Six months after the 4 September 2010 Mw 7.1 Darfield (Canterbury) earthquake, a Mw 6.2 Christchurch (Lyttelton) aftershock struck Christchurch on the 22 February 2011. This earthquake was centred approximately 10km south-east of the Christchurch CBD at a shallow depth of 5km, resulting in intense seismic shaking within the Christchurch central business district (CBD). Unlike the 4 Sept earthquake when limited-to-moderate damage was observed in engineered reinforced concrete (RC) buildings [35], in the 22 February event a high number of RC Buildings in the Christchurch CBD (16.2 % out of 833) were severely damaged. There were 182 fatalities, 135 of which were the unfortunate consequences of the complete collapse of two mid-rise RC buildings. This paper describes immediate observations of damage to RC buildings in the 22 February 2011 Christchurch earthquake. Some preliminary lessons are highlighted and discussed in light of the observed performance of the RC building stock. Damage statistics and typical damage patterns are presented for various configurations and lateral resisting systems. Data was collated predominantly from first-hand post-earthquake reconnaissance observations by the authors, complemented with detailed assessment of the structural drawings of critical buildings and the observed behaviour. Overall, the 22 February 2011 Mw 6.2 Christchurch earthquake was a particularly severe test for both modern seismically-designed and existing non-ductile RC buildings. The sequence of earthquakes since the 4 Sept 2010, particularly the 22 Feb event has confirmed old lessons and brought to life new critical ones, highlighting some urgent action required to remedy structural deficiencies in both existing and “modern” buildings. Given the major social and economic impact of the earthquakes to a country with strong seismic engineering tradition, no doubt some aspects of the seismic design will be improved based on the lessons from Christchurch. The bar needs to and can be raised, starting with a strong endorsement of new damage-resisting, whilst cost-efficient, technologies as well as the strict enforcement, including financial incentives, of active policies for the seismic retrofit of existing buildings at a national scale.
Questions to Ministers
1. Dr RUSSEL NORMAN to the Minister of Finance: What is the cost impact for the Earthquake Commission following Friday's High Court decision, and what now is the total cost to the Crown of the Canterbury earthquakes?
2. PESETA SAM LOTU-IIGA to the Minister of Finance: What steps has the Government taken to build a more competitive, export-focused economy?
3. Hon PHIL GOFF to the Prime Minister: Does he stand by his statement that "New Zealand simply can't afford a future where 20 percent of our workforce does not have the skills necessary for modern jobs"?
4. TIM MACINDOE to the Minister of Health: What was the average annual increase in elective discharges from 2000/2001 to 2007/2008, and how does this compare to the average annual increase in elective discharges over the last three financial years?
5. Hon PHIL GOFF to the Prime Minister: Does he stand by his statement in relation to part-privatisation of State-owned assets that "there will be some wholesale investors from overseas who will want to buy a little bit of these shares"?
6. KEITH LOCKE to the Minister of Defence: Was he briefed as to the presence of United States personnel at the Provincial Reconstruction Team base in Bamiyan and their duties; if so, what are the duties of the United States personnel at Bamiyan?
7. Hon ANNETTE KING to the Prime Minister: Does he stand by all his answers to Oral Question No 1 on 16 August 2011?
8. NIKKI KAYE to the Minister of Transport: What progress has the Government made on improving Auckland's commuter rail network?
9. Hon DAVID CUNLIFFE to the Minister of Finance: If he expects at least 85 to 90 percent of the State-owned assets he intends to privatise would remain in New Zealand's ownership, including the Crown's holding, what percent of the shares he plans to sell would be bought by foreign buyers?
10. NICKY WAGNER to the Minister of Education: What recent announcements has she made regarding trades academies?
11. Hon DAVID PARKER to the Acting Minister of Energy and Resources: Does she stand by the Government's decision to require Meridian Energy to sell some of its hydro-electricity dams on the Waitaki River to Genesis Energy, and how have the proceeds of the sale been used?
12. JONATHAN YOUNG to the Minister of Corrections: What reports has she received about efforts to cut re-offending rates and rehabilitate offenders?
Questions to Members
1. CLARE CURRAN to the Chairperson of the Transport and Industrial Relations Committee: Has he requested any submissions of evidence about the petition to the Transport and Industrial Relations Committee signed by nearly 14,000 people calling on the Government to retain the Hillside and Woburn workshops?
