Christchurch Earthquake Research Articles

Life-cycle analysis (LCA) to restore community building portfolios by building back better I: Building portfolio LCA

In recent years, the United States and other countries have experienced catastrophic consequences of severe natural hazards, e.g. the 2005 Hurricane Katrina, the 2011 Christchurch Earthquake, and the 2011 Great East Japan Earthquake and Tsunami. These consequences motivate the question: How should a community’s damaged building portfolio be reconstructed efficiently to enhance its performance under future hazard events and meet the resilience goals of the community? The relatively recent notion of Building Back Better requires a quantitative methodology that can address each phase of building portfolio recovery following a severe hazard event and provide decision support to best enhance the performance of the portfolio under future hazards. This study extends notions of life-cycle analysis from individual buildings to building portfolios to support post-hazard reconstruction decisions at the community level. The building portfolio expected life-cycle cost and cumulative prospect value are adopted as decision metrics which reflect varying degrees of risk aversion on the part of community decision-makers. The applicability of these building portfolio life-cycle analyses and some key aspects in their implementation are explored using a moderate-sized community that is susceptible to extreme earthquake hazards.

Eco-rubber Seismic-Isolation Foundation Systems: A Sustainable Solution for the New Zealand Context

The 2010 and 2011 Christchurch earthquakes proved that a shift is necessary in the current design practice of structures to achieve better seismic performance. Moreover, environmental concerns have prompted civil engineers to identify viable ways to reuse waste tyres through engineering projects. In this context, a multi-disciplinary geo-structural–environmental engineering project funded by the Ministry of Business Innovation and Employment is being carried out at the University of Canterbury in New Zealand. The project aims to develop a foundation system characterised by: (a) granulated tyre rubber mixed with gravelly soils to be placed beneath the structure, with the goal of damping part of the seismic energy before it reaches the superstructure; and (b) a basement raft made of steel-fibre-reinforced rubberised concrete (SFRRuC) to enhance the flexibility of the foundation under differential displacement demand. An overview of the material properties of the gravel–rubber and SFRRuC mixtures is also presented.

Using High Resolution Optical Imagery to Detect Earthquake-Induced Liquefaction: The 2011 Christchurch Earthquake

Using automated supervised methods with satellite and aerial imageries for liquefaction mapping is a promising step in providing detailed and region-scale maps of liquefaction extent immediately after an earthquake. The accuracy of these methods depends on the quantity and quality of training samples and the number of available spectral bands. Digitizing a large number of high-quality training samples from an event may not be feasible in the desired timeframe for rapid response as the training pixels for each class should be typical and accurately represent the spectral diversity of that specific class. To perform automated classification for liquefaction detection, we need to understand how to build the optimal and accurate training dataset. Using multispectral optical imagery from the 22 February, 2011 Christchurch earthquake, we investigate the effects of quantity of high-quality training pixel samples as well as the number of spectral bands on the performance of a pixel-based parametric supervised maximum likelihood classifier for liquefaction detection. We find that the liquefaction surface effects are bimodal in terms of spectral signature and therefore, should be classified as either wet liquefaction or dry liquefaction. This is due to the difference in water content between these two modes. Using 5-fold cross-validation method, we evaluate performance of the classifier on datasets with different pixel sizes of 50, 100, 500, 2000, and 4000. Also, the effect of adding spectral information was investigated by adding once only the near infrared (NIR) band to the visible red, green, and blue (RGB) bands and the other time using all available 8 spectral bands of the World-View 2 satellite imagery. We find that the classifier has high accuracies (75%–95%) when using the 2000 pixels-size dataset that includes the RGB+NIR spectral bands and therefore, increasing to 4000 pixels-size dataset and/or eight spectral bands may not be worth the required time and cost. We also investigate accuracies of the classifier when using aerial imagery with same number of training pixels and either RGB or RGB+NIR bands and find that the classifier accuracies are higher when using satellite imagery with same number of training pixels and spectral information. The classifier identifies dry liquefaction with higher user accuracy than wet liquefaction across all evaluated scenarios. To improve classification performance for wet liquefaction detection, we also investigate adding geospatial information of building footprints to improve classification performance. We find that using a building footprint mask to remove them from the classification process, increases wet liquefaction user accuracy by roughly 10%.

A data-driven approach for estimating airport efficiency under endogeneity: An application to New Zealand airports

Airport efficiency is commonly estimated via data envelopment analysis (DEA). This data-driven non-parametric approach is more flexible than the parametric approach, because it does not require an a priori function for the frontier or a very big sample size. However, DEA loses its discriminatory power when the number of observed airports is small compared with the number of airport inputs and outputs examined, particularly when examining airports within a country. In addition, the endogeneity problem may exist if one attempts to examine the determinants of airport efficiency. This study used the Slack-Based Measure (SBM) DEA-Window Analysis model to address the small sample issue during the first-stage analysis and used an instrumental variable (IV) in the Tobit model to solve the endogeneity issue during the second-stage analysis. Data from a sample of 11 New Zealand airports between 2006 and 2017 were used for analysis. The key findings showed the positive impact of tourism, regional economic development, an airport's domestic networks, airport privatisation, low-cost carrier services and the Christchurch earthquakes on New Zealand airports' performance and efficiency, whereas an airport's international networks has a negative impact. The literature contribution and policy implications are also discussed.

Developing community disaster resilience through preparedness

Disasters have the potential to cause great devastation, such as significant human, material and environmental loss. Due to the increase in disaster frequency and impacts, there has been a shift in focus from disaster recovery and response to disaster prevention. Preventative disaster management is essential in reducing and eliminating community disaster risk exposure. This paper conducts a comparative analysis of three past events including the 2011 Queensland floods, the Harrietville Community Emergency Management Plan and the Christchurch and Japan earthquakes. By combining the existing literature, secondary qualitative data analysis, a conceptual model of disaster management has been developed. The findings of this research include; the development of a conceptual model that present new concepts to improve the community resilience capabilities; identification of effective methodologies for developing community resilience; the potential implementation of social media as a preparedness strategy; and discussion on community empowerment and a shared responsibility amongst all agencies.

Redrawing of a Housing Market: Insurance Payouts and Housing Market Recovery in the Wake of the Christchurch Earthquake of 2011

On the 22nd of February 2011, much of the residential housing stock in the city of Christchurch, New Zealand, was damaged by an unusually destructive earthquake. Almost all of the houses were insured. We ask whether insurance was able to mitigate the damage adequately, or whether the damage from the earthquake, and the associated insurance payments, led to a spatial re-ordering of the housing market in the city. We find a negative correlation between insurance pay-outs and house prices at the local level. We also uncover evidence that suggests that the mechanism behind this result is that in some cases houses were not fixed (i.e., owners having pocketed the payments) - indeed, insurance claims that were actively repaired (rather than paid directly) did not lead to any relative deterioration in prices. We use a genetic machine-learning algorithm which aims to improve on a standard hedonic model, and identify the dynamics of the housing market in the city, and three data sets: All housing market transactions, all earthquake insurance claims submitted to the public insurer, and all of the local authority’s building-consents data. Our results are important not only because the utility of catastrophe insurance is often questioned, but also because understanding what happens to property markets after disasters should be part of the overall assessment of the impact of the disaster itself. Without a quantification of these impacts, it is difficult to design policies that will optimally try to prevent or ameliorate disaster impacts.

New Zealand’s unreinforced Masonry Buildings: Facing up to the earthquake.

The damage caused by the 2011 Christchurch earthquake has led to the introduction of compulsory seismic strengthening legislation for all unreinforced earthquake-prone masonry buildings (URM) within New Zealand. The legislation, passed in 2013, requires all such URM commercial, multi-unit and multi-storey residential buildings to be upgraded and strengthened to a minimum of 34% or more of the New Building Standard, irrespective of the earthquake zone within which they are located. Buildings so designated and in high earthquake zones will have a very limited time bring their buildings into line with these requirements. The proposal particularly affects old URM buildings. Some of these are buildings have a declared heritage value, many do not. Most were built around the turn of the twentieth Century. Together they make up a considerable portion of many small town commercial precincts. The legislation affects all parts of New Zealand, regardless of the particular region’s exposure to earthquake risk.The paper will background the current legislation, compare international legislation and study the financial effects of the legislation, case studying buildings within two distinct seismic zones. The findings suggest that where the cost of the upgrade puts the viability of the building as a rental investment at risk, the owner will most likely adopt demolition is the only feasible outcome. This could have far-reaching implications for the wellbeing of many small towns within New Zealand. An alternative strategy is examined and assessed.

Seismic performance of helical piles in dry sand from large-scale shaking table tests

Recent earthquakes have highlighted the need for safe and efficient construction of earthquake-resilient structures. Meanwhile, helical piles are gaining popularity as a foundation not only for new construction, but also retrofitted structures, owing to their advantages over conventional driven pile alternatives. In addition, several structures supported by helical piles in New Zealand sustained minimal damage during the Christchurch earthquake, proving that helical piles can be a suitable foundation option in highly seismic areas. However, there is a knowledge gap concerning their seismic performance. Therefore, the current study investigates the performance of helical piles through a full-scale shaking table test programme – the inaugural large-scale seismic testing programme performed on helical piles. The experimental set-up involved installing ten steel piles with different configurations and pile head masses in dry sand enclosed in a laminar shear box mounted on the Network for Earthquake Engineering Simulation at University of California, San Diego (NEES/UCSD) large high-performance outdoor shaking table (LHPOST). The loading scheme consisted of white noise and two earthquake time histories with varying intensity and frequency content. The experimental results are presented in terms of the natural frequency and response of test piles (peak deflections). The effects of loading frequency and intensity and the pile's geometrical configuration and installation method were evaluated.

Governing Through Relationship: A Positive Critique of School Social Work Practice in Post-Earthquake, Christchurch, New Zealand

AbstractThis article outlines some findings from an inquiry undertaken in the aftermath of 2011 earthquake in Christchurch, New Zealand, in which positive critique was used to examine the practice accounts of twelve school social workers alongside characteristics of recovery policies. Consistent with Foucault’s (1988, 2003a,b, 2013a) mode of critique and his theorisation of biopolitics and pastoral power, positive critique recognises the multiplicity and productivity of contemporary power relations operating at the populational, collective and individual levels of life. A feature of the participants’ accounts of their practices with affected schoolchildren in the recovery space is their commitment to restoring and protecting their clients’ well-being through therapeutically inclined relational practice. The Christchurch earthquake recovery strategy also sets out the provision of specialised, individual assistance for vulnerable populations excluded from ‘normal’ psychosocial recovery processes because of their inability to participate in community self-help initiatives. The findings presented in this article provide a critical space for social workers to reflect on the dimensions of their relational work that function as therapeutic governance practices that can both strengthen and resist the normative notions of vulnerability and recovering well.

Building Organisational Resilience for the Construction Industy: Strategic Resilience Indicators

New Zealand has been affected by a number of natural disasters in recent years. One such example is the 2010 Christchurch earthquake that led to significant impacts to businesses, buildings and critical infrastructure. Construction organisations play an important role in reconstruction programs, and communities rely on their services, particularly post-disaster. Improving the resilience of construction organisations to natural disasters not only minimises the negative consequences to their organisations post-disaster and enhances their organisational performance during business as usual, but also helps to improve community resilience. However, very few studies have developed the concept of organizational resilience and none specifically in the construction sector. This paper identifies strategic resilience indicators for construction organizations. Triangulation analysis of the five studies, in-depth interviews and questionnaire surveys revealed leading indicators of organizational resilience which can help to develop a resilience framework for construction organizations. The findings suggest that the construction industry needs a framework that fosters resilience which itself can potentially enhance organisational capacity to recover quickly after a crisis or disaster.

Trophic Indicators of Ecological Resilience in a Tidal Lagoon Estuary Following Wastewater Diversion and Earthquake Disturbance

Estuary ecological resilience can be gauged by response of estuary trophic state to abatement of nutrient pollution. Changes in trophic indicators were studied in the Avon-Heathcote Estuary (AHE) in Christchurch, New Zealand, over 6 years, spanning diversion of city wastewater inputs to an offshore outfall in 2010, and to temporary enrichment caused by the 2011 Christchurch earthquake. It was hypothesised that the tidally well-flushed and sandy AHE would not harbour a ‘legacy’ of eutrophication and would rapidly gain improved ecological function following the diversion. AHE sediments were coarse (156 μm median grain size) with low organic matter (OM 1.2%, N 0.03%, C 0.3%), which changed little either with diversion or earthquake. Upon diversion, median water column and porewater ammonium (36, 185 μmol) decreased by 87% and 57%, respectively, benthic microalgae (269 mg chlorophyll-a m−2) fell by 58%, and enrichment-affiliated polychaetes (3700–8000 m−2) fell by 60–80% at sites with largest benthic microalgal reductions, all within < 1–2 years. Oxygen and ammonium fluxes were usually oligotrophic and changed little upon diversion, except near the historic wastewater discharge site. Denitrification became more important for N loss, increasing from 5 to 29% of estuary N load. Responses to earthquake-driven enrichment were transient. Despite decades of heavy N loading and eutrophic growths of benthic microalgae and macroalgae, the AHE did not store a eutrophic legacy in its sediments. It reacted rapidly to improved water quality allowed by the outfall, showing that this common estuary type (sandy, well-flushed tidal lagoon) was resilient to eutrophication upon stressor removal.

Evaluating natural experiments to measure the co-benefits of urban policy interventions to reduce carbon emissions in New Zealand

Finding effective policy interventions for addressing the Sustainable Development Goals, such as reducing carbon emissions (SDG 13), which can also enhance good health and wellbeing (SDG 3), is urgent. Many promising interactions occur between sustainable cities and communities (SDG 11), clean water and sanitation (SDG 6) and affordable and clean energy (SDG 7), which sit at the centre of integrated urban planning and regeneration. In this paper, we consider the framing and findings of four policies we have evaluated as natural experiments, all of which have important co-benefits, which were not always the focus of the initial policies. These policies are: the installation of cycleways and walkways in existing suburbs; a central government measure to recentralise employment after the 2011 Christchurch earthquakes; the streamlining of housing developments by reducing land-use regulation; and ongoing changes of policy about public housing investment. We show that having a clear understanding of the benefits of increased physical activity for health, for example, could accelerate the reduction of carbon emissions. Also, decisions about infrastructure, housing and job locations can generate health and environmental gains if supported by broader public transport investments. Cycling and walking are also more likely to substitute for short habitual car trips. Similarly, measuring the co-benefits of differential residential models, relating to land-use and renewable energy, provides a framework that can facilitate learning from policy interventions, enabling wider and potentially more rapid generalisation of policies, including those for climate change mitigation.

Effects of induced anisotropy on multiple liquefaction properties of sand with initial static shear

The multiple liquefaction phenomenon has been attracting the attention of more and more researchers and engineers since the 2010–2011 Christchurch Earthquakes and the 2011 Great East Japan Earthquake. However, little has been known about the multiple liquefaction properties of sloped grounds. In this study, therefore, multiple liquefaction tests that consider the initial static shear stress, which have never been conducted before, were carried out with a special designed apparatus, the stacked-ring shear apparatus. A series of multiple liquefaction tests revealed that induced anisotropy, which is weak against the loading opposite to the direction of the initial static shear stress, was produced by the liquefaction of a sloped ground. As a result, a significant decrease in the liquefaction resistance during the next cyclic of shearing occurred. The indicators which influenced the magnitude of anisotropy were also discussed from the perspective of the reconsolidation procedures, the magnitude of initial static shear stress, and the type of ending of the previous liquefaction stage. In addition, it turned out that in the multiple liquefaction test with a larger initial static shear stress, the re-liquefaction resistance was higher because the shear stress opposite to the direction of the initial static shear stress, causing large negative dilatancy due to anisotropy, was smaller in that test.

Modeling post-earthquake business recovery time: An analytical framework

This study develops an analytical framework for modeling business recovery times after seismic events. These recovery times are important to understand, as business interruption (BI) is a significant factor in the survival of businesses and communities after disasters, and can cause a large proportion of the losses in such events. To date however, few post-earthquake recovery studies specifically account for business recovery time. The proposed framework considers multiple types of earthquake-induced downtime that may impact business recovery, such as building recovery and disruption to the wider community, as well as tactics employed by businesses to mitigate these times. The framework's potential to provide insight on business recovery is evaluated using observed recovery time data for 22 businesses affected by the 2011 Mw 6.1 Christchurch earthquake in New Zealand. It is found that recovery times calculated according to the framework align significantly better with observed business recovery times compared to calculated downtimes of businesses' pre-earthquake physical locations, which are often used as proxies for business recovery. These findings highlight the importance of accounting for multiple factors when modeling business recovery due to seismic events.

The Christchurch earthquake: lessons from the real-life experiences of early childhood teachers

ABSTRACT ven though natural disasters are becoming increasingly prevalent, research investigating and offering practical advice to teachers around caring for children during and after an earthquake event is limited. This article aims to provide unique insight from early childhood teachers into a real-life experience of caring for children at their early childhood center during and after the earthquake in Christchurch New Zealand in February 2011. Details of the setting on the day of the earthquake prior to the event are discussed, followed by what happened during the earthquake, the situation immediately following the earthquake when parents arrived to collect their children, and the subsequent days and weeks following the earthquake. The article concludes with advice and guidance from the teachers around tips and strategies for supporting children’s social and emotional wellbeing in such a situation for fellow teachers who may find themselves in similar circumstances in the future. Through providing this discussion, future early childhood teachers can be guided, not by hypothetical best practice, but by real-life events from early childhood teachers who have first-hand experience of supporting children prior to, during and after an earthquake event. This therefore provides essential opportunities for learning from practice and preparing for the future.

Assessing the residual capacity and future performance of the Mason River Bridge, NZ

On 14 November 2016, the Mason River Bridge in North Canterbury, New Zealand, was rocked by one of the most complex and violent earthquakes ever recorded. This resulted in significant plastic hinging at the base of the pier columns. To avoid major costly repairs and strengthening, an innovative hardness and material testing technique was employed to determine the damage to reinforcement and residual capacity of the plastic hinges. This technique was developed for damaged buildings following the 2010 and 2011 Christchurch earthquakes, and is the first known example of its use for an earthquake-damaged bridge. Coupled with detailed non-linear time history analysis of the structure, this testing and analysis allowed the bridge's current and future seismic performance to be determined and helped justify the use of more conventional repairs, with major strengthening and seismic retrofit being avoided. This paper discusses the earthquake damage observed, the seismic performance of the structure, the advantages and disadvantages of the innovative material testing techniques, maintenance and repairs to the bridge and the expected performance of the repaired columns

A Decision-Support Algorithm for Post-Earthquake Water Services Recovery and Its Application to the 22 February 2011 Mw6.2 Christchurch Earthquake

As the cost of lifeline disruption rises with the size and complexity of urban communities, increasing efforts are put into enhancing infrastructure resilience to natural disasters. Aiming to improve the understanding of water supply network seismic resilience, this paper examines in detail the initial performance and restoration of the water supply network following the 22 February 2011 Mw6.2 Christchurch, New Zealand earthquake. In addition, a method to optimize the recovery of such systems is developed in two phases: the prioritization of pipe inspection and prioritization of pipe repairs. The results inferred from the observed pipe repairs suggest that the recovery was carried out efficiently; however, applying the proposed methodology would have substantially improved the recovery of the system with a 30% reduction in the number of buildings deprived of water in the first two days. Assumptions and limitations of the modeling are also discussed and practical solutions given to apply this framework in real-time for post-earthquake restoration.

Segmented pipeline damage predictions using liquefaction vulnerability parameters

Past observations showed that pipeline damages in liquefaction zones are significantly higher than the damages in areas where there was no liquefaction. Existing vulnerability relationships for the pipelines in liquefaction zones utilize parameters such as ground displacement, horizontal ground strain, angular distortion or both. These relationships are particularly useful in performance or risk assessment of pipeline systems. However, prediction of these parameters for pipeline damage estimates is difficult to perform and highly variable with current procedures. This paper proposes new correlations of asbestos cement (AC), cast iron (CI) and polyvinyl chloride (PVC) pipeline damage, expressed as repairs/km, with three different liquefaction parameters: liquefaction severity number (LSN), one-dimensional volumetric reconsolidation settlement (SV1D), and liquefaction potential index (LPI). The pipeline damage data from 22 February 2011, Mw = 6.2 Christchurch earthquake and geotechnical information pertaining to liquefied area in Christchurch are utilized herein. Cone penetration test (CPT) based Boulanger and Idriss [1] liquefaction triggering procedure with 15th, 50th and 85th percentile cyclic resistance ratio (CRR) curves (corresponding to probabilities of liquefaction, PL, equal to 15%, 50%, and 85%) was used to calculate the parameters. It is shown that the relationships between AC, CI and PVC pipeline damages and LSN, SV1D and LPI are strong, except for the correlation for AC pipeline damage versus LPI. Considering CI and PVC pipelines, both LSN and LPI correlations are comparable and slightly better than SV1D correlations. Use of different probabilities of liquefaction triggering does not have significant effect on correlations with LSN and SV1D whereas the same is not true for LPI correlations. Regarding the resilience of pipelines, PVC and AC pipelines performed the best and worst, respectively in all cases with CI pipelines in the middle. The correlations have the potential for use with existing or new liquefaction hazard maps for prediction of pipeline damage from future earthquakes.

Gun Violence and Cardiovascular Health.

Gun Violence and Cardiovascular Health.

Two major earthquakes in Christchurch were not associated with increased ventricular arrhythmias: Analysis of implanted defibrillator diagnostics.

AimChristchurch, New Zealand, experienced two major earthquakes on 4th September 2010 and 22nd February 2011. Previous studies have demonstrated that earthquakes are associated with sudden cardiac deaths. Whilst myocardial ischemia would contribute to this, ventricular arrhythmia triggered by stress has also been suggested. We aim to study the impact of the two earthquakes on ventricular arrhythmia events.MethodsWe conducted a retrospective review of all patients resident in the earthquake zone with implantable defibrillators. Ventricular arrhythmia requiring therapy and non-sustained events were recorded from the period of 30 days before thru 30 days after the two earthquakes. Weekly event rates were calculated and compared using log rank analysis. Results are expressed as mean (range), significance was determined at the <0.05 level.ResultsFor the 211 patients who were exposed to the 2010 earthquake, there was no difference in the proportion of patients free of therapy, either Shock or ATP (0.943 before and 0.933 after the earthquake, p = 0.85, ns). Similarly, there was no significant increase in events requiring therapy in the 236 patients exposed to the 2011 earthquake (0.957 before and 0.961 after the earthquake, p = 0.80, ns). We identified one patient who required multiple therapy for ventricular tachycardia immediately following both earthquakes.ConclusionThe two Christchurch earthquakes were not associated with an increase in the event rate of either sustained or non-sustained ventricular arrhythmias in our patients. We identified only a single patient who had arrhythmic storms immediately following the earthquakes.