A significant portion of economic loss from the Canterbury Earthquake sequence in 2010-2011 was attributed to losses to residential buildings. These accounted for approximately $12B of a total $40B economic losses (Horspool, 2016). While a significant amount of research effort has since been aimed at research in the commercial sector, little has been done to reduce the vulnerability of the residential building stock.
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.
This research investigates the validation of simulated ground motions on complex structural systems. In this study, the seismic responses of two buildings are compared when they are subjected to as-recorded ground motions and simulated ones. The buildings have been designed based on New Zealand codes and physically constructed in Christchurch, New Zealand. The recorded ground motions are selected from 40 stations database of the historical 22 Feb. 2011 Christchurch earthquake. The Graves and Pitarka (2015) methodology is used to generate the simulated ground motions. The geometric mean of maximum inter-story drift and peak floor acceleration are selected as the main seismic responses. Also, the variation of these parameters due to record to record variability are investigated. Moreover, statistical hypothesis testing is used to investigate the similarity of results between observed and simulated ground motions. The results indicate a general agreement between the peak floor acceleration calculated by simulated and recorded ground motions for two buildings. While according to the hypothesis tests result, the difference in drift can be significant for the building with a shorter period. The results will help engineers and researchers to use or revise the procedure by using simulated ground motions for obtaining seismic responses.
After the Christchurch earthquakes, the government declared about 8000 houses as Red Zoned, prohibiting further developments in these properties, and offering the owners to buy them out. The government provided two options for owners: the first was full payment for both land and dwelling at the 2007 property evaluation, the second was payment for land, and the rest to be paid by the owner’s insurance. Most people chose the second option. Using data from LINZ combined with data from StatNZ, this project empirically investigates what led people to choose this second option, and what were the implications of these choices for the owners’ wealth and income.
We measure the longer-term effect of a major earthquake on the local economy, using night-time light intensity measured from space, and investigate whether insurance claim payments for damaged residential property affected the local recovery process. We focus on the destructive Canterbury Earthquake Sequence (CES) 2010 -2011 as our case study. Uniquely for this event, more than 95% of residential housing units were covered by insurance, but insurance payments were staggered over 5 years, enabling us to identify their local impact. We find that night-time luminosity can capture the process of recovery and describe the recovery’s determinants. We also find that insurance payments contributed significantly to the process of economic recovery after the earthquake, but delayed payments were less affective and cash settlement of claims were more effective than insurance-managed repairs in contributing to local recovery.
Geospatial liquefaction models aim to predict liquefaction using data that is free and readily-available. This data includes (i) common ground-motion intensity measures; and (ii) geospatial parameters (e.g., among many, distance to rivers, distance to coast, and Vs30 estimated from topography) which are used to infer characteristics of the subsurface without in-situ testing. Since their recent inception, such models have been used to predict geohazard impacts throughout New Zealand (e.g., in conjunction with regional ground-motion simulations). While past studies have demonstrated that geospatial liquefaction-models show great promise, the resolution and accuracy of the geospatial data underlying these models is notably poor. As an example, mapped rivers and coastlines often plot hundreds of meters from their actual locations. This stems from the fact that geospatial models aim to rapidly predict liquefaction anywhere in the world and thus utilize the lowest common denominator of available geospatial data, even though higher quality data is often available (e.g., in New Zealand). Accordingly, this study investigates whether the performance of geospatial models can be improved using higher-quality input data. This analysis is performed using (i) 15,101 liquefaction case studies compiled from the 2010-2016 Canterbury Earthquakes; and (ii) geospatial data readily available in New Zealand. In particular, we utilize alternative, higher-quality data to estimate: locations of rivers and streams; location of coastline; depth to ground water; Vs30; and PGV. Most notably, a region-specific Vs30 model improves performance (Figs. 3-4), while other data variants generally have little-to-no effect, even when the “standard” and “high-quality” values differ significantly (Fig. 2). This finding is consistent with the greater sensitivity of geospatial models to Vs30, relative to any other input (Fig. 5), and has implications for modeling in locales worldwide where high quality geospatial data is available.
Earthquake-triggered soil liquefaction caused extensive damage and heavy economic losses in Christchurch during the 2010-2011 Canterbury earthquakes. The most severe manifestations of liquefaction were associated with the presence of natural deposits of clean sands and silty sands of fluvial origin. However, liquefaction resistance of fines-containing sands is commonly inferred from empirical relationships based on clean sands (i.e. sands with less than 5% fines). Hence, existing evaluation methods have poor accuracy when applied to silty sands. Also, existing methods do not quantify appropriately the influence on liquefaction resistance of soil fabric and structure, which are unique to a specific depositional environment. This study looks at the influence of fines content, soil fabric (i.e. arrangement of soil particles) and structure (e.g. layering, segregation) on the undrained cyclic behaviour and liquefaction resistance of fines-containing sandy soils from Christchurch using Direct Simple Shear (DSS) tests on soil specimens reconstituted in the laboratory with the water sedimentation technique. The poster describes experimental procedures and presents early test results on two sands retrieved at two different sites in Christchurch.
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).
Introduction This poster presents the inferred initial performance and recovery of the water supply network of Christchurch following the 22 February 2011 Mw 6.2 earthquake. Results are presented in a geospatial and temporal fashion. This work strengthens the current understanding of the restoration of such a system after a disaster and quantifies the losses caused by this earthquake in respect with the Christchurch community. Figure 1 presents the topology of the water supply network as well as the spatial distribution of the buildings and their use.
Hybrid broadband simulation methods typically compute high-frequency portion of ground-motions using a simplified-physics approach (commonly known as “stochastic method”) using the same 1D velocity profile, anelastic attenuation profile and site-attenuation (κ0) value for all sites. However, these parameters relating to Earth structure are known to vary spatially. In this study we modify this conventional approach for high-frequency ground-shaking by using site-specific input parameters (referred to as “site-specific”) and analyze improvements over using same parameters for all sites (referred to as “generic”). First, we theoretically understand how different 1D velocity profiles, anelastic attenuation profiles and site-attenuation (κ0) values affects the Fourier Acceleration Spectrum (FAS). Then, we apply site-specific method to simulate 10 events from the 2010-2011 Canterbury earthquake sequence to assess performance against the generic approach in predicting recorded ground-motions. Our initial results suggest that the site-specific method yields a lower simulation standard deviation than generic case.
© 2018 Springer Nature B.V. This study compares seismic losses considering initial construction costs and direct-repair costs for New Zealand steel moment-resisting frame buildings with friction connections and those with extended bolted-end-plate connections. A total of 12 buildings have been designed and analysed considering both connection types, two building heights (4-storey and 12-storey), and three locations around New Zealand (Auckland, Christchurch, and Wellington). It was found that buildings with friction connections required design to a higher design ductility, yet are generally stiffer due to larger beams being required to satisfy higher connection overstrength requirements. This resulted in the frames with friction connections experiencing lower interstorey drifts on most floors but similar peak total floor accelerations, and subsequently incurring lower drift-related seismic repair losses. Frames with friction connections tended to have lower expected net-present-costs within 50 years of the building being in service for shorter buildings and/or if located in regions of high seismicity. None of the frames with friction connections in Auckland showed any benefits due to the low seismicity of the region.
Background: Earthquakes are found to have lingering post-disaster effects on children that can be present for months or years after the disaster, including hyperarousal symptoms. Young children have the most difficulties in regulating their emotions, especially when they are highly aroused. Colouring-in mandala designs have been found to reduce hyperarousal symptoms of stress in young adults. The purpose of this study was to determine if the same effects of colouring-in mandalas would be seen with children showing signs of hyperarousal. Research Question: To identify what effect colouring-in mandala designs would have on the heart rate in a young child showing signs of hyperarousal. Method: Following approved procedures for informed consent, two 6-year-old girls from a Christchurch primary school were chosen for the study. Heart rate was measured using a Fitbit in a single subject design. The baseline, colouring-in and a second baseline phase were conducted during mathematics. The participants and their teacher reported on arousal, enjoyment, and positive and problem behaviours. The study took 26 school days to complete. Results: Compared with baseline, the average heart rate data showed no decrease in heart rate (i.e., calming effect) during the mandala colouring-in task phase. Conclusions: The participants enjoyed colouring-in the mandalas, but the average heart rate data did not show that colouring-in pre-drawn designs reduced heart rate, a measure of arousal. Major study limitations included; not having suitable participants or a suitable setting for the colouring-in task, and not being able to observe both participants.
Very little research exists on total house seismic performance. This testing programme provides stiffness and response data for five houses of varying ages including contributions of non-structural elements. These light timber framed houses in Christchurch, New Zealand had minor earthquake damage from the 2011 earthquakes and were lateral load tested on site to determine their strength and stiffness, and preliminary damage thresholds. Dynamic characteristics were also investigated. Various loading schemes were utilised including quasi-static loading above the foundation, unidirectional loading through the floor diaphragm, cyclic quasi-static loading and snapback tests. Dynamic analysis on two houses provided the seismic safety levels of post-quake houses with respect to local hazard levels. Compared with New Zealand Building Standards all the tested houses had an excess of strength, damage is a significant consideration in earthquake resilience and was observed in all of the houses. A full size house laboratory test is proposed.
Farming and urban regions are impacted by earthquake disasters in different ways, and feature a range of often different recovery requirements. In New Zealand, and elsewhere, most earthquake impact and recovery research is urban focused. This creates a research deficit that can lead to the application of well-researched urban recovery strategies in rural areas to suboptimal effect. To begin to reduce this deficit, in-depth case studies of the earthquake impacts and recovery of three New Zealand farms severely impacted by the 14th November 2016, M7.8 Hurunui-Kaikōura earthquake were conducted. The initial earthquake, its aftershocks and coseismic hazards (e.g., landslides, liquefaction, surface rupture) affected much of North Canterbury, Marlborough and the Wellington area. The three case study farms were chosen to broadly represent the main types of farming and topography in the Hurunui District in North Canterbury. The farms were directly and indirectly impacted by earthquakes and related hazards. On-farm infrastructure (e.g., woolsheds, homesteads) and essential services (e.g., water, power), frequently sourced from distributed networks, were severely impacted. The earthquake occurred after two years of regional drought had already stressed farm systems and farmers to restructuring or breaking point. Cascading interlinked hazards stemming from the earthquakes and coseismic hazards continued to disrupt earthquake recovery over a year after the initial earthquake. Semi-structured interviews with the farmers were conducted nine and fourteen months after the initial earthquake to capture the timeline of on-going impacts and recovery. Analysis of both geological hazard data and interview data resulted in the identification of key factors influencing farm level earthquake impact and recovery. These include pre-existing conditions (e.g., drought); farm-specific variations in recovery timelines; and resilience strategies for farm recovery resources. The earthquake recovery process presented all three farms with opportunities to change their business plans and adapt to mitigate on-going and future risk.
Detailed studies on the sediment budget may reveal valuable insights into the successive build-up of the Canterbury Plains and their modification by Holocene fluvialaction connected to major braided rivers. Additionally, they bear implications beyond these fluvial aspects. Palaeoseismological studies claim to have detected signals of major Alpine Fault earthquakes in coastal environments along the eastern seaboard of the South Island (McFadgen and Goff, 2005). This requires high connectivity between the lower reaches of major braided rivers and their mountain catchments to generate immediate significant sediment pulses. It would be contradictory to the above mentioned hypothesis though. Obtaining better control on sediment budgets of braided rivers like the Waimakariri River will finally add significant value to multiple scientific and applied topics like regional resource management. An essential first step of sediment budget studies Is to systematically map the geomorphology, conventionally in the field and/or using remote-sensing applications, to localise, genetically identify, and classify landforms or entire toposequences of the area being investigated. In formerly glaciated mountain environments it is also indispensable to obtain all available chronological information supporting subsequent investigations.
On November 14 2016 a magnitude 7.8 earthquake struck the south island of New Zealand. The earthquake lasted for just two minutes with severe seismic shaking and damage in the Hurunui and Kaikōura districts. Although these are predominantly rural areas, with scattered small towns and mountainous topography, they also contain road and rail routes that are essential parts of the national transport infrastructure. This earthquake and the subsequent recovery are of particular significance as they represent a disaster following in close proximity to another similar disaster, with the Canterbury earthquakes occurring in a neighboring district five years earlier. The research used an inductive qualitative case study to explore the nature of the Kaikōura recovery. That recovery process involved a complex interplay between the three parties; (a) the existing local government in the district, (b) central government agencies funding the recovery of the local residents and the national transport infrastructure, and (c) recovery leaders arriving with recent expertise from the earlier Canterbury disaster. It was evident that three groups: locals, government, and experts represented a multi-party governance debate in which the control of the Kaikōura earthquake recovery was shared amongst them. Each party had their own expertise, adgenda and networks that they brought to the Kaikōura recovery, but this created tensions between external expertise and local, community leadership. Recent earthquake research suggests that New Zealand is currently in the midst of an earthquake cluster, with further seismic disasters likely to occur in relatively close succession. This is likely to be compounded by the increasing frequency of other natural disasters with the effects of climate change. The present study investigates a phenomenon that may become increasingly common, with the transfer of disaster expertise from one event to another, and the interface between those experts with local and national government in directing recoveries. The findings of this study have implications for practitioners and policy makers in NZ and other countries where disasters are experienced in close spatial and temporal proximity.
For 150,000 Christchurch school students, the 12.51 pm earthquake of 22 February 2011 shattered their normal lunch time activities and thrust their teachers into the role of emergency first responders. Whether helping students (children) escape immediate danger, or identifying and managing the best strategies for keeping children safe, including provision of extended caregiving when parents were unable to return to school to retrieve their children, teachers had to manage their own fears and trauma reactions in order to appear calm and prevent further distress for the children in their care. Only then did teachers return to their families. Eighteen months later, twenty teachers from across Christchurch, were interviewed. At 12.51pm, the teachers were essentially first responders. Using their usual methods for presenting a calm and professional image, the teachers’ emotion regulation (ER) strategies for managing their immediate fears were similar to those of professional first responders, with similar potential for subsequent burnout and negative emotional effects. Teachers’ higher emotional exhaustion and burnout 18 months later, were associated with school relocation. Lower burnout was associated with more emotional awareness, ER and perceived support. Consistent with international research, teachers’ use of cognitive reappraisal (re-thinking a situation) was an effective ER strategy, but this may not prevent teachers’ emotional resources from eventually becoming depleted. Teachers fulfill an important role in supporting children’s psychosocial adjustment following a natural disaster. However, as also acknowledged in international research, we need to also focus on supporting the teachers themselves.
The nonlinear dynamic soil-foundation-structure interaction (SFSI) can signifi cantly affect the seismic response of buildings, causing additional deformation modes, damage and repair costs. Because of nonlinear foundation behaviour and interactions, the seismic demand on the superstructure may considerably change, and also permanent deformations at the foundation level may occur. Although SFSI effects may be benefi cial to the superstructure performance, any advantage would be of little structural value unless the phenomenon can be reliably controlled and exploited. Detrimental SFSI effects may also occur, including acceleration and displacement response ampli cation and differential settlements, which would be unconservative to neglect. The lack of proper understanding of the phenomenon and the limited available simpli ed tools accounting for SFSI have been major obstacles to the implementation of integrated design and assessment procedures into the everyday practice. In this study concepts, ideas and practical tools (inelastic spectra) for the seismic design and assessment of integrated foundation-superstructure systems are presented, with the aim to explicitly consider the impact of nonlinearities occurring at the soil-foundation interface on the building response within an integrated approach, where the foundation soil and superstructure are considered as part of an integrated system when evaluating the seismic response, working synergically for the achievement of a target global performance. A conceptual performance-based framework for the seismic design and assessment of integrated foundation-superstructure systems is developed. The framework is based on the use of peak and residual response parameters for both the superstructure and the foundation, which are then combined to produce the system performance matrix. Each performance matrix allows for worsening of the performance when different contributions are combined. An attempt is made to test the framework by using case histories from the 2011 Christchurch earthquake, which are previously shown to have been severely affected by nonlinear SFSI. The application highlights the framework sensitivity to the adopted performance limit states, which must be realistic for a reliable evaluation of the system performance. Constant ductility and constant strength inelastic spectra are generated for nonlinear SFSI systems (SDOF nonlinear superstructure and 3DOF foundation allowing for uplift and soil yielding), representing multistorey RC buildings with shallow rigid foundations supported by cohesive soils. Different ductilities/strengths, hysteretic rules (Bi-linear, Takeda and Flag-Shape), soil stiffness and strength and bearing capacity factors are considered. Footings and raft foundations are investigated, characterized respectively by constant (3 and 8) and typically large bearing capacity factors. It is confi rmed that when SFSI is considered, the superstructure yielding force needed to satisfy a target ductility for a new building changes, and that similarly, for an existing building, the ductility demand on a building of a given strength varies. The extent of change of seismic response with respect to xed-base (FB) conditions depends on the class of soils considered, and on the bearing capacity factor (SF). For SF equal to 3, the stiffer soils enhance the nonlinear rotational foundation behaviour and are associated with reduced settlement, while the softer ones are associated with increased settlement response but not signi ficant rotational behaviour. On average terms, for the simplifi ed models considered, SFSI is found to be bene cial to the superstructure performance in terms of acceleration and superstructure displacement demand, although exceptions are recorded due to ground motion variability. Conversely, in terms of total displacement, a signi cant response increase is observed. The larger the bearing capacity factor, the more the SFSI response approaches the FB system. For raft foundation buildings, characterized by large bearing capacity factors, the impact of foundation response is mostly elastic, and the system on average approaches FB conditions. Well de fined displacement participation factors to the peak total lateral displacement are observed for the different contributions (i.e. peak foundation rotation and translation and superstructure displacement). While the superstructure and foundation rotation show compensating trends, the foundation translation contribution varies as a function of the moment-to-shear ratio, becoming negligible in the medium-to-long periods. The longer the superstructure FB period, the less the foundation response is signifi cant. The larger the excitation level and the less ductile the superstructure, the larger the foundation contribution to the total lateral displacement, and the less the superstructure contribution. In terms of hysteretic behaviour, its impact is larger when the superstructure response is more signifi cant, i.e. for the softer/weaker soils and larger ductilities. Particularly, for the Flag Shape rule, larger superstructure displacement participation factors and smaller foundation contributions are recorded. In terms of residual displacements, the total residual-to-maximum ratios are similar in amplitudes and trends to the corresponding FB system responses, with the foundation and superstructure contributions showing complementary trends. The impact of nonlinear SFSI is especially important for the Flag Shape hysteresis rule, which would not otherwise suffer of any permanent deformations. By using the generated peak and residual inelastic spectra (i.e. inelastic acceleration/ displacement modifi cation factor spectra, and/or participation factor and residual spectra), conceptual simplifi ed procedures for the seismic design and assessment of integrated foundation-superstructure systems are presented. The residual displacements at both the superstructure and foundation levels are explicitly considered. Both the force- and displacement-based approaches are explored. The procedures are de fined to be complementary to the previously proposed integrated performance-based framework. The use of participation factor spectra allows the designer to easily visualize the response of the system components, and could assist the decision making process of both the design and assessment of SFSI systems. The presented numerical results have been obtained using simpli ed models, assuming rigid foundation behaviour and neglecting P-Delta effects. The consideration of more complex systems including asymmetry in stiffness, mass, axial load and ground conditions with a exible foundation layout would highlight detrimental SFSI effects as related to induced differential settlements, while accounting for PDelta effects would further amplify the displacement response. Also, the adopted acceleration records were selected and scaled to match conventional design spectra, thus not representing any response ampli cation in the medium-to-long period range which could as well cause detrimental SFSI effects. While these limitations should be the subject of further research, this study makes a step forward to the understanding of SFSI phenomenon and its incorporation into performance-based design/assessment considerations.
One of the most controversial issues highlighted by the 2010-2011 Christchurch earthquake series and more recently the 2016 Kaikoura earthquake, has been the evident difficulty and lack of knowledge and guidelines for: a) evaluation of the residual capacity damaged buildings to sustain future aftershocks; b) selection and implementation of a series of reliable repairing techniques to bring back the structure to a condition substantially the same as prior to the earthquake; and c) predicting the cost (or cost-effectiveness) of such repair intervention, when compared to fully replacement costs while accounting for potential aftershocks in the near future. As a result of such complexity and uncertainty (i.e., risk), in combination with the possibility (unique in New Zealand when compared to most of the seismic-prone countries) to rely on financial support from the insurance companies, many modern buildings, in a number exceeding typical expectations from past experiences at an international level, have ended up being demolished. This has resulted in additional time and indirect losses prior to the full reconstruction, as well as in an increase in uncertainty on the actual relocation of the investment. This research project provides the main end-users and stakeholders (practitioner engineers, owners, local and government authorities, insurers, and regulatory agencies) with comprehensive evidence-based information to assess the residual capacity of damage reinforced concrete buildings, and to evaluate the feasibility of repairing techniques, in order to support their delicate decision-making process of repair vs. demolition or replacement. Literature review on effectiveness of epoxy injection repairs, as well as experimental tests on full-scale beam-column joints shows that repaired specimens have a reduced initial stiffness compared with the undamaged specimen, with no apparent strength reduction, sometimes exhibiting higher displacement ductility capacities. Although the bond between the steel and concrete is only partially restored, it still allows the repaired specimen to dissipate at least the same amount of hysteretic energy. Experimental tests on buildings subjected to earthquake loading demonstrate that even for severe damage levels, the ability of the epoxy injection to restore the initial stiffness of the structure is significant. Literature review on damage assessment and repair guidelines suggests that there is consensus within the international community that concrete elements with cracks less than 0.2 mm wide only require cosmetic repairs; epoxy injection repairs of cracks less and 2.0 mm wide and concrete patching of spalled cover concrete (i.e., minor to moderate damage) is an appropiate repair strategy; and for severe damaged components (e.g., cracks greater than 2.0 mm wide, crushing of the concrete core, buckling of the longitudinal reinforcement) local replacement of steel and/or concrete in addition to epoxy crack injection is more appropriate. In terms of expected cracking patterns, non-linear finite element investigations on well-designed reinforced concrete beam-to-column joints, have shown that lower number of cracks but with wider openings are expected to occur for larger compressive concrete strength, f’c, and lower reinforcement content, ρs. It was also observed that the tensile concrete strength, ft, strongly affects the expected cracking pattern in the beam-column joints, the latter being more uniformly distributed for lower ft values. Strain rate effects do not seem to play an important role on the cracking pattern. However, small variations in the cracking pattern were observed for low reinforcement content as it approaches to the minimum required as per NZS 3101:2006. Simple equations are proposed in this research project to relate the maximum and residual crack widths with the steel strain at peak displacement, with or without axial load. A literature review on fracture of reinforcing steel due to low-cycle fatigue, including recent research using steel manufactured per New Zealand standards is also presented. Experimental results describing the influence of the cyclic effect on the ultimate strain capacity of the steel are also discussed, and preliminary equations to account for that effect are proposed. A literature review on the current practice to assess the seismic residual capacity of structures is also presented. The various factors affecting the residual fatigue life at a component level (i.e., plastic hinge) of well-designed reinforced concrete frames are discussed, and equations to quantify each of them are proposed, as well as a methodology to incorporate them into a full displacement-based procedure for pre-earthquake and post-earthquake seismic assessment.
Land cover change information in urban areas supports decision makers in dealing with public policy planning and resource management. Remote sensing has been demonstrated as an efficient and accurate way to monitor land cover change over large extents. The Canterbury Earthquake Sequence (CES) caused massive damage in Christchurch, New Zealand and resulted in significant land cover change over a short time period. This study combined two types of remote sensing data, aerial imagery (RGB) and LiDAR, as the basis for quantifying land cover change in Christchurch between 2011 – 2015, a period corresponding to the five years immediately following the 22 February 2011 earthquake, which was part of the CES. An object based image analysis (OBIA) approach was adopted to classify the aerial imagery and LiDAR data into seven land cover types (bare land, building, grass, shadow, tree and water). The OBIA approach consisted of two steps, image segmentation and object classification. For the first step, this study used multi-level segmentation to better segment objects. For the second step, the random forest (RF) classifier was used to assign a land cover type to each object defined by the segmentation. Overall classification accuracies for 2011 and 2015 were 94.0% and 94.32%, respectively. Based on the classification result, land cover changes between 2011 and 2015 were then analysed. Significant increases were found in road and tree cover, while the land cover types that decreased were bare land, grass, roof, water. To better understand the reasons for those changes, land cover transitions were calculated. Canopy growth, seasonal differences and forest plantation establishment were the main reasons for tree cover increase. Redevelopment after the earthquake was the main reason for road area growth. By comparing the spatial distribution of these transitions, this study also identified Halswell and Wigram as the fastest developing suburbs in Christchurch. These results provided quantitative information for the effects of CES, with respect to land cover change. They allow for a better understanding for the current land cover status of Christchurch. Among those land cover changes, the significant increase in tree cover aroused particularly interest as urban forests benefit citizens via ecosystem services, including health, social, economic, and environmental benefits. Therefore, this study firstly calculated the percentages of tree cover in Christchurch’s fifteen wards in order to provide a general idea of tree cover change in the city extent. Following this, an automatic individual tree detection and crown delineation (ITCD) was undertaken to determine the feasibility of automated tree counting. The accuracies of the proposed approach ranged between 56.47% and 92.11% in thirty different sample plots, with an overall accuracy of 75.60%. Such varied accuracies were later found to be caused by the fixed tree detection window size and misclassifications from the land cover classification that affected the boundary of the CHM. Due to the large variability in accuracy, tree counting was not undertaken city-wide for both time periods. However, directions for further study for ITCD in Christchurch could be exploring ITCD approaches with variable window size or optimizing the classification approach to focus more on producing highly accurate CHMs.
This thesis examines the opportunities for young citizens in Christchurch to be engaged in city planning post-disaster. This qualitative study was conducted eight years after the 2010-2011 earthquakes and employed interviews with 18 young people aged between 12-24 years old, 14 of whom were already actively engaged in volunteering or participating in a youth council. It finds that despite having sought out opportunities for youth leadership and advocacy roles post-disaster, young people report frustration that they are excluded from decision-making and public life. These feelings of exclusion were described by young people as political, physical and social. Young people felt politically excluded from decision-making in the city, with some youth reporting that they did not feel listened to by decision-makers or able to make a difference. Physical exclusion was also experienced by the young people I interviewed, who reported that they felt excluded from their city and neighbourhood. This ranged from feeling unwelcome in certain parts of the city due to perceived social stratification, to actual exclusion from newly privatised areas in a post-quake recovery city. Social exclusion was reported by young people in the study in regard to their sense of marginalisation from the wider community, due to structural and social barriers. Among these, they observed a sense of prejudice towards them and other youth due to their age, class and/or ethnicity. The barriers to their participation and inclusion, and their aspirations for Christchurch post-disaster are discussed, as well as the implications of exclusion for young people’s wellbeing and sense of belonging. Results of this study contribute to the literature that challenges the sole focus on children and young peoples’ vulnerability post-disaster, reinforcing their capacity and desire to contribute to the recovery of their city and community (Peek, 2008). This research also challenges the narrative that young people are politically apathetic (Norris, 2004; Nissen, 2017), and adds to our understandings of the way that disasters can concentrate power amongst certain groups, in this case excluding young people generally from decision-making and public life. I conclude with some recommendations for a more robust post-disaster recovery in Christchurch, in ways that are more inclusive of young people and supportive of their wellbeing.
Background: We are in a period of history where natural disasters are increasing in both frequency and severity. They are having widespread impacts on communities, especially on vulnerable communities, those most affected who have the least ability to prepare or respond to a disaster. The ability to assemble and effectively manage Interagency Emergency Response Teams (IERTs) is critical to navigating the complexity and chaos found immediately following disasters. These teams play a crucial role in the multi-sectoral, multi-agency, multi-disciplinary, and inter-organisational response and are vital to ensuring the safety and well-being of vulnerable populations such as the young, aged, and socially and medically disadvantaged in disasters. Communication is key to the smooth operation of these teams. Most studies of the communication in IERTs during a disaster have been focussed at a macro-level of examining larger scale patterns and trends within organisations. Rarely found are micro-level analyses of interpersonal communication at the critical interfaces between collaborating agencies. This study set out to understand the experiences of those working at the interagency interfaces in an IERT set up by the Canterbury District Health Board to respond to the needs of the vulnerable people in the aftermath of the destructive earthquakes that hit Canterbury, New Zealand, in 2010-11. The aim of the study was to gain insights about the complexities of interpersonal communication (micro-level) involved in interagency response coordination and to generate an improved understanding into what stabilises the interagency communication interfaces between those agencies responding to a major disaster. Methods: A qualitative case study research design was employed to investigate how interagency communication interfaces were stabilised at the micro-level (“the case”) in the aftermath of the destructive earthquakes that hit Canterbury in 2010-11 (“the context”). Participant recruitment was undertaken by mapping which agencies were involved within the IERT and approaching representatives from each of these agencies. Data was collected via individual interviews using a semi-structured interview guide and was based on the “Critical Incident Technique”. Subsequently, data was transcribed verbatim and subjected to inductive analysis. This was underpinned theoretically by Weick’s “Interpretive Approach” and supported by Nvivo qualitative data analysis software. Results: 19 participants were interviewed in this study. Out of the inductive analysis emerged two primary themes, each with several sub-factors. The first major theme was destabilising/disruptive factors of interagency communication with five sub-factors, a) conflicting role mandates, b) rigid command structures, c) disruption of established communication structures, d) lack of shared language and understanding, and e) situational awareness disruption. The second major theme stabilising/steadying factors in interagency communication had four sub-factors, a) the establishment of the IERT, b) emergent novel communication strategies, c) establishment of a liaison role and d) pre-existing networks and relationships. Finally, there was a third sub-level identified during inductive analysis, where sub-factors from both primary themes were noted to be uniquely interconnected by emergent “consequences” arising out of the disaster context. Finally, findings were synthesised into a conceptual “Model of Interagency Communication at the Micro-level” based on this case study of the Canterbury earthquake disaster response. Discussion: The three key dimensions of The People, The Connections and The Improvisations served as a framework for the discussion of what stabilises interagency communication interfaces in a major disaster. The People were key to stabilising the interagency interfaces through functioning as a flexible conduit, guiding and navigating communication at the interagency interfaces and improving situational awareness. The Connections provided the collective competence, shared decision-making and prior established relationships that stabilised the micro-level communication at interagency interfaces. And finally, The Improvisations i.e., novel ideas and inventiveness that emerge out of rapidly changing post-disaster environments, also contributed to stabilisation of micro-level communication flows across interagency interfaces in the disaster response. “Command and control” hierarchical structures do provide clear processes and structures for teams working in disasters to follow. However, improvisations and novel solutions are also needed and often emerge from first responders (who are best placed to assess the evolving needs in a disaster where there is a high degree of uncertainty). Conclusion: This study highlights the value of incorporating an interface perspective into any study that seeks to understand the processes of IERTs during disaster responses. It also strengthens the requirement for disaster management frameworks to formally plan for and to allow for the adaptive responsiveness of local teams on the ground, and legitimise and recognise the improvisations of those in the role of emergent boundary spanners in a disaster response. This needs to be in addition to existing formal disaster response mechanisms. This study provides a new conceptual model that can be used to guide future case studies exploring stability at the interfaces of other IERTs and highlights the centrality of communication in the experiences of members of teams in the aftermath of a disaster. Utilising these new perspectives on stabilising communication at the interagency interfaces in disaster responses will have practical implications in the future to better serve the needs of vulnerable people who are at greatest risk of adverse outcomes in a disaster.
This thesis presents the findings from an experimental programme to determine the performance and behaviour of an integrated building incorporating low damage structural and non-structural systems. The systems investigated included post-tensioned rocking concrete frames, articulated floor solutions, low damage claddings and low damage partition systems. As part of a more general aim to increase the resilience of society against earthquake hazards, more emphasis has been given to damage-control design approaches in research. Multiple low-damage earthquake resistant structural and non-structural systems have emerged that are able to withstand high levels of drift or deflections will little or negligible residual. Dry jointed connections, articulated floor solutions, low damage cladding systems and low damage drywall partitions have all been developed separately and successfully tested. In spite of the extensive research effort and the adoption in practice of the low damage systems, work was required to integrate the systems within one building and verify the constructibility, behaviour and performance of the integrated systems. The objectives of this research were to perform dynamic experimental testing of a building which incorporated the low damage systems and acquire data which could be used to dynamically validate numerical models for each of the systems. A three phase experimental programme was devised and performed to dynamically test a half-scale two storey reinforced concrete building on the University of Canterbury shaking table. The three phases of the programme investigated: The structural system only. The rocking connections were tested as Post-Tensioned only connections and Hybrid connections (including dissipators). Two different articulated floor connections were also investigated. Non-structural systems. The Hybrid building was tested with each non-structural system separately; including low damage claddings, low damage partitions and traditional partitions. The Complete building was tested with Hybrid connections, low damage claddings and low damage partitions all integrated within the test specimen. The building was designed based on a full scale prototype building following the direct displacement based design to reach a peak inter-storey drift of 1.6% in a 1/500 year ground motion for a Wellington site. For each test set up, the test specimen was subjected to a ground motion sequence of 39 single direction ground motions. Through the sequence, both the local and global behaviours of the building and integrated systems were recorded in real time. The test specimen was subjected to over 400 ground motions throughout the testing programme. It sustained no significant damage that required reparations other than crumbling of the grout pads. The average peak inter-storey drifts of the buildings were lower than the design value of 1.6%. The low damage non-structural elements were undamaged in the ground motion sequence. The data acquired from each of the phases was used to successfully validate numerical models for each of the low damage systems included in the research.
Cats all over the world hunt wild animals and can contribute to the extinction of threatened species. In New Zealand, around half of all households have at least one cat. When cats live close to a natural area, such as a wetland, they may have impacts on native species. A previous study on the movements and hunting behaviour of domestic (house) cats around the Travis Wetland, Christchurch, New Zealand during 2000-2001 raised concerns about the effects of cats on the local skink population, as skinks were a frequent prey item. My study is a comparison to the prior study, to determine if impacts have changed alongside changes in human populations in the area post-earthquake. The domestic cat population in the area was estimated by a household survey in March-April 2018. For a 6 month period from March-September 2018, 26 households recorded prey brought home by their 41 cats. During April-July 2018, 14 cats wore Global Positioning System (GPS) devices for 7 days each to track their movements. Skink abundance was measured with pitfall trapping over 20 days in February 2018. There were more households in the area in 2018 than there were in 2000, but the numbers of cats had decreased. In the 196 ha study area around Travis Wetland, the domestic cat population was estimated at 429 cats, down from the previous 494. Most of the cats were free roaming, but the majority had been desexed and many were mostly seen at home. A total of 42 prey items were reported from 26 households and 41 cats over 6 months. Of these, 62% were rodents, 26% were exotic birds, and 12% were native birds. There were no native skinks, other mammals, or other vertebrates such as fish and amphibians (invertebrates were not included in this study). Eight male and six female cats were tracked by GPS. Home range sizes for the 100% minimum convex polygons (MCPs) ranged from 1.34 to 9.68 ha (mean 4.09 ha, median 3.54 ha). There were 9/14 (64%) cats that entered the edge of the wetland. Males had significantly larger home range areas at night and in general compared with females. However, age and distance of the cat’s household to the wetland did not have a significant effect on home range size and there was no significant correlation between home range size and prey retrieved. In 20 days of skink trapping, 11 Oligosoma polychroma were caught. The estimated catch rate was not significantly different from an earlier study on skink abundance in Travis Wetland. The apparently low abundance of skinks may have been the result of successful wetland restoration creating less suitable skink habitat, or of other predators other than cats. In the future, increased education should be provided to the public about ways to increase wildlife in their area. This includes creating lizard friendly habitat in their gardens and increasing management for cats. Generally, only a few cats bring home prey often, and these select cats should be identified in initial surveys and included in further studies. In New Zealand, until management programmes can target all predators in urban areas, domestic cats could stay out at night and inside during the day to help decrease the abundance of rodents at night and reduce the number of birds and lizards caught during the day.
Welcome to the Recover newsletter Issue 2 from the Marine Ecology Research Group (MERG) at the University of Canterbury. Recover is designed to keep you updated on our MBIE funded earthquake recovery project called RECOVER (Reef Ecology, Coastal Values & Earthquake Recovery). This second issue profiles some of the recent work done by our team out in the field!
Welcome to the first Recover newsletter from the Marine Ecology Research Group (MERG) at the University of Canterbury. Recover is designed to keep you updated on our MBIE funded earthquake recovery project called RECOVER (Reef Ecology, Coastal Values & Ecosystem Recovery). This first issue provides a summary of some of the big changes we’ve seen. In the next issue we’ll be profiling some of the current research as well as ways you can get involved!
Natural hazard reviews reveal increases in disaster impacts nowhere more pronounced than in coastal settlements. Despite efforts to enhance hazard resilience, the common trend remains to keep producing disaster prone places. This paper explicitly explores hazard versus multi-hazard concepts to illustrate how different conceptualizations can enhance or reduce settlement resilience. Understandings gained were combined with onthe-ground lessons from earthquake and flooding experiences to develop of a novel ‘first cut’ approach for analyzing key multi-hazard interconnections, and to evaluate resilience enhancing opportunities. Traditional disaster resilience efforts often consider different hazard types discretely. However, recent events in Christchurch, a New Zealand city that is part of the 100 Resilient Cities network, highlight the need to analyze the interrelated nature of different hazards, especially for enhancing lifelines system resilience. Our overview of the Christchurch case study demonstrates that seismic, hydrological, shallow-earth, and coastal hazards can be fundamentally interconnected, with catastrophic results where such interconnections go unrecognized. In response, we have begun to develop a simple approach for use by different stakeholders to support resilience planning, pre and post disaster, by: drawing attention to natural and built environment multi-hazard links in general; illustrating a ‘first cut’ tool for uncovering earthquake-flooding multi-hazard links in particular; and providing a basis for reviewing resilience strategy effectiveness in multi-hazard prone environments. This framework has particular application to tectonically active areas exposed to climate-change issues.
This paper explores the scope of small-scale radio to create an auditory geography of place. It focuses on the short term art radio project The Stadium Broadcast, which was staged in November 2014 in an earthquake-damaged sports stadium in Christchurch, New Zealand. Thousands of buildings and homes in Christchurch have been demolished since the Februrary 22, 2011 earthquake, and while Lancaster Park sports stadium is still standing, it has been unused since that date and its future remains uncertain. The Stadium Broadcast constructed a radio memorial to the Park’s 130 year history through archival recordings, the memories of local people, observation of its current state, and a performed site-specificity. The Stadium Broadcast reflected on the spatiality of radio sounds and transmissions, memory, post-disaster transitionality, and the im-permanence of place.
By closely examining the performance of a 22-storey steel framed building in Christchurch subject to various earthquakes over the past seven years, it is shown that a number of lessons can be learnt regarding the cost-effective consideration of non-structural elements. The first point in this work is that non-structural elements significantly affected the costs associated with repairing steel eccentrically braced frame (EBF) links. The decommissioning or rerouting of non-structural elements in the vicinity of damaged links in the case study building attributed to approximately half the total cost of their repair. Such costs could be significantly reduced if the original positioning of non-structural elements took account of the potential need to repair the EBF links. The second point highlighted is the role that pre-cast cladding apparently played on the distribution and type of damage in the building. Loss estimates obtained following the FEMA P-58 framework vary considerably when cladding is or isnt modelled, both because of changes to drift demands up the height of the building and because certain types of subsequent damage are likely to be cheaper to repair than others. Finally, costly repairs to non-structural partition walls were required not only after the moment magnitude 7.1 earthquake in 2010 but also in multiple aftershocks in the years that followed. Repair costs associated with aftershock events exceeded those from the main event, emphasizing the need to consider aftershocks within modern performance-based earthquake engineering and also the opportunity that exists to make more cost-effective repair strategies following damaging earthquakes.
Observations made in past earthquakes, in New Zealand and around the world, have highlighted the vulnerability of non-structural elements such as facades, ceilings, partitions and services. Damage to these elements can be life-threatening or jeopardise egress routes but typically, the main concern is the cost and time associated with repair works. The Insurance Council of New Zealand highlighted the substantial economic losses in recent earthquakes due to poor performance of non-structural elements. Previous inspections and research have attributed the damage to non-structural elements principally to poor coordination, inadequate or lack of seismic restraints and insufficient clearances to cater for seismic actions. Secondary issues of design responsibility, procurement and the need for better alignment of the various Standards have been identified. In addition to the compliance issues, researchers have also demonstrated that current code provisions for non-structural elements, both in New Zealand and abroad, may be inadequate. This paper first reviews the damage observed against the requirements of relevant Standards and the New Zealand Building Code, and it appears that, had the installations been compliant, the cost of repair and business interruption would have been substantially less. The second part of the paper highlights some of the apparent shortcomings with the current design process for non-structural elements, points towards possible alternative strategies and identifies areas where more research is deemed necessary. The challenge of improving the seismic performance of non-structural elements is a complex one across a diverse construction industry. Indications are that the New Zealand construction industry needs to completely rethink the delivery approach to ensure an integrated design, construction and certification process. The industry, QuakeCentre, QuakeCoRE and the University of Canterbury are presently working together to progress solutions. Indications are that if new processes can be initiated, better performance during earthquakes will be achieved while delivering enhanced building and business resilience.
