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December 2010 Christchurch earthquake

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Coordinates: 43°33′S 172°38′E / 43.55°S 172.63°E / -43.55; 172.63
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Boxing Day earthquake
December 2010 Christchurch earthquake is located in New Zealand
December 2010 Christchurch earthquake
UTC time2010-12-25 21:30:15
ISC event15882518
USGS-ANSSComCat
Local date26 December 2010 (2010-12-26)
Local time10:30am NZDT (UTC+13)
MagnitudeMw 4.7
mb 4.5
Depth4–5 km (2–3 mi)
Epicentre43°33′S 172°38′E / 43.55°S 172.63°E / -43.55; 172.63[1]
Areas affectedChristchurch, New Zealand
Max. intensityMMI VI (Strong)

On 26 December 2010 a Mw4.7 earthquake occurred directly under the city centre of Christchurch, New Zealand, at a depth of between 4 and 5 km (2.5 and 3.1 mi). It caused "significant damage" to Christchurch and was part of the earthquake sequence beginning with the September 2010 Darfield earthquake, and followed by the 2011 Christchurch earthquake. As the earthquake occurred on Boxing Day, it is locally referred to as the Boxing Day earthquake rather than the December 2010 Christchurch earthquake. Businesses running their Boxing Day promotions at the time lost revenue due to the earthquake, and responded by re-running Boxing Day sales on 12 February 2011.

The earthquake caused strong ground shaking in the city centre but there were no casualties. It caused some masonry to fall onto streets, windows to break and a few walls to collapse, with damage being worst in the pedestrian mall City Mall. Damage mostly occurred on buildings that had been affected by the Darfield earthquake and its earlier aftershocks. Cordons were placed around two blocks and multiple separate buildings, and were mostly gone within a day. By 14 January, the Earthquake Commission received 6,895 damage claims.

Background

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A magnitude 7.1 Mw earthquake, known as the Darfield earthquake, occurred on 4 September 2010, and had, at the time, the biggest ground shaking ever to be recorded in New Zealand, at 1.26 g (1.26 times the acceleration of gravity).[2][3] The Darfield quake occurred along the Greendale Fault, and had thousands of shallow aftershocks over the coming months. Most occurred along the fault's surface trace, but there was also a zone of aftershocks extending northwards from the middle of the fault trace, as well as beyond the western and eastern (towards Christchurch) sides. The Boxing Day aftershock occurred in the eastern cluster.[4]: 3  Most aftershocks were under magnitude 3 and did not cause significant damage,[5] however a few did, including a magnitude 5.0 quake on 19 October, a magnitude 4.7 quake on 14 November,[6][7][8] the Mw 4.7 Boxing Day quake and the Mw 6.2 22 February 2011 earthquake. The February earthquake caused 185 deaths[9] and tens of billion dollars in damage.[10]

Earthquake

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The earthquake occurred at 10:30 a.m. on Boxing Day, 26 December 2010, and had a moment magnitude (Mw ) of 4.7 and local magnitude (ML) of 4.9.[11][12]: ii  The hypocentre was located 4–5 km (2.5–3.1 mi) under the city,[11][4]: ii  with an epicentre near Barbadoes Street,[13]: 7  or 1.8 km (1.1 mi) northwest of Christ Church Cathedral.[4]: ii  It was Christchurch's largest earthquake by magnitude since mid-November,[14] and the 17th biggest since the sequence began in September.[15]

The maximum peak ground acceleration measured 0.4 g, at Christchurch Botanic Gardens.[16][17]: 34  By contrast, the Mw 7.1 Darfield earthquake had peak ground accelerations in the central city ranging up to 0.3 g.[17]: 33  The Boxing Day earthquake did not last as long as the Darfield event, and hence resulted in less damage.[16] The shallow depth of the earthquake resulted in strong ground shaking, but due to the low magnitude,[17]: 34  it was restricted to within central Christchurch.[18][19]: 18 

The Boxing Day earthquake was followed by an aftershock sequence in the same area, with 'two dozen' occurring in the first 36 hours,[16] and more than 30 occurring within three-to-four weeks.[4]: ii, 1, 4, 7, 8  They mostly occurred within a 1 km2 (0.39 sq mi) area, at depths of 3.5–7 km (2.2–4.3 mi), along a steeply dipping strike-slip fault striking east–northeast.[4]: ii  Activity on that fault was spread over a distance of about 2.5 km (1.6 mi).[4]: 7  Five aftershocks had magnitudes of at least ML 4.0, and 20 measured ML 3.0 or greater.[12]: 1 

Because the earthquake did not occur on the Greendale Fault that ruptured in the Darfield earthquake, the Boxing Day earthquake does not fit GNS Science's definition of an aftershock, which should occur on the same fault. As it is likely that the Boxing Day earthquake resulted from the stress changes following the Darfield earthquake, it can be 'loosely' considered as an aftershock.[17]: 39 

Damage and effects

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The Boxing Day earthquake caused "significant" damage to Christchurch.[4]: 4  Damage mostly occurred to buildings that had already been damaged in the Darfield earthquake and its aftershocks.[20] Of the 3,000 buildings inspected within a day of the earthquake (out of 5,000) in Four Avenues, 115 needed repairs.[16]

Immediately after the earthquake, 40,000 homes in Papanui, St Albans and Fendalton lost power. It took about an hour for it to be mostly restored, and the power network did not experience significant damage.[14] The earthquake also caused windows to break, including those in shop fronts.[21] A few walls collapsed[14] and a few buildings had masonry fall onto streets,[22] including the Southern Encounter Aquarium building in Cathedral Square.[23] Several buildings had a few cracks form and bricks loosened.[15][24] Some sprinkler pipes broke[24] and the upper section of a building fell onto Manchester Street.[21] The damage was worst in City Mall, a pedestrian mall, "where an internal wall collapsed and building parapets crumbled", and some doors jammed which trapped people in buildings.[14] Bricks and debris fell off a building and crashed through the roof of a restaurant in City Mall, crushing several tables. According to the owner, if the restaurant was operating at the time of the earthquake, people could have died as a result.[25] There was no damage to water, wastewater or stormwater networks[26] and no reports of injuries.[27]

By 6 January, the Earthquake Commission had received 3,500 damage compensation claims,[28] and that rose to 6,895 by 14 January.[29] By contrast, the Darfield earthquake had 157,000 at that point in time,[30] the 19 October earthquake had 2,139 claims on 6 January and the 14 November aftershock had 1,986.[28] This was also more than the 6,200 claims received after the Mw 6.7 2007 Gisborne earthquake.[29][31]

An expert panel report commissioned by the Department of Building and Housing concluded that the Boxing Day and Darfield quakes "did not significantly reduce the earthquake resistance" of four major buildings that experienced building failure in the February 2011 earthquake: the CTV Building, the PGC Building, the Hotel Grand Chancellor building and the Forsyth Barr Building.[19]: 87 

Response

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Shortly after the earthquake, hundreds of shoppers were evacuated from the Westfield Riccarton shopping mall.[20] The fire service received 200 emergency calls, mostly from alarm activations. Other calls included gas leaks, small fires,[14] and people being trapped in lifts or stairwells.[23] Due to concerns about unstable structures, cordons were placed around two blocks and multiple separate buildings,[14] including in City Mall[16] and a section of Poplar Lane.[32] In the late afternoon, these restricted zones were slowly scaled back,[14] and mostly gone by the morning of 27 December.[33] Police made three arrests relating to the cordons.[27] A Civil Defence Emergency Operations Centre was set up at the city council's Hereford Street building.[20]

The earthquake occurred on Boxing Day, which is one of the biggest shopping events of the year,[14] giving it the name "Boxing Day" earthquake.[12]: ii  The quake caused a few shops to close,[24] and retailers experienced a drop in revenue: Christchurch electronic transactions were down 10.7% from the previous year, which was more than the national drop of 6.7%.[34] To recoup for these losses, Boxing Day sales were re-run on 12 February 2011.[35] It was launched by Mayor Bob Parker and Earthquake Recovery Minister Gerry Brownlee at City Mall,[36] and received funding from the government, the city council and earthquake trusts.[37]

Despite claims that New Year's Eve celebrations at Cathedral Square had to be relocated due to the damage, it did not happen.[38][39] After structural assessments determined that there was no public danger, the council decided that the celebrations would continue and expected 15,000 attendees.[38]

See also

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References

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  1. ^ "Major Christchurch Events before February 22" (PDF). Canterbury Earthquakes Royal Commission. Department of Internal Affairs. July 2012. Archived (PDF) from the original on 10 June 2024. Retrieved 10 June 2024.
  2. ^ "2010 Darfield (Canterbury) Earthquake". GNS Science. 2011. Archived from the original on 28 July 2012. Retrieved 27 August 2011.
  3. ^ Segou, Margaret; Kalkan, Erol (2011). "Ground Motion Attenuation during M 7.1 Darfield and M 6.2 Christchurch, New Zealand, Earthquakes and Performance of Global Predictive Models" (PDF). Seismological Research Letters. 82 (6). doi:10.1785/gssrl.82.6.866.
  4. ^ a b c d e f g Bannister, Stephen (March 2011). "Relocation Analysis of the Christchurch City "Boxing Day" Earthquakes GNS Science Consultancy Report 2011/36" (PDF). Earthquake Commission. Archived (PDF) from the original on 5 September 2024. Retrieved 15 August 2024.
  5. ^ "2010 Canterbury (Darfield) earthquake". New Zealand History. Ministry for Culture and Heritage. Retrieved 1 March 2025.
  6. ^ "Canterbury Earthquake EQC Claims Info". The Press. Stuff. 15 January 2011. Retrieved 1 March 2025.
  7. ^ "Major Christchurch Events before February 22" (PDF). Canterbury Earthquakes Royal Commission. July 2012. Archived from the original (PDF) on 23 April 2017. Retrieved 1 March 2025.
  8. ^ "No reports of damage following Canterbury aftershock". New Zealand Press Association. Otago Daily Times. 14 November 2014. Retrieved 10 September 2024.
  9. ^ "The 2011 Christchurch earthquake". Te Ara: The Encyclopedia of New Zealand. Archived from the original on 2 December 2023. Retrieved 18 August 2024.
  10. ^ "Canterbury Earthquakes". Insurance Council of New Zealand. Retrieved 27 February 2025.
  11. ^ a b "Magnitude 4.7, Sun Dec 26 2010 10:30 AM". GeoNet. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  12. ^ a b c Ristau, John (February 2011). "Focal mechanism analysis of Christchurch Boxing Day aftershocks" (PDF). Earthquake Commission. pp. ii, 1–6. Archived (PDF) from the original on 9 August 2024. Retrieved 9 August 2024.
  13. ^ Yuen Kam, Weng; Pampanin, Stefano (November 2011). "General Building Performance in the Christchurch CBD: a contextual report" (PDF). Ministry of Business, Innovation and Employment. Retrieved 2 March 2025.
  14. ^ a b c d e f g h Davison, Isaac (27 December 2010). "'Explosive' aftershocks hit weary city". The New Zealand Herald. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  15. ^ a b Gorman, Paul; Brown, Giles (27 December 2010). "Quake directly beneath Christchurch". The Press. Stuff. Archived from the original on 23 April 2024. Retrieved 9 August 2024.
  16. ^ a b c d e "Shaking more violent than September 4 quake". New Zealand Press Association. Otago Daily Times. 28 December 2010. Archived from the original on 10 August 2024. Retrieved 10 August 2024.
  17. ^ a b c d Final Report – Part One. Canterbury Earthquakes Royal Commission (Report). Vol. 1. 2012. 2.7.1.2 The Boxing Day earthquake. Retrieved 28 February 2025.
  18. ^ Gorman, Paul (26 December 2010). "The science behind the shakes". Fairfax New Zealand. Archived from the original on 26 October 2012. Retrieved 11 September 2011.
  19. ^ a b "Structural Performance of Christchurch CBD Buildings in the 22 February 2011 Aftershock" (PDF). Ministry of Business, Innovation and Employment. February 2012. Archived (PDF) from the original on 19 February 2023. Retrieved 15 August 2024.
  20. ^ a b c "'Significant number' of buildings damaged in aftershocks". New Zealand Press Association. 26 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  21. ^ a b "Boxing Day aftershock". The New Zealand Herald. 26 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  22. ^ "New Zealand's Christchurch hit by strong aftershocks". BBC News. 26 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  23. ^ a b "Violent aftershocks hit Christchurch". Stuff. New Zealand. 26 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  24. ^ a b c Dickison, Michael (28 December 2010). "Major aftershock cruel blow for struggling stores". The New Zealand Herald. Archived from the original on 5 September 2024. Retrieved 9 August 2024.
  25. ^ Carville, Olivia (29 December 2010). "Another miracle of Christchurch quake timing". The Press. Stuff. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  26. ^ "150 claims after swarm of quakes". New Zealand Press Association. 27 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  27. ^ a b "Christchurch aftershocks 'serious setback'". New Zealand Press Association and The Press. Stuff. 27 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  28. ^ a b "Almost 3500 claims from Boxing Day quake". New Zealand Press Association. 6 January 2011. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  29. ^ a b "Boxing Day Christchurch quake claims near 7000". The New Zealand Herald. 14 January 2011. Archived from the original on 15 June 2024. Retrieved 9 June 2024.
  30. ^ "Canterbury Earthquake EQC Claims Info". The Press. Stuff. 15 January 2011. Archived from the original on 16 August 2024. Retrieved 16 August 2024.
  31. ^ "M 6.7 Gisborne Thu, Dec 20 2007". GeoNet. Retrieved 27 February 2025.
  32. ^ "Council identifies quake repairs, DHB gives advice". New Zealand Press Association. The New Zealand Herald. 27 December 2010. Archived from the original on 5 September 2024. Retrieved 9 August 2024.
  33. ^ "Christchurch reopens after quakes". New Zealand Press Association. The New Zealand Herald. 27 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  34. ^ Sachdeva, Sam (28 December 2010). "Christchurch shops vow to bounce back". The Press. Stuff. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  35. ^ "City retailers say full sale ahead". The Press. 11 February 2011. Archived from the original on 16 August 2024. Retrieved 17 August 2024.
  36. ^ "Christchurch has another go at Boxing Day sales". RNZ. 12 February 2011. Archived from the original on 10 August 2024. Retrieved 10 August 2024.
  37. ^ Smith, Cullen (11 February 2011). "Central city set for 'Boxing Day' sale". The Star. Archived from the original on 17 August 2024. Retrieved 17 August 2024.
  38. ^ a b "Cathedral Square NYE party to go ahead". The New Zealand Herald. 30 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
  39. ^ "Christchurch may need new NYE party venue". Newstalk ZB. The New Zealand Herald. 28 December 2010. Archived from the original on 9 August 2024. Retrieved 9 August 2024.
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