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Research papers, University of Canterbury Library

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.

Research papers, University of Canterbury Library

In 2010 and 2011 Christchurch, New Zealand experienced a series of earthquakes that caused extensive damage across the city, but primarily to the Central Business District (CBD) and eastern suburbs. A major feature of the observed damage was extensive and severe soil liquefaction and associated ground damage, affecting buildings and infrastructure. The behaviour of soil during earthquake loading is a complex phenomena that can be most comprehensively analysed through advanced numerical simulations to aid engineers in the design of important buildings and critical facilities. These numerical simulations are highly dependent on the capabilities of the constitutive soil model to replicate the salient features of sand behaviour during cyclic loading, including liquefaction and cyclic mobility, such as the Stress-Density model. For robust analyses advanced soil models require extensive testing to derive engineering parameters under varying loading conditions for calibration. Prior to this research project little testing on Christchurch sands had been completed, and none from natural samples containing important features such as fabric and structure of the sand that may be influenced by the unique stress-history of the deposit. This research programme is focussed on the characterisation of Christchurch sands, as typically found in the CBD, to facilitate advanced soil modelling in both res earch and engineering practice - to simulate earthquake loading on proposed foundation design solutions including expensive ground improvement treatments. This has involved the use of a new Gel Push (GP) sampler to obtain undisturbed samples from below the ground-water table. Due to the variable nature of fluvial deposition, samples with a wide range of soil gradations, and accordingly soil index properties, were obtained from the sampling sites. The quality of the samples is comprehensively examined using available data from the ground investigation and laboratory testing. A meta-quality assessment was considered whereby a each method of evaluation contributed to the final quality index assigned to the specimen. The sampling sites were characterised with available geotechnical field-based test data, primarily the Cone Penetrometer Test (CPT), supported by borehole sampling and shear-wave velocity testing. This characterisation provides a geo- logical context to the sampling sites and samples obtained for element testing. It also facilitated the evaluation of sample quality. The sampling sites were evaluated for liquefaction hazard using the industry standard empirical procedures, and showed good correlation to observations made following the 22 February 2011 earthquake. However, the empirical method over-predicted liquefaction occurrence during the preceding 4 September 2010 event, and under-predicted for the subsequent 13 June 2011 event. The reasons for these discrepancies are discussed. The response of the GP samples to monotonic and cyclic loading was measured in the laboratory through triaxial testing at the University of Canterbury geomechanics laboratory. The undisturbed samples were compared to reconstituted specimens formed in the lab in an attempt to quantify the effect of fabric and structure in the Christchurch sands. Further testing of moist tamped re- constituted specimens (MT) was conducted to define important state parameters and state-dependent properties including the Critical State Line (CSL), and the stress-strain curve for varying state index. To account for the wide-ranging soil gradations, selected representative specimens were used to define four distinct CSL. The input parameters for the Stress-Density Model (S-D) were derived from a suite of tests performed on each representative soil, and with reference to available GP sample data. The results of testing were scrutinised by comparing the data against expected trends. The influence of fabric and structure of the GP samples was observed to result in similar cyclic strength curves at 5 % Double Amplitude (DA) strain criteria, however on close inspection of the test data, clear differences emerged. The natural samples exhibited higher compressibility during initial loading cycles, but thereafter typically exhibited steady growth of plastic strain and excess pore water pressure towards and beyond the strain criteria and initial liquefaction, and no flow was observed. By contrast the reconstituted specimens exhibited a stiffer response during initial loading cycles, but exponential growth in strains and associated excess pore water pressure beyond phase-transformation, and particularly after initial liquefaction where large strains were mobilised in subsequent cycles. These behavioural differences were not well characterised by the cyclic strength curve at 5 % DA strain level, which showed a similar strength for both GP samples and MT specimens. A preliminary calibration of the S-D model for a range of soil gradations is derived from the suite of laboratory test data. Issues encountered include the influence of natural structure on the peak-strength–state index relationship, resulting in much higher peak strengths than typically observed for sands in the literature. For the S-D model this resulted in excessive stiffness to be modelled during cyclic mobility, when the state index becomes large momentarily, causing strain development to halt. This behaviour prevented modelling the observed re- sponse of silty sands to large strains, synonymous with “liquefaction”. Efforts to reduce this effect within the current formulation are proposed as well as future research to address this issue.

Images, Alexander Turnbull Library

The cartoon's title is 'Life in the South Island'. A man wonders aloud to his wife when the 'plague of locusts' will arrive as they have had 'collapsing finance companies, earthquakes' and 'heavy snow damage'. Refers to the collapse of South Canterbury Finance, the earthquake of 4th September, and more recently, heavy snow in Southland that has caused roofs to collapse. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

Text reads 'Water - One minute too much - The next, not enough' In the first frame a man is fed up with another downpour and in the second frame there is shown a plastic bottle of drinking water. Refers to the amount of rain in recent times but also the need for bottled or boiled water In Canterbury after the earthquake of 4th September 2010 which caused major damage to sewage and water systems. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

Text reads '150 great reasons to live in Christchurch'. Someone quotes 'It's only 250 metres to empty your chemical toilet'. An elderly woman trudges through the rain pushing a trolley on which is balanced her chemical toilet. Context - Following the Christchurch earthquake of 22 February 2011 when a great deal of damage was done to the sewage system because of broken pipes thousands of chemical toilets have been distributed but now there seems to be confusion over whether it is safe to use flushing toilets when the sewage system cannot support it or whether residents should still be using chemical toilets. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

Two people peer out from underneath a table waiting for an earthquake predicted by astrologer Ken Ring. One of them says 'Load of rubbish that Ken Ring prediction eh?' and the other agrees. Context - After the two big earthquakes in Christchurch on 4 September 2010 and 22 February 2011, the so-called Moon Man, Ken Ring, is backing away from his prediction that Christchurch will be whacked by a huge earthquake on the 20th of March 2011. His claims terrified Cantabrians and led to people fleeing Christchurch. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

Shows a mobile phone with a text on it that reads 'Dear Chch (Christchurch) thinking of u (you) all xxx NZ'. Context: Refers to the commemoration events taking place in Christchurch on 22 February 2012 which is the first anniversary of the 2011 earthquake which killed 185 people. Mobile phones were instrumental in helping to locate victims and in enabling people to communicate with trapped victims. B&W and colour versions of this cartoon available Quantity: 2 digital cartoon(s).

Images, Alexander Turnbull Library

Three men chat in a pub. One of them reads a newspaper article about the Mayor of Christchurch, Bob Parker, who commented that he was scared of earthquakes when in Wellington. All three drinkers would rather be in Wellington than trapped beside Bob Parker at a dinner table. Context: Christchurch's Mayor has told the Emergency Management Conference he's scared to be in Wellington. He gave graphic descriptions of the Christchurch earthquakes, getting people to bang on the tables for 45 seconds so they could see what it felt like. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

The cartoon shows rubble and ruined buildings after the Canterbury earthquake of 4th September 2010. Rats representing 'looters' run over the buildings taking advantage as do cockroaches representing 'politics'. Refers to a certain amount of looting but also the high profiles during the aftermath of Mayor Bob Parker with local body elections only a few weeks away and PM John Key in particular. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

A television announcer sits at his desk reading the news. He says 'The shake which lasted 75 minutes and caused widespread damage in living rooms all over the country measured 5.18 on the rugby scale and was centred on Port Elizabeth in South Africa'. Context: The All Blacks lost to the Springboks 5-18 in a tri-nations test match in South Africa only a few days before the World Cup kick-off. Fans have been warned not to panic. Colour and black and white versions available Quantity: 2 digital cartoon(s).

Images, Alexander Turnbull Library

A man, half shown, sits on a loo and says 'Dang! I'm busting again! as he reaches for the toilet paper which has a different 'quake claim' printed on each section. Context - Magnitude 6.0 and 5.5 earthquakes rocked Christchurch again at 1pm and 2.20pm on 13th June 2011. These quakes follow the first earthquake on September 4th 2010 and the second on February 22nd 2011. (www.stuff.co.nz, 13 June 2011) Each time there is a significant quake more damage is done and so people have to make further insurance claims. Quantity: 1 digital cartoon(s).

Research papers, The University of Auckland Library

The performance of retrofitted unreinforced masonry (URM) bearing wall buildings in Christchurch is examined, considering ground motion recordings from multiple events. Suggestions for how the experiences in Christchurch might be relevant to retrofit practices common to New Zealand, U.S. and Canada are also provided. Whilst the poor performance of unretrofitted URM buildings in earthquakes is well known, much less is known about how retrofitted URM buildings perform when subjected to strong ground shaking.

Images, Alexander Turnbull Library

'Cappuccino dreams'. Christchurch mayoral candidates Jim Anderton and incumbent mayor Bob Parker tell constituents that they will get respectively more transparency in 'financial dealings' and in 't-shirts'. As the earthquake strikes they continue their electioneering until they are told to 'clear orf' because 'these frames lack substance'. A front-end loader begins to dismantle the structure from which they are speaking. Refers to the local body elections to take place 9th October and the Canterbury earthquake of 4th September. Published in the Presto Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

A monster cook who represents 'Mother Nature' stirs several pots as storms swirl outside the window. She has a list of recipes that read 'earthquake entree, tornado twisties, blizzard Bolognese, volcanic mudcake, flood fondue, cyclone souffle'; she says 'Mmmm what shall I cook up next?' Context - the bad weather and the Christchurch earthquake that have afflicted the South Island recently. Published in The Sunday Star Times Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

A crowd of Christchurch rugby fans wearing the red and black colours, gather to wish the Crusaders well as they leave for Australia. Someone shouts 'Red and black... It's one zone we ALL belong in!' Context - The Reds (Queensland) and Crusaders (Christchurch) played on the 11th July in the Final of the Investec Super Rugby competition at Suncorp Stadium, Brisbane. The Crusaders were narrowly beaten 18-13. The comment referring to 'one zone' relates to the dividing Christchurch, after the earthquakes, into zones labelled with different colours that indicates whether buildings have to be removed, or can be repaired or whether a decision has yet to be made or they are ok. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

The cartoon shows a camping ground full of tents and caravans and people looking glum as the rain pours down. All except one family who laugh and enjoy themselves in spite of the weather - it is because they are from Christchurch and the weather is of no consequence when they can live for a few days without fear of earthquakes. Colour and black and white versions available Quantity: 2 digital cartoon(s).

Images, Alexander Turnbull Library

Shows Minister for Christchurch Earthquake Recovery Gerry Brownlee delighted with his plan to rebuild Christchurch and to have it paid for buy the PM's casino. Context: Refers to the Christchurch Central Development Unit that Minister for Christchurch Earthquake Recovery Gerry Brownlee has put in place. Refers also to the very controversial deal that Prime Minister John Key has made with Auckland's SkyCity to the effect that SkyCity will pay the full construction cost of a new convention centre - estimated at $350 million, in return for being allowed to add more gaming tables and machines, and extending its licence beyond 2021. Colour and black and white versions of this cartoon are available Quantity: 2 digital cartoon(s).

Research papers, The University of Auckland Library

Two days after the 22 February 2011 M6.3 earthquake in Christchurch, New Zealand, three of the authors conducted a transect of the central city, with the goal of deriving an estimate of building damage levels. Although smaller in magnitude than the M7.1 4 September 2010 Darfield earthquake, the ground accelerations, ground deformation and damage levels in Christchurch central city were more severe in February 2011, and the central city was closed down to the general public. Written and photographic notes of 295 buildings were taken, including construction type, damage level, and whether the building would likely need to be demolished. The results of the transect compared favourably to Civil Defence rapid assessments made over the following month. Now, more than one year and two major aftershocks after the February 2011 earthquake these initial estimates are compared to the current demolition status to provide an updated understanding of the state of central Christchurch.

Research papers, The University of Auckland Library

Following the Christchurch earthquake of 22 February 2011 a number of researchers were sent to Christchurch, New Zealand to document the damage to masonry buildings as part of “Project Masonry”. Coordinated by the Universities of Auckland and Adelaide, researchers came from Australia, New Zealand, Canada, Italy, Portugal and the US. The types of masonry investigated were unreinforced clay brick masonry, unreinforced stone masonry, reinforced concrete masonry, residential masonry veneer and churches; masonry infill was not part of this study. This paper focuses on the progress of the unreinforced masonry (URM) component of Project Masonry. To date the research team has completed raw data collection on over 600 URM buildings in the Christchurch area. The results from this study will be extremely relevant to Australian cities since URM buildings in New Zealand are similar to those in Australia.

Images, Alexander Turnbull Library

In the top panel a kiwi reads the newspaper which has headlines reading 'Milk prices', 'BMW limos', 'Dodgy politicians', and 'Foreign despot news' and says 'Let's get this all in perspective'. In the lower panel the kiwi walks among the ruins and the graves of Christchurch and thinks 'Christchurch and Canterbury need our attention and care!!' Context - The very severe Christchurch earthquake of 22 February 2011 in which probably more than 200 people died and an enormous amount of structural damage has been done. The headlines refer to Fonterra putting a freeze on the price of milk, the government buying expensive limos (both of these making headlines because of the state of the economy) and lastly the 'foreign despot' is Gaddafi in Libya. Quantity: 1 digital cartoon(s).