Christchurch New Zealand 2011 (GNS)

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Event ID
201102212351
Event name
Christchurch
Country
New Zealand
Region in the country
Canterbury (South Island)
World region
Oceania
Epicentral coordinates (long/lat)
POINT(172.68 -43.583)
WKT GIS format
GEMECD contributing partner
GNS
Event narrative

On Tuesday February 22, 2011, at 12.51 pm local time, an earthquake of moment magnitude (Mw) 6.1 and focal depth 5 km struck the Canterbury Region, in New Zealand’s South Island. The epicenter (43.583 S, 172.68 E) was around 10 km south-east of Christchurch City (367,700 inhabitants[1]), near the port of Lyttleton.

This event is considered to be part of the aftershock sequence of the September 4, 2010 Darfield earthquake involving oblique-thrust faulting at the easternmost limit of previous aftershocks.

The proximity of the rupture (about 14km of subsurface rupture, GNS Science), and the shallow focal depth combined with the fact that much of the damage in Christchurch remained unrepaired since the September 2010 earthquake and following aftershocks have made the February 22, 2011 earthquake surprisingly devastating and damaging for its magnitude.

The earthquake produced exceptionally high values of ground shaking up to 2.2 g (vertical component) with another two readings beyond 1 g, and maximum intensity of MM IX-X. Extensive slope failures (landslides and rock falls) and liquefaction occurred.

1 Population at June 2011. New Zealand Statistics http://www.stats.govt.nz/

Date of occurrence (UTC)
2011-02-21
date
Time of occurrence (UTC)
23:51:00
time
Date of occurrence (local)
2011-02-22
date
Time of occurrence (local)
12:51:00
time
Day of the week (local)
Tuesday
Magnitude
6.1
Magnitude units
Moment (Mw)
Focal depth
5
km
Seismological data: source
USGS
Seismological data: comment

ShakeMap Atlas

Overall impact

Hardest hit was the city of Christchurch, especially the Central Business District (CBD) and its southern and eastern suburbs. The city is built on former swamps with coarser gravel deposits more common in the western part, and finer-grained sediment, such as sand, silt and clay in the eastern part close to the coast, the latter having a shallow groundwater level (0-2m).

Liquefaction was much more extensive and severe than in September’s earthquake causing higher extent of damage to buildings and to the lifeline systems of the city (in particular water and wastewater pipes). Roads and bridges were also damaged as effect of ground settlement and lateral spreading.

In general, the most significant damage to lifelines and residential buildings was due to liquefaction. Liquefaction phenomena resulted in widespread ejection of silt and fine sand (some of which contaminated by raw sewage) that created a significant demand in resources and time. Despite damage to homes, there were few serious injuries in residential houses in liquefaction areas[2].

The Port Hills area, built on volcanic rocks, experienced extensive rockfalls and rock slope failures leading to tens of houses being impacted by falling rocks (four people were killed by falling rocks[2]).

91% of the city’s 190000 dwellings suffered damage due to the earthquake, 7860 (as of April 8, 2013) of these were marked for demolition[3] and another 9,000 (excluding the red zone) were made uninhabitable (CERA, 2012). Over 1200 commercial and public buildings (including 212 heritage buildings[4]) were also slated for full or partial demolition, of which 900 were in the CBD.

The earthquake killed 185 people[5]: 115 people died due to the collapse of the CBD building and 18 due to the collapse of the PGC building. In addition 36 people were killed (mostly due to falling masonry) in the city’s CBD and another 12 in the suburbs (incl. 5 due to rockfalls). The remaining 4 fatalities were subsequently associated to the earthquake by the Chief Coroner since their death was caused by injuries suffered during the earthquake. The Accident Compensation Corporation received 7133 quake-related injury claims[6].

The earthquake had a huge economic impact with the overall direct economic loss estimated at 15-16 billion USD by SwissRe and MunichRe, respectively (9.5-10% of New Zealand’s GDP in 2011). Most of these losses are insured losses that are expected to reach 12-13 billion USD (SwissRe, MunichRe respectively).

EQC’s insurance payouts as of November 3, 2013 reached 6.32 billion NZD (5.23 billion USD) incl. claims for the whole Canterbury earthquake sequence (from September 4, 2010) with 57.6% of 744,248 accepted claims having been closed. EQC’s current projection (Nov. 3, 2013) is that the total payouts will reach 12 bilion NZD (9.96 billion USD).

2 TeAra, Encyclopedia of NZ http://www.teara.govt.nz/en/historic-earthquakes/page-13.
3 CERA. Environment Canterbury Preliminary Draft Land Use Recovery Plan (2013), at 36.
4 http://cardmakerschc.wordpress.com/2011/12/14/
christchurchs-heritage-buildings-are-a-must-keep-by-rebecca-macfie-listener-1-11-2011/
5 http://www.police.govt.nz/major-events/previous-major-events/christchurc...
6 http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10717855

Overview data
Loss: Human Casualty
show
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People injured
7133
number
People injured: source
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10717855
People injured: comment

Based on ACC Press Releases on April 8, 2011 there were 7133 injury claims, but it is not clear if the lists contained double counting due to multiple injuries per person as the data were by type of injury. The ACC estimated that 6659 people were injured in the first 24h (Ardagh et al., 2012. The initial health-system response to the earthquake in Christchurch, New Zealand, in February, 2011. Lancet 2012; 379, pp. 2109–15. DOI:10.1016/S0140-6736(12)60313-4).


People seriously injured
164
number
People seriously injured: source
http://www.stuff.co.nz/national/christchurch-earthquake/4698487/Christchurch-quake-at-a-glance
People seriously injured: comment

164 admitted to hospitals in the first 24 hours. In later press reports this has been revised to 141.


People missing
0
number

People killed
185
number
People killed: source
http://www.police.govt.nz/major-events/previous-major-events/christchurch-earthquake/list-deceased
People killed: comment

115 people incl. 4 unidentified people died in the Canterbury Television (CTV) building; 18 people died in the Pyne Gould Corporation (PGC) building; 8 people died on a bus crushed by falling masonry in the CBD; 28 people died in other areas of the CBD; 12 people died in suburban locations. 4 fatalities were subsequently associated to the earthquake by the Chief Coroner since their death was caused by injuries suffered during the earthquake.


People dying post catastrophe
0
number

People missing due to ground shaking
0
number

People killed due to ground shaking
180
number
People killed due to ground shaking: comment

133 (74%) killed by the collapse of two mid-rise reinforced concrete office buildings.


People dying post catastrophe due to shaking
0
number

People missing due to tsunami
0
number
People killed due to tsunami
0
number
People missing due to fire following
0
number
People killed due to fire following
0
number
People missing due to slope failures
0
number
People killed due to slope failures
5
number
People killed due to slope failures: source
Dellow G. et al. 2011. Landslides Caused By The 22 February 2011 Christchurch Earthquake And Managment Of Landslide Risk In The Immediate Aftermath. Bull. NZ Soc. Earth. Eng., Vol. 44, No. 4, pp. 227-238.
People killed due to slope failures: comment

Rock cliffs behind houses collapsed in the Sumner and Redcliffs area, and boulders tumbled from the Port Hills summits, with five people killed by falling rocks (one of which during an aftershock).

Loss: Building damage
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Total number of buildings destroyed by shaking
9200
number
Total number of buildings destroyed by shaking: source
GEMECD estimate
Total number of buildings destroyed by shaking: comment

Severe damage or collapse of buildings was induced by ground shaking (in the CBD) and liquefaction (in the suburbs of Christchurch). During the mainshock in the CBD: 710 (24%) red-tag buildings, plus 50 (1.7%) at risk from adjacent buildings. In the aftermath of the June 13, 2011 aftershock another 29 red-tag buildings, as well as 18 more at risk from adjacent stuctures (total 807 buildings or 27.2%).

Eventually when all surveys were completed there were 1,199 buildings (1,042 & 157 to be completely or partially demolished) in the CERA list of critical buildings (incl. non-residential). The list refers to cumulative damage during the whole 2010-12 Canterbury earthquakes sequence, incl. the effects of liquefaction.

In addition 7,779 houses in the liquefaction affected areas will be demolished under the Voluntary Crown Offer scheme (a system allowing families to relocate in new areas, safe from liquefaction hazard). Some double-counting may occur between the CERA and the Voluntary Crown Offer lists. Furthermore commercial buildings, vacant buildimgs and uninsured land owners in the residential red zone are not included in these figures.

Total number of buildings destroyed by shaking: status
Approximate

Number of buildings damaged by shaking
146000
number
Number of buildings damaged by shaking: source
GEMECD estimate
Number of buildings damaged by shaking: comment

According to the EQC, approximately 141,000 building damage claims were accepted that were solely related to the February 22, 2011 earthquake. Claims refer to individual properties (not buildings).

Approximately 5,000 out of 13,000 commercial and industrial buildings were damaged (Platt, S., 2012, Reconstruction in New Zealand Post 2010-11 Christchurch Eearthquakes, ReBuilDD Field Trip February 2012).

Number of buildings damaged by shaking: status
Approximate

Number of dwellings destroyed by shaking
9000
number
Number of dwellings destroyed by shaking: source
GEMECD estimate
Number of dwellings destroyed by shaking: status
Approximate

Number of dwellings damaged by shaking
148000
number
Number of dwellings damaged by shaking: source
GEMECD estimate & CERA (Canterbury Earthquake Recovery Authority), 2013, Preliminary Draft Land Use Recovery Plan; EQC (Canterbury Earthquakes): http://www.eqc.govt.nz/canterbury. Visited on March 10, 2012.
Number of dwellings damaged by shaking: comment

Of around 190,000 dwellings in Greater Christcurch about 91% were damaged (incl. those that were destroyed), about 110,000 Christchurch dwellings requiring major repairs, another 60,000 dwellings requiring smaller repairs (http://beckerfraserphotos.co.nz/post/46307415988/why-is-it-taking-so-lon...).

According to the EQC as of March 10, 2012, 156,590 building damage claims were accepted that were solely related to the February 22, 2011 earthquake.

Number of dwellings damaged by shaking: status
Approximate

Loss: Socioeconomic
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People homeless
40000
number
People homeless: source
CATDAT, 2001
People homeless: comment

According to an analysis of cellphone calls made by Christchurch users, around 55,000 residents may have left the city in the week after the February 2011 earthquake (CERA, 2013).
About 10,000 households displaced (http://www.oceanpartners.co.nz/earthquakes/)


Direct economic loss
16000
million US$
Direct economic loss: source
Munich Re
Direct economic loss: comment

16 billion US$ overall economic loss incl. 13 billion in insured losses (Munich Re).


Indirect economic loss
2715
million US$
Indirect economic loss: source
Layton B. (2013): Impact of Natural Disasters on Production Networks and Urbanization in New Zealand, ERIA-DP-2013-13,Aug. 2013, 64 p.
Indirect economic loss: comment

Estimated indirect losses due to the entire 2010-2012 Canterbury earthquakes sequence mostly due to GDP loss in Canterbury and temporary relocation costs for homes and businesses.


Insured loss
13000
million US$
Insured loss: source
Munich Re
Insured loss: comment

By February 23, 2012 (one year anniversary) the EQC had paid 1.315 billion US$ in claims with 15.5% of the claims closed, while 36% had not yet received any payment. These losses refer only to claims (buildings, contents, land) related to the February 22, 2011 Christchurch earthquake.

Insured loss: status
Approximate

Demographics
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Total number of buildings
200000
number
Total number of buildings: source
Miscellaneous
Total number of buildings: comment

Estimate of the total number of buildings in the greater Christchurch area.

Approximately 13,000 commercial and industrial buildings (Platt, S., 2012, Reconstruction in New Zealand Post 2010-11 Christchurch Eearthquakes, ReBuilDD Field Trip February 2012).

Total number of buildings: status
Approximate