resulted in a section of the adjacent street (Molesworth Street and Tory Street) being closed off for a period.^[45]

By February 2017, business insurance claims had passed NZ$900 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 other North Island claims.^[12]

In 2016 and 2017 it was decided that several other buildings would be demolished, not repaired: the Figaro Block of the Malvina Major Retirement Village in Burma Road, Johnsonville,^[46] and the eleven year old, seven-storey NZDF headquarters.^[47]

In Lower Hutt, a cinema complex and part of the carpark in the Queensgate Shopping Centre was deemed unsafe and was demolished.^[48] At Ava railway station, one of the pedestrian access ramps was damaged and was removed during the weekend of 17 and 18 December, leaving the station without wheelchair access until such time as the ramp can be replaced.^[49]

Christchurch

One house in the coastal suburb of New Brighton in Christchurch was reportedly looted after the occupants left because of tsunami risk.^[50]

Regional effects

Schools and universities across the region were told to remain closed until the situation could be assessed,^[51][52] affecting the end-of-year NCEA examinations for secondary school students.^[53]

Response

Prime Minister John Key surveyed the damage from the air and later described the scenes as "utter devastation" and estimated that reconstruction would take months and cost billions of dollars.^[54]

The New Zealand Defence Force dispatched five Royal New Zealand Air Force helicopters (four NH90s and one Agusta A109), a P-3 Orion and a C-130 Hercules to survey and provide essential emergency supplies to the most-severely affected areas around Kaikoura. Kaikoura Aerodrome was too small to take larger multi-engine aircraft so landing was limited to helicopters and small aircraft. The Royal New Zealand Navy's multi-role vessel HMNZS Canterbury and off-shore patrol vessel HMNZS Wellington were deployed to Kaikoura to provide aid supplies and evacuate people.^[55] HMCS Vancouver, HMAS Darwin and USS Sampson, in New Zealand waters for the RNZN's 75th birthday celebrations in Auckland, were redirected by their respective governments to assist.^[56] A United States Navy P-3 Orion of VP-47 and two Japan Maritime Self-Defense Force Kawasaki P-1s, also visiting RNZAF Base Whenuapai for the RNZN 75th anniversary events,^[57] were deployed to assist.^[58] The New Zealand Defence Force also deployed HMNZS Te Kaha^[59] and HMNZS Endeavour^[60] to support the operation.

The New Zealand Fire Service dispatched urban search and rescue teams to Wellington and Kaikoura. Paramedics were also dispatched from St John.^[51]

Baggage of evacuees being unloaded off HMNZS Canterbury

Nearly 200 people had been airlifted out of Kaikoura by late evening on 15 November, with about 1,000 still to be evacuated on the following morning.^[61] Stranded tourists with health issues and travel plans were put on a flight priority list.^[62] HMNZS Canterbury arrived in Kaikoura on 16 November and transported about 450 evacuees, 4 dogs, and 7 tonnes of luggage to Lyttelton, arriving early the following morning.^[63]

On the morning of 20 November, HMNZS Canterbury arrived at Lyttelton with another group of evacuees, bringing the total number evacuated from Kaikoura to more than 900.^[31]

Aftershocks

• 
  Magnitude of Kaikoura earthquakes
• 
  Number of aftershocks within 200 km of Kaikoura

See also

• List of earthquakes in 2016
• List of earthquakes in New Zealand
• Marlborough Fault System
• Tsunamis affecting New Zealand

References

External links

• Measuring uplift along the Kaikoura coast – GNS Science