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June 2011 Christchurch earthquake: Difference between revisions

Coordinates: 43°25′52″S 172°42′36″E / 43.431°S 172.710°E / -43.431; 172.710
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Subsequent severe shaking in the city registered at VIII on the [[Mercalli intensity scale|Mercalli scale]],<ref name=geonet2/> destroying some buildings and causing additional damage to many structures affected by previous earthquakes. The damaged tower of the historic [[Lyttelton Timeball Station]] collapsed before dismantlement work could be completed. The earthquake also downed phone lines and triggered widespread power outages, leaving around 54,000 households without power. Rebuilding costs were estimated to increase by NZ$6 billion (US$ 4.83 billion) due to additional damage from the quake.<ref>{{cite web|url=http://tvnz.co.nz/national-news/christchurch-quake-bill-could-rise-6-billion-4227216|title=Christchurch quake bill could rise 6 billion|date=16 June 2011|author=[[One News (New Zealand)|ONE News]]|publisher=[[World TV Limited|Television New Zealand Limited]]}}</ref>
Subsequent severe shaking in the city registered at VIII on the [[Mercalli intensity scale|Mercalli scale]],<ref name=geonet2/> destroying some buildings and causing additional damage to many structures affected by previous earthquakes. The damaged tower of the historic [[Lyttelton Timeball Station]] collapsed before dismantlement work could be completed. The earthquake also downed phone lines and triggered widespread power outages, leaving around 54,000 households without power. Rebuilding costs were estimated to increase by NZ$6 billion (US$ 4.83 billion) due to additional damage from the quake.<ref>{{cite web|url=http://tvnz.co.nz/national-news/christchurch-quake-bill-could-rise-6-billion-4227216|title=Christchurch quake bill could rise 6 billion|date=16 June 2011|author=[[One News (New Zealand)|ONE News]]|publisher=[[World TV Limited|Television New Zealand Limited]]}}</ref>

The earthquake was felt across the South Island and southern North Island, including Wellington and Nelson.


Immediate reports following the quake indicated that at least 10 people were injured and hospitalised; however, the number rose to a total of 46 injuries the next day.<ref name=injuryupdate /><ref name=injured>{{cite web|url=http://www.reuters.com/article/2011/06/13/us-newzealand-quake-idUSTRE75C08S20110613|title=Powerful quakes rattle New Zealand city|date=13 June 2011|accessdate=13 June 2011|last=Bathgate|first=Adrian|publisher=[[Reuters]]}}</ref> One elderly rest home resident lost consciousness when he fell during the quake and died later that night, although police say his death may not have been caused by the earthquake.<ref name="Death from quake?">{{cite web |url=http://www.nzherald.co.nz/christchurch-earthquake/news/article.cfm?c_id=1502981&objectid=10732204 |title=Elderly man may not be quake casualty |work=[[The New Zealand Herald]] |author=NZPA |date=14 June 2011 |accessdate=14 June 2011}}</ref><ref name=death>{{cite web|url=http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10732161|title=One death reported after earthquake|work=[[The New Zealand Herald]]|author=Herald Online, NZPA|date=14 June 2011|accessdate=14 June 2011}}</ref>
Immediate reports following the quake indicated that at least 10 people were injured and hospitalised; however, the number rose to a total of 46 injuries the next day.<ref name=injuryupdate /><ref name=injured>{{cite web|url=http://www.reuters.com/article/2011/06/13/us-newzealand-quake-idUSTRE75C08S20110613|title=Powerful quakes rattle New Zealand city|date=13 June 2011|accessdate=13 June 2011|last=Bathgate|first=Adrian|publisher=[[Reuters]]}}</ref> One elderly rest home resident lost consciousness when he fell during the quake and died later that night, although police say his death may not have been caused by the earthquake.<ref name="Death from quake?">{{cite web |url=http://www.nzherald.co.nz/christchurch-earthquake/news/article.cfm?c_id=1502981&objectid=10732204 |title=Elderly man may not be quake casualty |work=[[The New Zealand Herald]] |author=NZPA |date=14 June 2011 |accessdate=14 June 2011}}</ref><ref name=death>{{cite web|url=http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10732161|title=One death reported after earthquake|work=[[The New Zealand Herald]]|author=Herald Online, NZPA|date=14 June 2011|accessdate=14 June 2011}}</ref>

Revision as of 03:42, 18 June 2011

June 2011 Christchurch earthquake
Map showing the epicentre of the earthquake
Lua error in Module:Location_map at line 392: The value "−43.431" provided for latitude is not valid.
UTC time??
Magnitude6.3 ML[1]
Depth6.0 km (4 mi)
Epicenter43°25′52″S 172°42′36″E / 43.431°S 172.710°E / -43.431; 172.710
TypeAftershock
Areas affected New Zealand
Total damageBuilding collapse, power outages, broken water pipes, soil liquefaction, rockfall
Max. intensityMM VIII[2][3]
Peak acceleration0.78g (city); 2.13g (epicentre)[4]
TsunamiNo
Casualties1 dead (perhaps not from quake),[5] 46 injured (2 critically)[6]

The June 2011 Christchurch earthquake was a shallow magnitude 6.3 ML earthquake that occurred on Monday, 13 June 2011 at 02:20 UTC. It was centred at a depth of 6.0 km (4 mi), about 13 km (8 mi) from Christchurch, which had previously been devastated by a magnitude 6.3 ML aftershock of the major 2010 Canterbury earthquake.[1] The quake was preceded by a magnitude 5.6 ML tremor that struck the region at a slightly deeper 10 km (6.2 mi).[7] It was separately reported by the USGS as a magnitude 6.0 Mw event, focused at about 9 km (5.6 mi) below the surface.[8]

Subsequent severe shaking in the city registered at VIII on the Mercalli scale,[3] destroying some buildings and causing additional damage to many structures affected by previous earthquakes. The damaged tower of the historic Lyttelton Timeball Station collapsed before dismantlement work could be completed. The earthquake also downed phone lines and triggered widespread power outages, leaving around 54,000 households without power. Rebuilding costs were estimated to increase by NZ$6 billion (US$ 4.83 billion) due to additional damage from the quake.[9]

The earthquake was felt across the South Island and southern North Island, including Wellington and Nelson.

Immediate reports following the quake indicated that at least 10 people were injured and hospitalised; however, the number rose to a total of 46 injuries the next day.[6][10] One elderly rest home resident lost consciousness when he fell during the quake and died later that night, although police say his death may not have been caused by the earthquake.[5][11]

Background

New Zealand in its entirety, particularly the North Island, is located along the seismically volatile Pacific Ring of Fire, and has a long history of earthquakes. Since the European settlement, the largest on record was a magnitude 8.2 ML major earthquake that occurred on January 23, 1855 near the Wairarapa plains of the North Island. Another destructive magnitude 7.8 ML earthquake struck the region near Hawke's Bay on February 3, 1931; to date, it is the deadliest earthquake recorded on the island, greatly affecting much of Napier and Hastings.[12]

In comparison, the South Island has experienced fewer large earthquakes. The magnitude 7.1 Mw event of 4 September 2010 was by far the strongest earthquake recorded in the Canterbury Region of the island, triggering a large number of aftershocks. Although similar aftershock sequences have historically occurred around world, such occurrences were geologically extremely unusual in the region, which had shown low levels of seismic activity for thousands of years. As a result, the event has led to the discovery of new geological faults across central-eastern South Island, particularly under regional plains and the adjacent seabed.[13]

Geology

USGS shake map

The magnitude 6.3 ML earthquake occurred inland on 13 June 2011 at 02:20 UTC at a shallow depth of 6.0 km (4 mi), about 13 km (8 mi) to the north-northeast of Christchurch, New Zealand.[1] Owing to the interaction of the major Pacific and Australia Plates, regional plate boundary deformation is observed in much of central South Island. The earthquake was a direct result of strike-slip faulting at the eastern end of the rupture of another strong magnitude 6.3 ML earthquake, which occurred on 22 February 2011 along the Port Hills Fault.[14] It was preceded by a moderate magnitude 5.6 ML tremor with a similar focal mechanism that struck one hour and 20 minutes earlier.[15] Experts believe the quakes were triggered by a previously undiscovered fault in the region, located several kilometres south of the Port Hills Fault.[16] The US Geological Survey reported a magnitude of 6.0 Mw and a focal depth of 9 km (5.6 mi) for the earthquake, while the precursor tremor was assigned a magnitude of 5.2 Mw at a similar depth.[7][8]

Seismologists reported that the earthquakes were part of a prolonged aftershock sequence associated with the major magnitude 7.1 earthquake of September 2010, which includes the February 2011 event.[14] They were succeeded by multiple lighter aftershocks; the strongest, a moderate magnitude 5.0 ML tremor, struck the region two days later.[17] Despite significant energy release, the earthquakes were believed to have increased the risk of an additional aftershock of similar magnitude; calculations from GNS Science indicated a 23 percent probability of a magnitude 6.0–6.9 ML earthquake occurring in the Canterbury aftershock zone within the 12 months following the event.[16]

Focused only several kilometres below the surface, the earthquake resulted in significant shaking over a large portion of central-eastern South Island. Maximum ground motions registered at VIII (severe) on the Mercalli intensity scale in Christchurch, while strong shaking (MM VI) was felt in adjacent populated areas such as Rolleston and Lincoln. The landforms of Sumner recorded intensified shaking through seismic wave lensing due to the effects of its topographic setting.[18] Widespread lighter motions were observed throughout much of the remaining region,[19] with slight damage to property reported from as far afield as Dunedin. The earthquake was felt as far away as New Plymouth and Invercargill.[3]

Damage, casualties and effects

Soil liquefaction caused by the earthquake

The earthquake and its precursor tremor struck during the afternoon near an extremely populated area, with most buildings in the area damaged by previous earthquakes. Around 400,000 people were directly affected and were estimated to have experienced at least strong (MM VI) shaking.[19] Hospital officials confirmed at least 46 injuries; several people were hit by falling debris, while two others were reported to be in critical condition.[6] In the city centre, two workers were rescued and hospitalised following the collapse of a church. The following morning, an elderly man was confirmed dead after being knocked down and becoming unconscious in a rest home during the earthquake.[11]

Phone lines were out and power was lost to about 54,000 households in the wake of the earthquake. Flooding was reported across several streets due to broken water mains.[20] Shopping malls and office buildings were evacuated, and at least one church was reported to have collapsed. Furthermore, officials ordered the closure of bridges in the area as a precautionary measure;[21] one bridge was reported to have succumbed to the strong ground motions.[20] Days after the earthquake, a small electrical fire ignited in a control panel at Christchurch Hospital due to dislodged wiring as a result of ongoing aftershocks.[22]

Strong ground motions caused many secondary effects, including gas leaks and widespread soil liquefaction.[20] Consequently, sand boils were observed on asphalt roads, toppling few cars and sinking another.[23] Several houses in the hill suburbs of Sumner and Redcliffs were affected by falling boulders from hillsides.[10] Following its occurrence, water pressure was lost across much of Christchurch; residents were urged to conserve water use.[24] In some parts of the Heathcote Valley, previously dormant or non-existent natural springs emerged as a consequence of the sudden rise in the water table, flooding some properties.[25]

The NZX 50 Index fell by 0.4 percent to its lowest level since April 20; within the index, a total of 24 stocks fell, while six rose and 20 remained unchanged.[26] In addition, the New Zealand dollar declined in the wake of the disaster, reportedly dropping by nearly 0.01 US dollar, or about 1.3 percent.[27]

Damage evaluation

Though the exact extent of losses remains unclear, the earthquake caused further damage to many structures in Christchurch; approximately half of the buildings in the centre of the city were already damaged or destroyed by previous strong earthquakes.[28] Preliminary assessments indicate an additional 50 buildings were rendered beyond repair in the area.[29] Despite its moderate magnitude, the preceding magnitude 5.7 tremor caused several two-story buildings at a road intersection in the city to collapse.[30]

In spite of earlier renovation attempts, authorities were considering the complete demolition of the 130-year-old Christchurch cathedral. The building was reported to be structurally compromised due to the collapse of its western wall, while strong shaking shattered its stained glass rose window.[31] The tower of the historic Lyttelton Timeball Station, which sustained damage from the February 2011 earthquake, collapsed after plans to dismantle the building had been initiated.[32] Lyttelton Port, a major harbour in the region, suffered additional damage from the tremors and was to perform full engineering assessments.[33] Multiple hospitals and residential care facilities in Christchurch were without essential services, and some reported considerable damage to infrastructure.[34]

Response

Months before the event, a stronger magnitude 6.3 earthquake occurred in a similar area near Christchurch, causing widespread destruction and fatalities. Concerns arose about the condition of previously damaged structures, and the earthquakes caused further distress among many victims.[20] Dozens of dissatisfied residents were expected to permanently relocate and leave the city, and many others sought professional help for anxiety and depression-related issues.[35][36] Essential organisations in the area were evacuated as a safety precaution, including the police headquarters and offices of the Canterbury Earthquake Recovery Authority.[37] Flight operations were halted at Christchurch International Airport, but resumed later in the day.[24] The Student Volunteer Army — which partook in silt shifting after the February 2011 quake — prepared to again launch street clearing actions.[38]

Relief efforts

In the immediate aftermath of the earthquakes, the National Crisis Management Centre was activated through The Ministry of Civil Defence and Emergency Management in order to manage public response to the disaster,[37] and hundreds of police officers were dispatched to patrol the city streets. Authorities were prompted to set up an outdoors emergency operations centre, as well as a public welfare centre to provide shelter to victims overnight.[24] A total of NZ$285,000 was allocated for donations to nine charities, including NZ$40,000 to both the Red Cross Christchurch earthquake appeal and the Canterbury Earthquake Appeal Salvation Army funds.[38] At Westpac Bank, a public donation account was opened to raise money in order to provide financial assistance for earthquake victims.[39]

See also

References

  1. ^ a b c "New Zealand Earthquake Report - Jun 13 2011 at 2:20 pm (NZST)". GeoNet. GNS Science. Retrieved 14 June 2011.
  2. ^ USGS (13 June 2011). "Pager Version 2 - M 6.0, South Island of New Zealand" (PDF). Retrieved 13 June 2011.
  3. ^ a b c "New Zealand Earthquake Report - Jun 13 2011 at 2:20 pm (NZST)". GeoNet. GNS Science.
  4. ^ "Large earthquakes strike south-east of Christchurch". GeoNet. 14 June 2011. Retrieved 14 June 2011.
  5. ^ a b NZPA (14 June 2011). "Elderly man may not be quake casualty". The New Zealand Herald. Retrieved 14 June 2011.
  6. ^ a b c The Press (14 June 2011). "Shattered city hit again". Fairfax New Zealand Limited. Retrieved 13 June 2011.
  7. ^ a b "New Zealand Earthquake Report - Jun 13 2011 at 1:00 pm (NZST)". GeoNet. GNS Science. 13 June 2011. Retrieved 14 June 2011. Cite error: The named reference "foreshock" was defined multiple times with different content (see the help page).
  8. ^ a b "Magnitute 6.0 - South Island of New Zealand". USGS. 13 June 2011. Retrieved 13 June 2011.
  9. ^ ONE News (16 June 2011). "Christchurch quake bill could rise 6 billion". Television New Zealand Limited.
  10. ^ a b Bathgate, Adrian (13 June 2011). "Powerful quakes rattle New Zealand city". Reuters. Retrieved 13 June 2011.
  11. ^ a b Herald Online, NZPA (14 June 2011). "One death reported after earthquake". The New Zealand Herald. Retrieved 14 June 2011.
  12. ^ Chapman, Paul (22 February 2011). "Christchurch earthquake: history of New Zealand tremors". The Telegraph. Retrieved 15 June 2011.
  13. ^ "Editorial: Christchurch people need to hear the truth". The New Zealand Herald. 16 June 2011.
  14. ^ a b "Earthquake Summary for the June 13, 2011 South Island, New Zealand earthquake". USGS. 13 June 2011. Retrieved 13 June 2011.
  15. ^ "New Zealand Earthquake Report - Jun 13 2011 at 1:00 pm (NZST)". GeoNet. 13 June 2011. Retrieved 14 June 2011.
  16. ^ a b The Press (14 June 2011). "Monday's quakes reveal new fault". Fairfax New Zealand Limited. Retrieved 14 June 2011.
  17. ^ "New Zealand Earthquake Report - Jun 15 2011 at 6:27 am (NZST)". GeoNet. GNS Science. 15 June 2011.
  18. ^ Jones, Nicholas/Harper, Paul (15 June 2011). "Big aftershock more likely - GNS". The New Zealand Herald. Retrieved 16 June 2011.{{cite web}}: CS1 maint: multiple names: authors list (link)
  19. ^ a b USGS (13 June 2011). "Pager - M 6.0 - South Island of New Zealand". Retrieved 13 June 2011.
  20. ^ a b c d NZ Staff wire (13 June 2011). "Second major 6.0 aftershock hits Christchurch". The New Zealand Herald. Retrieved 13 June 2011.
  21. ^ CNN Wire Staff (13 June 2011). "Dual quakes rock Christchurch, New Zealand". CNN. Retrieved 13 June 2011. {{cite web}}: |author= has generic name (help)
  22. ^ Voxy Newswire (17 June 2011). "Christchurch DHB earthquake update". Voxy.co.nz. Retrieved 17 June 2011.
  23. ^ Lilley, Ray (13 June 2011). "Strong quakes again rock shaken New Zealand city". Associated Press. Retrieved 13 June 2011.
  24. ^ a b c NZ Staff wire (13 June 2011). "Christchurch hit by swarm of earthquakes". The New Zealand Herald. Retrieved 13 June 2011.
  25. ^ RNZ (16 June 2011). "Springs created by quake cause flooding". Radio New Zealand. Retrieved 17 June 2011. {{cite web}}: Cite has empty unknown parameter: |1= (help)
  26. ^ BusinessDesk (13 June 2011). "NZ stocks fall on quake". Fairfax New Zealand Limited. Retrieved 13 June 2011. {{cite web}}: |author= has generic name (help)
  27. ^ NBR staff (13 June 2011). "NZ dollar plunges after earthquakes". National Business Review. Retrieved 13 June 2011.
  28. ^ "Powerful earthquakes have again rocked Canterbury on Monday, causing injury and damage". Radio New Zealand. 13 June 2011. Retrieved 13 June 2011.
  29. ^ The Press (14 June 2011). "More Christchurch homes beyond repair". Fairfax New Zealand Limited. Retrieved 14 June 2011.
  30. ^ Wade, Amelia/Booker, Jarrod/Chatterton, Tracey/King, Caroline (14 June 2011). "Terror returns as earthquakes rock city". The New Zealand Herald. Retrieved 14 June 2011.{{cite web}}: CS1 maint: multiple names: authors list (link)
  31. ^ Agence France-Presse (16 June 2011). "Quake-hit cathedral facing demolition". Google Hosted News. Retrieved 16 June 2011.
  32. ^ "Timeball Station collapses in quake". The New Zealand Herald. 13 June 2011. Retrieved 13 June 2011.
  33. ^ Lyttelton Port Company (13 June 2011). "Media Release from Lyttelton Port of Christchurch". Scoop Media. Retrieved 13 June 2011.
  34. ^ NZ Online (13 June 201). "Health concerns highlights after latest quake". New Zealand Herald. Retrieved 13 June 2011.
  35. ^ McLean, Tamara/AAP (13 June 2011). "Christchurch warned: more quakes to come". The Sydney Morning Herald. Retrieved 13 June 2011.
  36. ^ The Press (17 June 2011). "Mental health takes big hit from quakes". Fairfax New Zealand Limited. Retrieved 17 June 2011.
  37. ^ a b NZ Herald staff (13 June 2011). "Latest updates: 'This place is going mad'". The New Zealand Herald. Retrieved 13 June 2011.}
  38. ^ a b Staff writer (14 June 2011). "Chch quake upgraded now equal to February". 3News. Retrieved 14 June 2011.
  39. ^ "Donate a dollar for Christchurch". The Southland Times. Fairfax New Zealand Limited. 15 June 2011. Retrieved 16 June 2011.
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