This study examines the performance of nonlinear total-stress wave-propagation site response analysis for modelling site effects in physics-based ground motion simulations of the 2010-2011 Canterbury, New Zealand earthquake sequence. This approach allows for explicit modeling of 3-dimensional ground motion phenomena at the regional scale, as well as detailed site effects and soil nonlinearity at the local scale. The approach is compared to a more commonly used empirical VS30 (30 m time-averaged shear wave velocity)-based method for computing site amplification as proposed by Graves and Pitarka (2010, 2015).
Background This study examines the performance of site response analysis via nonlinear total-stress 1D wave-propagation for modelling site effects in physics-based ground motion simulations of the 2010-2011 Canterbury, New Zealand earthquake sequence. This approach allows for explicit modeling of 3D ground motion phenomena at the regional scale, as well as detailed nonlinear site effects at the local scale. The approach is compared to a more commonly used empirical VS30 (30 m time-averaged shear wave velocity)-based method for computing site amplification as proposed by Graves and Pitarka (2010, 2015), and to empirical ground motion prediction via a ground motion model (GMM).
On 14 November 2016 a magnitude Mw 7.8 earthquake struck the upper South Island of New Zealand with effects also being observed in the capital city, Wellington. The affected area has low population density but is the largest wine production region in New Zealand and also hosts the main national highway and railway routes connecting the country’s three largest cities of Auckland, Wellington and Christchurch, with Marlborough Port in Picton providing connection between the South and North Islands. These transport facilities sustained substantial earthquake related damage, causing major disruptions. Thousands of landslides and multiple new faults were counted in the area. The winery facilities and a large number of commercial buildings and building components (including brick masonry veneers, historic masonry construction, and chimneys), sustained damage due to the strong vertical and horizontal acceleration. Presented herein are field observations undertaken the day immediately after the earthquake, with the aim to document earthquake damage and assess access to the affected area.
Previous earthquakes demonstrated destructive effects of soil-structure interaction on structural response. For example, in the 1970 Gediz earthquake in Turkey, part of a factory was demolished in a town 135 km from the epicentre, while no other buildings in the town were damaged. Subsequent investigations revealed that the fundamental period of vibration of the factory was approximately equal to that of the underlying soil. This alignment provided a resonance effect and led to collapse of the structure. Another dramatic example took place in Adapazari, during the 1999 Kocaeli earthquake where several foundations failed due to either bearing capacity exceedance or foundation uplifting, consequently, damaging the structure. Finally, the Christchurch 2012 earthquakes have shown that significant nonlinear action in the soil and soil-foundation interface can be expected due to high levels of seismic excitation and spectral acceleration. This nonlinearity, in turn, significantly influenced the response of the structure interacting with the soil-foundation underneath. Extensive research over more than 35 years has focused on the subject of seismic soil-structure interaction. However, since the response of soil-structure systems to seismic forces is extremely complex, burdened by uncertainties in system parameters and variability in ground motions, the role of soil-structure interaction on the structural response is still controversial. Conventional design procedures suggest that soil-structure interaction effects on the structural response can be conservatively ignored. However, more recent studies show that soil-structure interaction can be either beneficial or detrimental, depending on the soil-structure-earthquake scenarios considered. In view of the above mentioned issues, this research aims to utilise a comprehensive and systematic probabilistic methodology, as the most rational way, to quantify the effects of soil-structure interaction on the structural response considering both aleatory and epistemic uncertainties. The goal is achieved by examining the response of established rheological single-degree-of-freedom systems located on shallow-foundation and excited by ground motions with different spectral characteristics. In this regard, four main phases are followed. First, the effects of seismic soil-structure interaction on the response of structures with linear behaviour are investigated using a robust stochastic approach. Herein, the soil-foundation interface is modelled by an equivalent linear cone model. This phase is mainly considered to examine the influence of soil-structure interaction on the approach that has been adopted in the building codes for developing design spectrum and defining the seismic forces acting on the structure. Second, the effects of structural nonlinearity on the role of soil-structure interaction in modifying seismic structural response are studied. The same stochastic approach as phase 1 is followed, while three different types of structural force-deflection behaviour are examined. Third, a systematic fashion is carried out to look for any possible correlation between soil, structural, and system parameters and the degree of soil-structure interaction effects on the structural response. An attempt is made to identify the key parameters whose variation significantly affects the structural response. In addition, it is tried to define the critical range of variation of parameters of consequent. Finally, the impact of soil-foundation interface nonlinearity on the soil-structure interaction analysis is examined. In this regard, a newly developed macro-element covering both material and geometrical soil-foundation interface nonlinearity is implemented in a finite-element program Raumoko 3D. This model is then used in an extensive probabilistic simulation to compare the effects of linear and nonlinear soil-structure interaction on the structural response. This research is concluded by reviewing the current design guidelines incorporating soil-structure interaction effects in their design procedures. A discussion is then followed on the inadequacies of current procedures based on the outcomes of this study.
Earthquakes impacting on the built environment can generate significant volumes of waste, often overwhelming existing waste management capacities. Earthquake waste can pose a public and environmental health hazard and can become a road block on the road to recovery. Specific research has been developed at the University of Canterbury to go beyond the current perception of disaster waste as a logistical hurdle, to a realisation that disaster waste management is part of the overall recovery process and can be planned for effectively. Disaster waste decision-makers, often constrained by inappropriate institutional frameworks, are faced with conflicting social, economic and environmental drivers which all impact on the overall recovery. Framed around L’Aquila earthquake, Italy, 2009, this paper discusses the social, economic and environmental effects of earthquake waste management and the impact of existing institutional frameworks (legal, financial and organisational). The paper concludes by discussing how to plan for earthquake waste management.
Knowing how to rapidly rebuild disaster-damaged infrastructure, while deciding appropriate recovery strategies and catering for future investment is a matter of core interest to government decision makers, utility providers, and business sectors. The purpose of this research is to explore the effects of decisions and outcomes for physical reconstruction on the overall recovery process of horizontal infrastructure in New Zealand using the Canterbury and Kaikoura earthquakes as cases. A mixed approach including a systematic review, questionnaire survey and semi-structured interviews is used to capture perspectives of those involved in reconstruction process and gain insights into the effect of critical elements on infrastructure downtime. Findings from this research will contribute towards advancements of a systems dynamics model considering critical decision-making variables across phases of the reconstruction process to assess how these variables affect the rebuild process and the corresponding downtime. This project will improve the ability to explore alternative resilience improvement pathways and test the efficacy of alternative means for facilitating a faster and better reconstruction process.
INTRODUCTION This project falls under the Flagship 3: Wellington Coordinated Project. It supports other projects within FP3 to create a holistic understanding of risks posed by collapsed buildings due to future earthquake/s and the secondary consequences of cordoning in the short, mid and long term. Cordoning of the Christchurch CBD for more than two years and its subsequent implications on people and businesses had a significant impact on the recovery of Christchurch. Learning from this and experiences from the Kaikōura earthquake (where cordons were also established around selected buildings, Figure 3) have highlighted the need to understand the effects of cordons and plan for it before an earthquake occurs
Recent severe earthquakes, such as the 2010-2011 Christchurch earthquake series, have put emphasis on building resilience all over the world. To achieve such resilience, procedures for low damage seismic design have been developed to satisfy both life safety requirements and the need to minimize undesirable economic effects of required building repair or structural member replacement following a major earthquake. Seismic resisting systems following this concept are expected to withstand severe earthquakes without requiring major post-earthquake repairs, using isolating mechanisms or sacrificial systems that either do not need repair or are readily repairable or replaceable. These include the sliding hinge joint with asymmetric friction connections (SHJAFCs) in beam-to-column connections of the moment resisting steel frames (MRSFs) and symmetric friction connections (SFCs) in braces of the braced frames. A 9 m tall, configurable three-storey steel framed composite floor building incorporating frictionbased connections is to be tested using two linked bi-directional shake tables at the International joint research Laboratory of Earthquake Engineering (ILEE) facilities, Shanghai, China. The structural systems are configurable, allowing different moment and braced frame structural systems tested in two horizontal directions. The structure is designed and detailed to undergo, at worst, minor damage under a planned series of severe earthquakes.
Ground motion observations from the most significant 10 events in the 2010-2011 Canterbury earthquake sequence at near-source sites are utilized to scrutinize New Zealand (NZ)-specific pseudo-spectral acceleration (SA) empirical ground motion prediction equations (GMPE) (Bradley 2010, Bradley 2013, McVerry et al. 2006). Region-specific modification factors based on relaxing the conventional ergodic assumption in GMPE development were developed for the Bradley (2010) model. Because of the observed biases with magnitude and source-to-site distance for the McVerry et al. (2006) model it is not possible to develop region-specific modification factors in a reliable manner. The theory of non-ergodic empirical ground motion prediction is then outlined, and applied to this 10 event dataset to determine systematic effects in the between- and within-event residuals which lead to modifications in the predicted median and standard deviation of the GMPE. By examining these systematic effects over sub-regions containing a total of 20 strong motion stations within the Canterbury area, modification factors for use in region-specific ground motion prediction are proposed. These modification factors, in particular, are suggested for use with the Bradley et al. (2010) model in Canterbury-specific probabilistic seismic hazard analysis (PSHA) to develop revised design response, particularly for long vibration periods.
Results from cyclic undrained direct simple shear tests on reconstituted specimens of two sands from Christchurch are compared against the liquefaction resistance inferred from CPT-based empirical liquefaction triggering methods. Limitations in existing empirical triggering relationships to capture important effects related to processes which originated test soils are highlighted and discussed.
This paper presents the preliminary findings of a study on the resilience and recovery of organisations following the Darfield earthquake in New Zealand on 4 September 2010. Sampling included organisations proximal and distal to the fault trace, organisations located within central business districts, and organisations from seven diverse industry sectors. The research captured information on the challenges to, the impacts on, and the reflections of the organisations in the first months of recovery. Organisations in central business districts and in the hospitality sector were most likely to close while organisations that had perishable stock and livestock were more heavily reliant on critical services. Staff well-being, cash flow, and customer loss were major concerns for organisations across all sectors. For all organisations, the most helpful factors in mitigating the effects of the earthquake to be their relationship with staff, the design and type of buildings, and critical service continuity or swift reinstatement of services.
The Canterbury earthquake series of 2010/2011 has turned the city of Christchurch into a full scale natural laboratory testing the structural and non-structural response of buildings under moderate to very severe earthquake shaking. The lessons learned from this, which have come at great cost socially and economically, are extremely valuable in increasing our understanding of whole building performance in severe earthquakes. Given current initiatives underway on both sides of the Tasman towards developing joint Australasian steel and composite steel/concrete design and construction standards that would span a very wide range of geological conditions and seismic zones, these lessons are relevant to both countries. This paper focusses on the performance of steel framed buildings in Christchurch city, with greatest emphasis on multi-storey buildings, but also covering single storey steel framed buildings and light steel framed housing. It addresses such issues as the magnitude and structural impact of the earthquake series, importance of good detailing, lack of observed column base hinging, the excellent performance of composite floors and it will briefly cover research underway to quantify some of these effects for use in design.
The Avon-Heathcote Estuary is of significant value to Christchurch due to its high productivity, biotic diversity, proximity to the city, and its cultural, recreational and aesthetic qualities. Nonetheless, it has been subjected to decades of degradation from sewage wastewater discharges and encroaching urban development. The result was a eutrophied estuary, high in nitrogen, affected by large blooms of nuisance macroalgae and covered by degraded sediments. In March 2010, treated wastewater was diverted from the estuary to a site 3 km offshore. This quickly reduced water nitrogen by 90% within the estuary and, within months, there was reduced production of macroalgae. However, a series of earthquakes beginning in September 2010 brought massive changes: tilting of the estuary, changes in channels and water flow, and a huge influx of liquefied sediments that covered up to 65% of the estuary floor. Water nitrogen increased due to damage to sewage infrastructure and the diversion pipeline being turned off. Together, these drastically altered the estuarine ecosystem. My study involves three laboratory and five in situ experiments that investigate the base of the food chain and responses of benthic microalgae to earthquake-driven sediment and nutrient changes. It was predicted that the new sediments would be coarser and less contaminated with organic matter and nutrients than the old sediments, would have decreased microalgal biomass, and would prevent invertebrate grazing and bioturbation activities. It was believed that microalgal biomass would become similar across new and old sediments types as the unstable new sediments were resuspended and distributed over the old sediments. Contact cores of the sediment were taken at three sites, across a eutrophication gradient, monthly from September 2011 to March 2012. Extracted chlorophyll a pigments showed that microalgal biomass was generally lower on new liquefied sediments compared to old sediments, although there was considerable site to site variation, with the highly eutrophic sites being the most affected by the emergence of the new sediments. Grazer experiments showed that invertebrates had both positive and negative site-specific effects on microalgal biomass depending on their identity. At one site, new sediments facilitated grazing by Amphibola crenata, whereas at another site, new sediments did not alter the direct and indirect effects of invertebrates (Nicon aestuariensis, Macropthalmus hirtipes, and A. crenata) on microalgae. From nutrient addition experiments it was clear that benthic microalgae were able to use nutrients from within both old and new sediments equally. This implied that microalgae were reducing legacy nutrients in both sediments, and that they are an important buffer against eutrophication. Therefore, in tandem with the wastewater diversion, they could underpin much of the recovery of the estuary. Overall, the new sediments were less favourable for benthic microalgal growth and recolonisation, but were less contaminated than old sediments at highly eutrophic sites. Because the new sediments were less contaminated than the old sediments, they could help return the estuary to a noneutrophic state. However, if the new sediments, which are less favourable for microalgal growth, disperse over the old sediments at highly eutrophic sites, they could become contaminated and interfere with estuarine recovery. Therefore, recovery of microalgal communities and the estuary was expected to be generally long, but variable and site-specific, with the least eutrophic sites recovering quickly, and the most eutrophic sites taking years to return to a pre-earthquake and non-eutrophied state. changes in channels and water flow, and a huge influx of liquefied sediments that covered up to 65% of the estuary floor. Water nitrogen increased due to damage to sewage infrastructure and the diversion pipeline being turned off. Together, these drastically altered the estuarine ecosystem. My study involves three laboratory and five in situ experiments that investigate the base of the food chain and responses of benthic microalgae to earthquake-driven sedimen tand nutrient changes. It was predicted that the new sediments would be coarser and less contaminated with organic matter and nutrients than the old sediments, would have decreased microalgal biomass, and would prevent invertebrate grazing and bioturbation activities. It was believed that microalgal biomass would become similar across new and old sediments types as the unstable new sediments were resuspended and distributed over the old sediments. Contact cores of the sediment were taken at three sites, across a eutrophication gradient, monthly from September 2011 to March 2012. Extracted chlorophyll a pigments showed that microalgal biomass was generally lower on new liquefied sediments compared to old sediments, although there was considerable site to site variation, with the highly eutrophic sites being the most affected by the emergence of the new sediments. Grazer experiments showed that invertebrates had both positive and negative site-specific effects on microalgal biomass depending on their identity. At one site, new sediments facilitated grazing by Amphibola crenata, whereas at another site, new sediments did not alter the direct and indirect effects of invertebrates (Nicon aestuariensis, Macropthalmus hirtipes, and A. crenata) on microalgae. From nutrient addition experiments it was clear that benthic microalgae were able to use nutrients from within both old and new sediments equally. This implied that microalgae were reducing legacy nutrients in both sediments, and that they are
The question of whether forced relocation is beneficial or detrimental to the displaced households is a controversial and important policy question. After the 2011 earthquake in Christchurch, the government designated some of the worst affected areas as Residential Red Zones. Around 20,000 people were forced to move out of these Residential Red Zone areas, and were compensated for that. The objective of this paper is twofold. First, we aim to estimate the impact of relocation on the displaced households in terms of their income, employment, and their mental and physical health. Second, we evaluate whether the impact of relocation varies by the timing of to move, the destination (remaining within the Canterbury region or moving out of it) and demographic factors (gender, age, ethnicity). StatisticsNZ’s Integrated Data Infrastructure (IDI) from 2008 to 2017, which includes data on all households in Canterbury, and a difference-in-difference (DID) technique is used to answer these questions. We find that relocation has a negative impact on the income of the displaced household group. This adverse impact is more severe for later movers. Compared to the control group (that was not relocated), the income of relocated households was reduced by 3% for people who moved immediately after the earthquake in 2011, and 14% for people who moved much later in 2015.
Axial elongation of reinforced concrete (RC) plastic hinges has previously been observed in a range of laboratory experiments, and more recently was observed in several Christchurch buildings following the 2010/2011 Canterbury earthquakes. Axial restraint to plastic hinges is provided by adjacent structural components such as floors as the plastic hinges elongate, which can significantly alter the performance of the plastic hinge and potentially invalidate the capacity design strength hierarchy of the building. Coupling beams in coupled wall systems are particularly susceptible to axial restraint effects due to their importance in the strength hierarchy, the high ductility demands that they experience, and the large stiffness of bounding walls. From computational modelling it has been found that ignoring axial restraint effects when designing coupled walls can result in significantly increased strength, reduced ductility and reduced energy dissipation capacity. The complexity of the topic merits further research to better account for realistic restraint effects when designing coupled walls.
We present initial results from a set of three-dimensional (3D) deterministic earthquake ground motion simulations for the northern Canterbury plains, Christchurch and the Banks Peninsula region, which explicitly incorporate the effects of the surface topography. The simu-lations are done using Hercules, an octree-based finite-element parallel software for solving 3D seismic wave propagation problems in heterogeneous media under kinematic faulting. We describe the efforts undertaken to couple Hercules with the South Island Velocity Model (SIVM), which included changes to the SIVM code in order to allow for single repetitive que-ries and thus achieve a seamless finite-element meshing process within the end-to-end ap-proach adopted in Hercules. We present our selection of the region of interest, which corre-sponds to an area of about 120 km × 120 km, with the 3D model reaching a depth of 60 km. Initial simulation parameters are set for relatively high minimum shear wave velocity and a low maximum frequency, which we are progressively scaling up as computing resources permit. While the effects of topography are typically more important at higher frequencies and low seismic velocities, even at this initial stage of our efforts (with a maximum of 2 Hz and a mini-mum of 500 m/s), it is possible to observe the importance of the topography in the response of some key locations within our model. To highlight these effects we compare the results of the 3D topographic model with respect to those of a flat (squashed) 3D model. We draw rele-vant conclusions from the study of topographic effects during earthquakes for this region and describe our plans for future work.
Rapid, reliable information on earthquake-affected structures' current damage/health conditions and predicting what would happen to these structures under future seismic events play a vital role in accelerating post-event evaluations, leading to optimized on-time decisions. Such rapid and informative post-event evaluations are crucial for earthquake-prone areas, where each earthquake can potentially trigger a series of significant aftershocks, endangering the community's health and wealth by further damaging the already-affected structures. Such reliable post-earthquake evaluations can provide information to decide whether an affected structure is safe to stay in operation, thus saving many lives. Furthermore, they can lead to more optimal recovery plans, thus saving costs and time. The inherent deficiency of visual-based post-earthquake evaluations and the importance of structural health monitoring (SHM) methods and SHM instrumentation have been highlighted within this thesis, using two earthquake-affected structures in New Zealand: 1) the Canterbury Television (CTV) building, Christchurch; 2) the Bank of New Zealand (BNZ) building, Wellington. For the first time, this thesis verifies the theoretically- and experimentally validated hysteresis loop analysis (HLA) SHM method for the real-world instrumented structure of the BNZ building, which was damaged severely due to three earthquakes. Results indicate the HLA-SHM method can accurately estimate elastic stiffness degradation for this reinforced concrete (RC) pinched structure across the three earthquakes, which remained unseen until after the third seismic event. Furthermore, the HLA results help investigate the pinching effects on the BNZ building's seismic response. This thesis introduces a novel digital clone modelling method based on the robust and accurate SHM results delivered by the HLA method for physical parameters of the monitored structure and basis functions predicting the changes of these physical parameters due to future earthquake excitations. Contrary to artificial intelligence (AI) based predictive methods with black-box designs, the proposed predictive method is entirely mechanics-based with an explicitly-understandable design, making them more trusted and explicable to stakeholders engaging in post-earthquake evaluations, such as building owners and insurance firms. The proposed digital clone modelling framework is validated using the BNZ building and an experimental RC test structure damaged severely due to three successive shake-table excitations. In both structures, structural damage intensifies the pinching effects in hysteresis responses. Results show the basis functions identified from the HLA-SHM results for both structures under Event 1 can online estimate structural damage due to subsequent Events 2-3 from the measured structural responses, making them valuable tool for rapid warning systems. Moreover, the digital twins derived for these two structures under Event 1 can successfully predict structural responses and damage under Events 2-3, which can be integrated with the incremental dynamic analysis (IDA) method to assess structural collapse and its financial risks. Furthermore, it enables multi-step IDA to evaluate earthquake series' impacts on structures. Overall, this thesis develops an efficient method for providing reliable information on earthquake-affected structures' current and future status during or immediately after an earthquake, considerably guaranteeing safety. Significant validation is implemented against both experimental and real data of RC structures, which thus clearly indicate the accurate predictive performance of this HLA-based method.
This article argues that teachers deserve more recognition for their roles as first responders in the immediate aftermath of a disaster and for the significant role they play in supporting students and their families through post-disaster recovery. The data are drawn from a larger study, 'Christchurch Schools Tell Their Earthquake Stories' funded by the United Nations Educational, Scientific and Cultural Organisation and the University of Auckland, in which schools were invited to record their earthquake stories for themselves and for historical archives. Data were gathered from five primary schools between 2012 and 2014. Methods concerned mainly semi-structured individual or group interviews and which were analysed thematically. The approach was sensitive, flexible and participatory with each school being able to choose its focus, participants and outcome. Participants from each school generally included the principal and a selection of teachers, students and parents. In this study, the data relating to the roles of teachers were separated out for closer analysis. The findings are presented as four themes: immediate response; returning to (new) normal; care and support; and long term effects.
This paper investigates the effects of variability in source rupture parameters on site-specific physics-based simulated ground motions, ascertained through the systematic analysis of ground motion intensity measures. As a preliminary study, we consider simulations of the 22 February 2011 Christchurch earthquake using the Graves and Pitarka (2015) methodology. The effects of source variability are considered via a sensitivity study in which parameters (hypocentre location, earthquake magnitude, average rupture velocity, fault geometry and the Brune stress parameter) are individually varied by one standard deviation. The sensitivity of simulated ground motion intensity measures are subsequently compared against observational data. The preliminary results from this study indicate that uncertainty in the stress parameter and the rupture velocity have the most significant effect on the high frequency amplitudes. Conversely, magnitude uncertainty was found to be most influential on the spectral acceleration amplitudes at low frequencies. Further work is required to extend this preliminary study to exhaustively consider more events and to include parameter covariance. The ultimate results of this research will assist in the validation of the overall simulation method’s accuracy in capturing various rupture parameters, which is essential for the use of simulated ground motion models in probabilistic seismic hazard analysis.
During 2010 and 2011, major earthquakes caused widespread damage and the deaths of 185 people in the city of Christchurch. Damaged school buildings resulted in state intervention which required amendment of the Education Act of 1989, and the development of ‘site sharing agreements’ in undamaged schools to cater for the needs of students whose schools had closed. An effective plan was also developed for student assessment through establishing an earthquake impaired derived grade process. Previous research into traditional explanations of educational inequalities in the United Kingdom, the United States of America, and New Zealand were reviewed through various processes within three educational inputs: the student, the school and the state. Research into the impacts of urban natural disasters on education and education inequalities found literature on post disaster education systems but nothing could be found that included performance data. The impacts of the Canterbury earthquakes on educational inequalities and achievement were analysed over 2009-2012. The baseline year was 2009, the year before the first earthquake, while 2012 is seen as the recovery year as no schools closed due to seismic events and there was no state intervention into the education of the region. National Certificate of Educational Achievement (NCEA) results levels 1-3 from thirty-four secondary schools in the greater Christchurch region were graphed and analysed. Regression analysis indicates; in 2009, educational inequalities existed with a strong positive relationship between a school’s decile rating and NCEA achievement. When schools were grouped into decile rankings (1-10) and their 2010 NCEA levels 1-3 results were compared with the previous year, the percentage of change indicates an overall lower NCEA achievement in 2010 across all deciles, but particularly in lower decile schools. By contrast, when 2011 NCEA results were compared with those of 2009, as a percentage of change, lower decile schools fared better. Non site sharing schools also achieved higher results than site sharing schools. State interventions, had however contributed towards student’s achieving national examinations and entry to university in 2011. When NCEA results for 2012 were compared to 2009 educational inequalities still exist, however in 2012 the positive relationship between decile rating and achievement is marginally weaker than in 2009. Human ethics approval was required to survey one Christchurch secondary school community of students (aged between 12 and 18), teachers and staff, parents and caregivers during October 2011. Participation was voluntary and without incentives, 154 completed questionnaires were received. The Canterbury earthquakes and aftershocks changed the lives of the research participants. This school community was displaced to another school due to the Christchurch earthquake on 22 February 2011. Research results are grouped under four geographical perspectives; spatial impacts, socio-economic impacts, displacement, and health and wellbeing. Further research possibilities include researching the lag effects from the Canterbury earthquakes on school age children.
The Canterbury region of New Zealand experienced four earthquakes greater than MW 6.0 between September 2010 and December 2011. This study employs system dynamics as well as hazard, recovery and organisational literature and brings together data collected via surveys, case studies and interviews with organisations affected by the earthquakes. This is to show how systemic interactions and interdependencies within and between industry and geographic sectors affect their recovery post-disaster. The industry sectors in the study are: construction for its role in the rebuild, information and communication technology which is a regional high-growth industry, trucking for logistics, critical infrastructure, fast moving consumer goods (e.g. supermarkets) and hospitality to track recovery through non-discretionary and discretionary spend respectively. Also in the study are three urban centres including the region’s largest Central Business District, which has been inaccessible since the earthquake of 22 February 2011 to the time of writing in February 2013. This work also highlights how earthquake effects propagated between sectors and how sectors collaborated to mitigate difficulties such as product demand instability. Other interacting factors are identified that influence the recovery trajectories of the different industry sectors. These are resource availability, insurance payments, aid from central government, and timely and quality recovery information. This work demonstrates that in recovering from disaster it is crucial for organisations to identify what interacting factors could affect their operations. Also of importance are efforts to reduce the organisation’s vulnerability and increase their resilience to future crises and in day-to-day operations. Lastly, the multi-disciplinary approach to understanding the recovery and resilience of organisations and industry sectors after disaster, leads to a better understanding of effects as well as more effective recovery policy.
Christchurch has experienced a series of over 13,500 earthquakes between September 2010 and January 2012. Some children who have been exposed to earthquakes may experience post-traumatic stress disorder symptoms (PTSD) including difficulty concentrating, feeling anxious, restlessness and confusion. Other children may be resilient to the effects of disaster. Western models of resilience relate to a child’s social support and their capacity to cope. The Māori model of wellbeing relates to whanau (family), wairua (spiritual connections), tinana (the physical body) and hinengaro (the mind and emotions). Children’s concepts of helping, caring and learning may provide insight into resilience without introducing the topic of earthquakes into the conversation, which in itself may provoke an episode of stress. Many researchers have studied the effects of earthquakes on children. However, few studies have examined positive outcomes and resilience or listened to the children’s voices. The objective of this study was to listen to the voices of children who experienced the Canterbury earthquake period in order to gain a deeper understanding of the ideas associated resilience. Individual interviews were conducted with 17 five-year-old participants during their first term of primary school. After the interviews, the teacher shared demographic information and reports on the children’s stress and coping. Six children were identified as New Zealand European and eleven children identified as New Zealand Māori. Children had different views of helping, caring and learning. Themes of resilience from Western and Kaupapa Māori models were identified in transcripts of the children's voices and drawings. Māori children voiced more themes of resilience associated with the Western model, and in the Tapa Whā model, Māori children's transcripts were more likely to be inclusive of all four components of well-being. How five-year-old children, having experienced an earthquake disaster during their preschool years, talk or draw pictures about helping, caring and learning can provide insight into resilience, especially in situations where it is not advisable to re-traumatise children by discussing the disaster event. Future research should interview parents/caregivers and whānau to gain further insights. Considering information from both a Western and a Tapa Whā perspective can also provide new insights into resilience in young children. A limitation of this study is that qualitative studies are not always free from a researcher’s interpretation and are, therefore, subjective.
A linear and non-linear model are developed to analyze the structural impact and response of two single degree of freedom structures, representing adjacent buildings or bridge sections. Different impact coefficients of restitution, normalized distances between structures and a range of different structural periods are considered. The probability of impact and the displacement changes that can result from these collisions are computed. The likelihood of an increase in displacement is quantified in a probabilistic sense. A full matrix of response simulations are performed to individually investigate and delineate the effects of inter-structure gap-ratio, period ratios, structural non-linearity and impact elasticity. Column inelasticity is incorporated through the use of a Ramberg-Osgood type hysteresis rule. The minimum normalized distance, or gap-ratio, required between two structures to ensure that the likelihood of increased displacement of more than 10% for either structure for 90% of the given earthquake ground motions is assessed as one of many possible design risk bounds. Increased gap ratio, defined as a percentage of spectral displacement, is shown to reduce the likelihood of impact, as well as close structural periods. Larger differences in the relative periods of the two structures were seen to significantly increase the likelihood of impact. Inclusion of column inelasticity and higher plasticity of impact reduce displacement increases from impact and thus possible further damage to the structures. Such information can be used as a guideline to manage undesirable effects of impact in design - a factor that has been observed to be very important during the recent Canterbury, New Zealand Earthquakes.
This research employs a deterministic seismic risk assessment methodology to assess the potential damage and loss at meshblock level in the Christchurch CBD and Mount Pleasant primarily due to building damage caused by earthquake ground shaking. Expected losses in terms of dollar value and casualties are calculated for two earthquake scenarios. Findings are based on: (1) data describing the earthquake ground shaking and microzonation effects; (2) an inventory of buildings by value, floor area, replacement value, occupancy and age; (3) damage ratios defining the performance of buildings as a function of earthquake intensity; (4) daytime and night-time population distribution data and (5) casualty functions defining casualty risk as a function of building damage. A GIS serves as a platform for collecting, storing and analyzing the original and the derived data. It also allows for easy display of input and output data, providing a critical functionality for communication of outcomes. The results of this study suggest that economic losses due to building damage in the Christchurch CBD and Mount Pleasant will possibly be in the order of $5.6 and $35.3 million in a magnitude 8.0 Alpine fault earthquake and a magnitude 7.0 Ashley fault earthquake respectively. Damage to non-residential buildings constitutes the vast majority of the economic loss. Casualty numbers are expected to be between 0 and 10.
The Canterbury Earthquakes of 2010-2011, in particular the 4th September 2010 Darfield earthquake and the 22nd February 2011 Christchurch earthquake, produced severe and widespread liquefaction in Christchurch and surrounding areas. The scale of the liquefaction was unprecedented, and caused extensive damage to a variety of man-made structures, including residential houses. Around 20,000 residential houses suffered serious damage as a direct result of the effects of liquefaction, and this resulted in approximately 7000 houses in the worst-hit areas being abandoned. Despite the good performance of light timber-framed houses under the inertial loads of the earthquake, these structures could not withstand the large loads and deformations associated with liquefaction, resulting in significant damage. The key structural component of houses subjected to liquefaction effects was found to be their foundations, as these are in direct contact with the ground. The performance of house foundations directly influenced the performance of the structure as a whole. Because of this, and due to the lack of research in this area, it was decided to investigate the performance of houses and in particular their foundations when subjected to the effects of liquefaction. The data from the inspections of approximately 500 houses conducted by a University of Canterbury summer research team following the 4th September 2010 earthquake in the worst-hit areas of Christchurch were analysed to determine the general performance of residential houses when subjected to high liquefaction loads. This was followed by the detailed inspection of around 170 houses with four different foundation types common to Christchurch and New Zealand: Concrete perimeter with short piers constructed to NZS3604, concrete slab-on-grade also to NZS3604, RibRaft slabs designed by Firth Industries and driven pile foundations. With a focus on foundations, floor levels and slopes were measured, and the damage to all areas of the house and property were recorded. Seven invasive inspections were also conducted on houses being demolished, to examine in more detail the deformation modes and the causes of damage in severely affected houses. The simplified modelling of concrete perimeter sections subjected to a variety of liquefaction-related scenarios was also performed, to examine the comparative performance of foundations built in different periods, and the loads generated under various bearing loss and lateral spreading cases. It was found that the level of foundation damage is directly related to the level of liquefaction experienced, and that foundation damage and liquefaction severity in turn influence the performance of the superstructure. Concrete perimeter foundations were found to have performed most poorly, suffering high local floor slopes and being likely to require foundation repairs even when liquefaction was low enough that no surface ejecta was seen. This was due to their weak, flexible foundation structure, which cannot withstand liquefaction loads without deforming. The vulnerability of concrete perimeter foundations was confirmed through modelling. Slab-on-grade foundations performed better, and were unlikely to require repairs at low levels of liquefaction. Ribraft and piled foundations performed the best, with repairs unlikely up to moderate levels of liquefaction. However, all foundation types were susceptible to significant damage at higher levels of liquefaction, with maximum differential settlements of 474mm, 202mm, 182mm and 250mm found for concrete perimeter, slab-on-grade, ribraft and piled foundations respectively when subjected to significant lateral spreading, the most severe loading scenario caused by liquefaction. It was found through the analysis of the data that the type of exterior wall cladding, either heavy or light, and the number of storeys, did not affect the performance of foundations. This was also shown through modelling for concrete perimeter foundations, and is due to the increased foundation strengths provided for heavily cladded and two-storey houses. Heavy roof claddings were found to increase the demands on foundations, worsening their performance. Pre-1930 concrete perimeter foundations were also found to be very vulnerable to damage under liquefaction loads, due to their weak and brittle construction.
Coastal and river environments are exposed to a number of natural hazards that have the potential to negatively affect both human and natural environments. The purpose of this research is to explain that significant vulnerabilities to seismic hazards exist within coastal and river environments and that coasts and rivers, past and present, have played as significant a role as seismic, engineering or socio-economic factors in determining the impacts and recovery patterns of a city following a seismic hazard event. An interdisciplinary approach was used to investigate the vulnerability of coastal and river areas in the city of Christchurch, New Zealand, following the Canterbury Earthquake Sequence, which began on the 4th of September 2010. This information was used to identify the characteristics of coasts and rivers that make them more susceptible to earthquake induced hazards including liquefaction, lateral spreading, flooding, landslides and rock falls. The findings of this research are applicable to similar coastal and river environments elsewhere in the world where seismic hazards are also of significant concern. An interdisciplinary approach was used to document and analyse the coastal and river related effects of the Canterbury earthquake sequence on Christchurch city in order to derive transferable lessons that can be used to design less vulnerable urban communities and help to predict seismic vulnerabilities in other New Zealand and international urban coastal and river environments for the future. Methods used to document past and present features and earthquake impacts on coasts and rivers in Christchurch included using maps derived from Geographical Information Systems (GIS), photographs, analysis of interviews from coastal, river and engineering experts, and analysis of secondary data on seismicity, liquefaction potential, geology, and planning statutes. The Canterbury earthquake sequence had a significant effect on Christchurch, particularly around rivers and the coast. This was due to the susceptibility of rivers to lateral spreading and the susceptibility of the eastern Christchurch and estuarine environments to liquefaction. The collapse of river banks and the extensive cracking, tilting and subsidence that accompanied liquefaction, lateral spreading and rock falls caused damage to homes, roads, bridges and lifelines. This consequently blocked transportation routes, interrupted electricity and water lines, and damaged structures built in their path. This study found that there are a number of physical features of coastal and river environments from the past and the present that have induced vulnerabilities to earthquake hazards. The types of sediments found beneath eastern Christchurch are unconsolidated fine sands, silts, peats and gravels. Together with the high water tables located beneath the city, these deposits made the area particularly susceptible to liquefaction and liquefaction-induced lateral spreading, when an earthquake of sufficient size shook the ground. It was both past and present coastal and river processes that deposited the types of sediments that are easily liquefied during an earthquake. Eastern Christchurch was once a coastal and marine environment 6000 years ago when the shoreline reached about 6 km inland of its present day location, which deposited fine sand and silts over this area. The region was also exposed to large braided rivers and smaller spring fed rivers, both of which have laid down further fine sediments over the following thousands of years. A significant finding of this study is the recognition that the Canterbury earthquake sequence has exacerbated existing coastal and river hazards and that assessments and monitoring of these changes will be an important component of Christchurch’s future resilience to natural hazards. In addition, patterns of recovery following the Canterbury earthquakes are highlighted to show that coasts and rivers are again vulnerable to earthquakes through their ability to recovery. This city’s capacity to incorporate resilience into the recovery efforts is also highlighted in this study. Coastal and river areas have underlying physical characteristics that make them increasingly vulnerable to the effects of earthquake hazards, which have not typically been perceived as a ‘coastal’ or ‘river’ hazard. These findings enhance scientific and management understanding of the effects that earthquakes can have on coastal and river environments, an area of research that has had modest consideration to date. This understanding is important from a coastal and river hazard management perspective as concerns for increased human development around coastlines and river margins, with a high seismic risk, continue to grow.
The self-regulation approach to educating parents focusses on promoting parenting confidence, independence, and the ability to solve future problems. As parents learn the skills to modify their own behaviour, in turn, they aim to foster self-regulation in their children/adolescents. A need had been identified by Christchurch school principals for the Ministry of Education to respond to the post-earthquake stress in local families. The aim of this study was to investigate if a parenting programme was effective in promoting parental self-management skills and adolescent behaviour change in Christchurch families affected by earthquakes between 2010 and 2012. A single case research design was used to follow five families with adolescents (12-16 years old) as they participated in a Group Teen Triple P – Positive Parenting Programme. Measures of self-management skill acquisition were taken during three family discussions (pre-intervention, mid-intervention, and post-intervention) and during the three telephone consultations (Sessions 5-7). Adolescent target behaviour tallies were also analysed for change. The main findings showed that parental self-management skill acquisition increased over-time accompanied by positive change in adolescent behaviour. Additionally, the results suggested that higher rates and levels of self-management skill acquisition in the parents were associated with greater improvements in adolescent behaviour. This study demonstrated that Group Teen Triple P – Positive Parenting Programme was effective in promoting self-management competencies in parents and behaviour change in adolescents.
Buildings subject to earthquake shaking will tend to move not only horizontally but also rotate in plan. In-plan rotation is known as “building torsion” and it may occur for a variety of reasons, including stiffness and strength eccentricity and/or torsional effects from ground motions. Methods to consider torsion in structural design standards generally involve analysis of the structure in its elastic state. This is despite the fact that the structural elements can yield, thereby significantly altering the building response and the structural element demands. If demands become too large, the structure may collapse. While a number of studies have been conducted into the behavior of structures considering inelastic building torsion, there appears to be no consensus that one method is better than another and as a result, provisions within current design standards have not adopted recent proposals in the literature. However, the Canterbury Earthquakes Royal Commission recently made the recommendation that provisions to account for inelastic torsional response of buildings be introduced within New Zealand building standards. Consequently, this study examines how and to what extent the torsional response due to system eccentricity may affect the seismic performance of a building and considers what a simple design method should account for. It is concluded that new methods should be simple, be applicable to both the elastic and inelastic range of response, consider bidirectional excitation and include guidance for multi-story systems.
In this paper, we perform hybrid broadband (0-10 Hz) ground motion simulations for the ten most significant events (Mw 4.7-7.1) in the 2010-2011 Canterbury earthquake sequence. Taking advantage of having repeated recordings at same stations, we validate our simulations using both recordings and an empirically-developed ground motion prediction equation (GMPE). The simulation clearly captures the sedimentary basin amplification and the rupture directivity effects. Quantitative comparisons of the simulations with both recordings and the GMPE, as well as analyses of the total residuals (indicating model bias) show that simulations perform better than the empirical GMPE, especially for long period. To scrutinize the ground motion variability, we partitioned the total residuals into different components. The total residual appears to be unbiased, and the use of a 3D velocity structure reduces the long period systematic bias particularly for stations located close to the Banks Peninsula volcanic area.
This study explicitly investigates uncertainties in physics-based ground motion simulation validation for earthquakes in the Canterbury region. The simulations utilise the Graves and Pitarka (2015) hybrid methodology, with separately quantified parametric uncertainties in the comprehensive physics and simplified physics components of the model. The study is limited to the simulation of 148 small magnitude (Mw 3.5 – 5) earthquakes, with a point source approximation for the source rupture representations, which also enables a focus on a small number of relevant uncertainties. The parametric uncertainties under consideration were selected through sensitivity analysis, and specifically include: magnitude, Brune stress parameter and high frequency rupture velocity. Twenty Monte Carlo realisations were used to sample parameter uncertainties for each of the 148 events. Residuals associated with the following intensity measures: spectral acceleration, peak ground velocity, arias intensity and significant duration, were ascertained. Using these residuals, validation was performed through assessment of systematic biases in site and source terms from mixed-effects regression. Based on the results to date, initial standard deviation recommendations for parameter uncertainties, based on the Canterbury simulations have been obtained. This work ultimately provides an initial step toward explicit incorporation of modelling uncertainty in simulated ground motion predictions for future events, which will improve the use of simulation models in seismic hazard analysis. We plan to subsequently assess uncertainties for larger magnitude events with more complex ruptures, and events across a larger geographic region, as well as uncertainties due to path attenuation, site effects, and more general model epistemic uncertainties.
