There has not been substantial research conducted in the area of fraud and natural disasters. Therefore, this study sought to examine the perceptions of Canterbury residents toward the recovery process following the September 2010 and February 2011 earthquakes and whether residents felt as though contractor fraud occurs in Canterbury. A questionnaire was developed to gauge information about Canterbury residents’ self-reports involving the earthquakes, specific contractors involved, parties involved with the recovery process in general, and demographic information. Participants included a total of 213 residents from the Canterbury region who had been involved with contractors and/or insurance companies due to the recovery process. Results indicated that a high percentage of the participants were not satisfied with the recovery process and that almost half of the participants reported feeling scammed by contractors in Canterbury after the 2010 and 2011 earthquakes. Moreover, the results indicate that participants neither agreed with the assessments made about their property losses nor the plans made to recover their properties. In many cases, participants felt pressured and even reluctant to accept these assessments and/or plans. The present study does not seek to explain why contractor fraud exists or what motivates scammers. Conversely, it attempts to demonstrate the perceptions of contractor fraud and satisfaction that have taken place in the aftermath of the Canterbury earthquakes.
Documenting earthquake-induced ground deformation is significant to assess the characteristics of past and contemporary earthquakes and provide insight into seismic hazard. This study uses airborne light detection and ranging (LiDAR) and conducts multi-disciplinary field techniques to document the surface rupture morphology and evaluate the paleoseismicity and seismic hazard parameters of the Hurunui segment of the Hope Fault in the northern South Island of New Zealand. It also documents and evaluates seismically induced features and ground motion characteristics of the 2010 Darfield and 2011 Christchurch earthquakes in the Port Hills, south of Christchurch. These two studies are linked in that they investigate the near-field coseismic features of large (Mw ~7.1) earthquakes in New Zealand and produce data for evaluating seismic hazards of future earthquakes. In the northern South Island of New Zealand, the Australian-Pacific plate boundary is characterised by strike-slip deformation across the Marlborough Fault System (MFS). The ENE-striking Hope Fault (length: ~230 km) is the youngest and southernmost fault in the MFS, and the second fastest slipping fault in New Zealand. The Hope Fault is a major source of seismic hazard in New Zealand and has ruptured (in-part) historically in the Mw 7.1 1888 Amuri earthquake. In the west, the Hurunui segment of the Hope Fault is covered by beech forest. Hence, its seismic hazard parameters and paleoearthquake chronology were poorly constrained and it was unknown whether the 1888 earthquake ruptured this segment or not and if so, to what extent. Utilising LiDAR and field data, a 29 km-long section of the Hurunui segment of the Hope Fault is mapped. LiDAR-mapping clearly reveals the principal slip zone (PSZ) of the fault and a suite of previously unrecognised structures that form the fault deformation zone (FDZ). FDZ width measurements from 415 locations reveal a spatially-variable, active FDZ up to ~500 m wide with an average width of 200 m. Kinematic analysis of the fault structures shows that the Hurunui segment strikes between 070° and 075° and is optimally oriented for dextral strike-slip within the regional stress field. This implies that the wide FDZ observed is unlikely to result from large-scale fault mis-orientation with respect to regional stresses. The analysis of FDZ width indicates that it increases with increased hanging wall topography and increased topographic relief suggesting that along-strike topographic perturbations to fault geometry and stress states increase fault zone complexity and width. FDZ width also increases where the tips of adjacent PSZ strands locally vary in strike, and where the thickness of alluvial deposits overlying bedrock increases. LiDAR- and photogrammetrically-derived topographic mapping indicates that the boundary between the Hurunui and Hope River segments is characterised by a ~850-m-wide right stepover and a 9º-14° fault bend. Paleoseismic trenching at Hope Shelter site reveals that 6 earthquakes occurred at A.D. 1888, 1740-1840, 1479-1623, 819-1092, 439-551, and 373- 419. These rupture events have a mean recurrence interval of ~298 ± 88 yr and inter-event times ranging from 98 to 595 yrs. The variation in the inter-event times is explained by (1) coalescing rupture overlap from the adjacent Hope River segment on to the Hurunui segment at the study site, (2) temporal clustering of large earthquakes on the Hurunui segment, and/or (3) ‘missing’ rupture events. It appears that the first two options are more plausible to explain the earthquake chronologies and rupture behaviour on the Hurunui segment, given the detailed nature of the geologic and chronologic investigations. This study provides first evidence for coseismic multi-segment ruptures on the Hope Fault by identifying a rupture length of 44-70 km for the 1888 earthquake, which was not confined to the Hope River segment (primary source for the 1888 earthquake). LiDAR data is also used to identify and measure dextral displacements and scarp heights from the PSZ and structures within the FDZ along the Hurunui segment. Reconstruction of large dextrally-offset geomorphic features shows that the vertical component of slip accounts for only ~1% of the horizontal displacements and confirms that the fault is predominantly strike-slip. A strong correlation exists between the dextral displacements and elevations of geomorphic features suggesting the possibility of age correlation between the geomorphic features. A mean single event displacement (SED) of 3.6 ± 0.7 m is determined from interpretation of sets of dextral displacements of ≤ 25 m. Using the available surface age data and the cumulative dextral displacements from Matagouri Flat, McKenzie Fan, Macs Knob and Hope River sites, and the mean SED, a mean slip rate of 12.2 ± 2.4 mm/yr, and a mean recurrence interval of ~320 ± 120 yr, and a potential earthquake magnitude of Mw 7.2 are determined for the Hurunui segment. This study suggests that the fault slip rate has been constant over the last ~15000 yr. Strong ground motions from the 2010 Darfield (Canterbury) earthquake displaced boulders and caused ground damage on some ridge crests in the Port Hills. However, the 2011 Christchurch earthquake neither displaced boulders nor caused ground damage at the same ridge crests. Documentation of locations (~400 m a.s.l.), lateral displacements (8-970 cm), displacement direction (250° ± 20°) of displaced boulders, in addition to their hosting socket geometries (< 1 cm to 50 cm depth), the orientation of the ridges (000°-015°) indicate that boulders have been displaced in the direction of instrumentally recorded transient peak ground horizontal displacements nearby and that the seismic waves have been amplified at the study sites. The co-existence of displaced and non-displaced boulders at proximal sites suggests small-scale ground motion variability and/or varying boulder-ground dynamic interactions relating to shallow phenomena such as variability in soil depth, bedrock fracture density and/or microtopography on the bedrock-soil interface. Shorter shaking duration of the 2011 Christchurch event, differing frequency contents and different source characteristics were all factors that may have contributed to generating circumstances less favourable to boulder displacement in this earthquake. Investigating seismically induced features, fault behaviour, site effects on the rupture behaviour, and site response to the seismic waves provides insights into fault rupture hazards.
INTRODUCTION: There is little research on the role of creative arts and craft in disaster recovery. This article reports findings about the emergent role of crafting from research conducted after the 2010–2011 series of earthquakes in Christchurch and surrounding districts in Aotearoa New Zealand. In particular, the article focuses on the significance and differing interpretations of the notion of place expressed by participants through their craftwork, in this case led by women and mediated by the post-earthquake geographic and temporal context. METHOD: This qualitative research included nine individual interviews and five focus group interviews with crafters from Christchurch and surrounding districts. There were 35 participants in total, 33 were women. Applied thematic analysis was used to code the data and identify themes. These themes included connection to place, the symbolism of craft, the healing experience of craft groups and places for women. The notion of place was evident across all three themes. FINDINGS: The findings from the research demonstrate differing ways in which the significance of place was reflected in the craftwork. Participants interpreted the concept of place in descriptive, symbolic, and therapeutic ways. IMPLICATIONS: More understanding about the way creative endeavours like crafting can be used to help ameliorate the impact of natural disasters is needed. Social work practitioners are encouraged to explore place-based wellbeing during their work with service users and to include aspects of artistry, craft and creativity.
During 2010 and 2011, a series of major earthquakes caused widespread damage in the city of Christchurch, New Zealand. The magnitude 6.3 quake in February 2011 caused 185 fatalities. In the ensuing months, the government progressively zoned residential land in Christchurch on the basis of its suitability for future occupation (considering damage from these quakes and future earthquake risk). Over 6,000 homes were placed in the ‘red-zone’, meaning that property owners were forced to sell their land to the Crown. This study analysed patterns of residential mobility amongst thirty-one red-zone households from the suburb of Southshore, Christchurch. Drawing on interviews and surveys, the research traced their experience from the zoning announcement until they had moved to a new residence. The research distinguished between short (before the zoning announcement) and long term (post the red zone ‘deadline’) forms of household relocation. The majority of households in the study were highly resistant to short term movement. Amongst those which did relocate before the zoning decision, the desire to maintain a valued social connection with a person outside of the earthquake environment was often an important factor. Some households also moved out of perceived necessity (e.g. due to lack of power or water). In terms of long-term relocation, concepts of affordability and safety were much more highly valued by the sample when purchasing post-quake property. This resulted in a distinct patterning of post-quake housing location choices. Perceived control over the moving process, relationship with government organisations and insurance companies, and time spent in the red-zone before moving all heavily influenced participants’ disaster experience. Contrary to previous studies, households in this study recorded higher levels of subjective well-being after relocating. The study proposed a typology of movers in the Christchurch post-disaster environment. Four mobility behaviours, or types, are identified: the Committed Stayers (CSs), the Environment Re-Creators (ERCs), the Resigned Acceptors (RAs), and the Opportunistic Movers (OMs). The CSs were defined by their immobility rather than their relocation aspirations, whilst the ERCs attempted to recreate or retain aspects of Southshore through their mobility. The RAs expressed a form of apathy towards the post-quake environment, whereas, on the other hand, the OMs moved relative to pre-earthquake plans, or opportunities that arose from the earthquake itself. Possibilities for further research include examining household adaptability to new residential environments and tracking further mobility patterns in the years following relocation from the red- zone.
Sewerage systems convey sewage, or wastewater, from residential or commercial buildings through complex reticulation networks to treatment plants. During seismic events both transient ground motion and permanent ground deformation can induce physical damage to sewerage system components, limiting or impeding the operability of the whole system. The malfunction of municipal sewerage systems can result in the pollution of nearby waterways through discharge of untreated sewage, pose a public health threat by preventing the use of appropriate sanitation facilities, and cause serious inconvenience for rescuers and residents. Christchurch, the second largest city in New Zealand, was seriously affected by the Canterbury Earthquake Sequence (CES) in 2010-2011. The CES imposed widespread damage to the Christchurch sewerage system (CSS), causing a significant loss of functionality and serviceability to the system. The Christchurch City Council (CCC) relied heavily on temporary sewerage services for several months following the CES. The temporary services were supported by use of chemical and portable toilets to supplement the damaged wastewater system. The rebuild delivery agency -Stronger Christchurch Infrastructure Rebuild Team (SCIRT) was created to be responsible for repair of 85 % of the damaged horizontal infrastructure (i.e., water, wastewater, stormwater systems, and roads) in Christchurch. Numerous initiatives to create platforms/tools aiming to, on the one hand, support the understanding, management and mitigation of seismic risk for infrastructure prior to disasters, and on the other hand, to support the decision-making for post-disaster reconstruction and recovery, have been promoted worldwide. Despite this, the CES in New Zealand highlighted that none of the existing platforms/tools are either accessible and/or readable or usable by emergency managers and decision makers for restoring the CSS. Furthermore, the majority of existing tools have a sole focus on the engineering perspective, while the holistic process of formulating recovery decisions is based on system-wide approach, where a variety of factors in addition to technical considerations are involved. Lastly, there is a paucity of studies focused on the tools and frameworks for supporting decision-making specifically on sewerage system restoration after earthquakes. This thesis develops a decision support framework for sewerage pipe and system restoration after earthquakes, building on the experience and learning of the organisations involved in recovering the CSS following the CES in 2010-2011. The proposed decision support framework includes three modules: 1) Physical Damage Module (PDM); 2) Functional Impact Module (FIM); 3) Pipeline Restoration Module (PRM). The PDM provides seismic fragility matrices and functions for sewer gravity and pressure pipelines for predicting earthquake-induced physical damage, categorised by pipe materials and liquefaction zones. The FIM demonstrates a set of performance indicators that are categorised in five domains: structural, hydraulic, environmental, social and economic domains. These performance indicators are used to assess loss of wastewater system service and the induced functional impacts in three different phases: emergency response, short-term recovery and long-term restoration. Based on the knowledge of the physical and functional status-quo of the sewerage systems post-earthquake captured through the PDM and FIM, the PRM estimates restoration time of sewer networks by use of restoration models developed using a Random Forest technique and graphically represented in terms of restoration curves. The development of a decision support framework for sewer recovery after earthquakes enables decision makers to assess physical damage, evaluate functional impacts relating to hydraulic, environmental, structural, economic and social contexts, and to predict restoration time of sewerage systems. Furthermore, the decision support framework can be potentially employed to underpin system maintenance and upgrade by guiding system rehabilitation and to monitor system behaviours during business-as-usual time. In conjunction with expert judgement and best practices, this framework can be moreover applied to assist asset managers in targeting the inclusion of system resilience as part of asset maintenance programmes.
The assessment of damage and remaining capacity after an earthquake is an immediate measure to determine whether a reinforced concrete (RC) building is usable and safe for occupants. The recent Christchurch earthquake (22 February 2011) caused a uniquely severe level of structural damage to modern buildings, resulting in extensive damage to the building stock. About 60% of damaged multistorey concrete buildings (3 storeys and up) were demolished after the earthquake, and the cost of reconstruction amounted to 40 billion NZD. The aftermath disclosed issues of great complexities regarding the future of the RC buildings damaged by the earthquakes. This highlighted the importance of post-event decision-making, as the outcome will allow the appropriate course of action—demolition, repair or acceptance of the existing building—to be considered. To adopt the proper strategy, accurate assessment of the residual capacity and the level of damage is required. This doctoral dissertation aims to assess the damage and remaining capacity at constituent material and member level (i.e., concrete material and beams) through a systematic approach in an attempt to address part of an existing gap in the available literature. Since the residual capacity of RC members is not unique and depends on previously applied loading history, post-event residual capacity in this study was assessed in terms of fraction of fatigue life (i.e., the number of cycles required to failure). This research comprises three main parts: (1) residual capacity and damage assessment at material level (i.e., concrete), (2) post-yield bond deterioration and damage assessment at the interface of steel and concrete, and, finally, (3) residual capacity and damage assessment at member level (i.e., RC beam). The first part of this research focused on damage assessment and the remaining capacity of concrete from a material point of view. It aimed to employ appropriate and reliable durability-based testing and image-detection techniques to quantify deterioration in the mechanical properties of concrete on the basis that stress-induced damage occurred in the microstructural system of the concrete material. To this end, in the first phase, a feasibility study was conducted in which a combination of oxygen permeability, electrical resistivity and porosity tests were assessed to determine if they were robust and reliable enough to reveal damage which occurred in the microstructural system of concrete. The results, in terms of change in permeability, electrical resistivity and porosity features of disk samples taken from the middle third of damaged concrete cylinders (200 mm × 100 mm) monotonically pre-loaded to 50%, 70%, 90% and 95% of the ultimate strength (f′c), showed the permeability test is a reliable tool to identify the degree of damage, due to its high sensitivity to the load-induced microcracking. In parallel, to determine the residual capacity, the companion damaged concrete cylinders already loaded to the same level of compressive strength were reloaded up to failure. Comparing the stress–strain relationship of damaged concrete with intact material, it was also found that the strain capacity of the reloaded pre-damaged concrete cylinders decreases while strength remained virtually unchanged. In the second phase of the first part, a fluorescent microscopy technique was used to assess the damage and develop a correlation between material degradation, by virtue of the geometrical features, and damage to the concrete. To account for the effect of confinement and cyclic loading, in the third phase, the residual capacity and damage assessment of unconfined and GFRP confined concrete cylinders subjected to low-cycle fatigue loading, was investigated. Similar to the first phase, permeability testing technique was used to provide an indirect evaluation of fatigue damage. Finally, in the fourth phase of the first part, the suitability of permeability testing technique to assess damage was evaluated for cored concrete taken from three types of RC members: columns, beams and a beam-column joint. In view of the fact that the composite action of an RC member is highly dependent on the bond between reinforcement and surrounding concrete, understanding the deterioration of the bond in the post-yield range of strain in steel was crucial to assess damage at member level. Therefore, in the second phase of this research, a state-of-the- art distributed fibre optic strain sensor system (DFOSSS) system was used to evaluate bond deterioration in a cantilever RC beam subjected to monotonic lateral loading. The technology allowed the continuous capture of strain, every 2.6 mm along the length, in both reinforcing bars and cover concrete. The strain profile provided a basis by which the slip, axial stress and bond stress distributions were then established. In the third part, the study focused on the damage assessment and residual capacity of seven half-scale RC beams subjected to a constant-amplitude cyclic loading protocol. In the first stage, the structural performances of three specimens under constant-amplitude fatigue at 1%, 2% and 4% chord rotation (drift) were examined. In parallel, the number of cycles to failure, degradation in strength, stiffness and energy dissipation were characterized. In the second stage, four RC beams were subjected to loading up to 70% and 90% of their fatigue life, at 2% and 4% drift, and then monotonically pulled up to failure. To determine the residual flexural capacity, the lateral force–displacement results of pre-damaged specimens were compared with an undamaged specimen subjected to only monotonic loading. The study showed significant losses in strength, deformability, stiffness and energy dissipation capacity. A nonlinear finite element analysis (FEA) using concrete damage plasticity (CDP) model was also conducted in ABAQUS to numerically investigate the behaviour of the tested specimen. The results of the FE simulations indicated a reasonable response compared with the behaviour of the test specimen in terms of force–displacement and cracking pattern. During the Christchurch earthquake it was observed that the loading history has a significant influence on structural responses. While in conventional pseudo-static loading protocol, internal forces can be redistributed along the plastic length: there is little chance for structures undergoing high initial loading amplitude to redistribute pertinent stresses. As a result, in the third phase of this part, the effect of high rate of loading on the behaviour of seismically designed RC beams was investigated. Two half-scale cantilever RC beams were subjected to similar constant-amplitude cyclic loading at 2% and 4% drifts, but at a rate of 500 mm/s. Due to the incapability of conventional measuring techniques, a motion-tracking system was employed for data acquisition with the high-speed tests. The effect of rate of loading on the fatigue life of specimens (i.e., the number of cycles required to failure), secant stiffness, failure mode, cracking pattern, beam elongations and bar fracture surface were analysed. Integrating the results of all parts of this research has resulted in a better understanding of residual capacity and the development of damage at both the material and member level by using a low-cycle fatigue approach.
This dissertation addresses a diverse range of topics in the physics-based broadband ground motion simulation, with a focus on New Zealand applications. In particular the following topics are addressed: the methodology and computational implementation of a New Zealand Velocity Model for broadband ground motion simulation; generalised parametric functions and spatial correlations for seismic velocities in the Canterbury, New Zealand region from surface-wave-based site characterisation; and ground motion simulations of Hope Fault earthquakes. The paragraphs below outline each contribution in more detail. A necessary component in physics-based ground motion simulation is a 3D model which details the seismic velocities in the region of interest. Here a velocity model construction methodology, its computational implementation, and application in the construction of a New Zealand velocity model for use in physics-based broadband ground motion simulation are presented. The methodology utilises multiple datasets spanning different length scales, which is enabled via the use of modular sub-regions, geologic surfaces, and parametric representations of crustal velocity. A number of efficiency-related workflows to decrease the overall computational construction time are employed, while maintaining the flexibility and extensibility to incorporate additional datasets and re- fined velocity parameterizations as they become available. The model comprises explicit representations of the Canterbury, Wellington, Nelson-Tasman, Kaikoura, Marlborough, Waiau, Hanmer and Cheviot sedimentary basins embedded within a regional travel-time tomography-based velocity model for the shallow crust and provides the means to conduct ground motion simulations throughout New Zealand for the first time. Recently developed deep shear-wave velocity profiles in Canterbury enabled models that better characterise the velocity structure within geologic layers of the Canterbury sedimentary basin to be developed. Here the development of depth- and Vs30-dependent para-metric velocity and spatial correlation models to characterise shear-wave velocities within the geologic layers of the Canterbury sedimentary basin are presented. The models utilise data from 22 shear-wave velocity profiles of up to 2.5km depth (derived from surface wave analysis) juxtaposed with models which detail the three-dimensional structure of the geologic formations in the Canterbury sedimentary basin. Parametric velocity equations are presented for Fine Grained Sediments, Gravels, and Tertiary layer groupings. Spatial correlations were developed and applied to generate three-dimensional stochastic velocity perturbations. Collectively, these models enable seismic velocities to be realistically represented for applications such as 3D ground motion and site response simulations. Lastly the New Zealand velocity model is applied to simulate ground motions for a Mw7.51 rupture of the Hope Fault using a physics-based simulation methodology and a 3D crustal velocity model of New Zealand. The simulation methodology was validated for use in the region through comparison with observations for a suite of historic small magnitude earthquakes located proximal to the Hope Fault. Simulations are compared with conventionally utilised empirical ground motion models, with simulated peak ground velocities being notably higher in regions with modelled sedimentary basins. A sensitivity analysis was undertaken where the source characteristics of magnitude, stress parameter, hypocentre location and kinematic slip distribution were varied and an analysis of their effect on ground motion intensities is presented. It was found that the magnitude and stress parameter strongly influenced long and short period ground motion amplitudes, respectively. Ground motion intensities for the Hope Fault scenario are compared with the 2016 Kaikoura Mw7.8 earthquake, it was found that the Kaikoura earthquake produced stronger motions along the eastern South Island, while the Hope Fault scenario resulted in stronger motions immediately West of the near-fault region. The simulated ground motions for this scenario complement prior empirically-based estimates and are informative for mitigation and emergency planning purposes.
On 22 February 2011，a magnitude Mw 6.3 earthquake occurred with an epicenter located near Lyttelton at about 10km from Christchurch in Canterbury region on the South Island of New Zealand (Figure 1). Since this earthquake occurred in the midst of the aftershock activity which had continued since the 4 September 2010 Darfield Earthquake occurrence, it was considered to be an aftershock of the initial earthquake. Because of the short distance to the city and the shallower depth of the epicenter, this earthquake caused more significant damage to pipelines, traffic facilities, residential houses/properties and multi-story buildings in the central business district than the September 2010 Darfield Earthquake in spite of its smaller earthquake magnitude. Unfortunately, this earthquake resulted in significant number of casualties due to the collapse of multi-story buildings and unreinforced masonry structures in the city center of Christchurch. As of 4 April, 172 casualties were reported and the final death toll is expected to be 181. While it is extremely regrettable that Christchurch suffered a terrible number of victims, civil and geotechnical engineers have this hard-to-find opportunity to learn the response of real ground from two gigantic earthquakes which occurred in less than six months from each other. From geotechnical engineering point of view, it is interesting to discuss the widespread liquefaction in natural sediments, repeated liquefaction within short period and further damage to earth structures which have been damaged in the previous earthquake. Following the earthquake, an intensive geotechnical reconnaissance was conducted to capture evidence and perishable data from this event. The team included the following members: Misko Cubrinovski (University of Canterbury, NZ, Team Leader), Susumu Yasuda (Tokyo Denki University, Japan, JGS Team Leader), Rolando Orense (University of Auckland, NZ), Kohji Tokimatsu (Tokyo Institute of Technology, Japan), Ryosuke Uzuoka (Tokushima University, Japan), Takashi Kiyota (University of Tokyo, Japan), Yasuyo Hosono (Toyohashi University of Technology, Japan) and Suguru Yamada (University of Tokyo, Japan).
Background The 2010/2011 Canterbury earthquakes and aftershocks in New Zealand caused unprecedented destruction to the physical, social, economic, and community fabric of Christchurch city. The recovery phase in Christchurch is on going, six years following the initial earthquake. Research exploring how disabled populations experience community inclusion in the longer-term recovery following natural disasters is scant. Yet such information is vital to ensure that recovering communities are inclusive for all members of the affected population. This thesis specifically examined how people who use wheelchairs experienced community inclusion four years following the 2010/2011 Canterbury earthquakes. Aims The primary research aim was to understand how one section of the disability community – people who use wheelchairs – experienced community inclusion over the four years following the 2010/2011 Canterbury earthquakes and aftershocks. A secondary aim was to test a novel sampling approach, Respondent Driven Sampling, which had the potential to enable unbiased population-based estimates. This was motivated by the lack of an available sampling frame for the target population, which would inhibit recruitment of a representative sample. Methodology and methods An exploratory sequential mixed methods design was used, beginning with a qualitative phase (Phase One), which informed a second quantitative phase (Phase Two). The qualitative phase had two stages. First, a small sample of people who use wheelchairs participated in an individual, semi-structured interview. In the second stage, these participants were then invited to a group interview to clarify and prioritise themes identified in the individual interviews. The quantitative phase was a cross-sectional survey developed from the findings from Phase One. Initially, Respondent Driven Sampling was employed to conduct a national, electronic cross-sectional survey that aimed to recruit a sample that may provide unbiased population-based estimates. Following the unsuccessful application of Respondent Driven Sampling, a region-specific convenience sampling approach was used. The datasets from the qualitative and quantitative phases were integrated to address the primary aim of the research. Results In Phase One 13 participants completed the individual interviews, and five of them contributed to the group interview. Thematic analysis of individual and group interview data suggested that participants felt the 2010/11 earthquakes magnified many pre-existing barriers to community inclusion, and also created an exciting opportunity for change. This finding was encapsulated in five themes: 1) earthquakes magnified barriers, 2) community inclusion requires energy, 3) social connections are important, 4) an opportunity lost, and 5) an opportunity found. The findings from Phase One informed the development of a survey instrument to investigate how these findings generalised to a larger sample of individuals who use wheelchairs. In Phase Two, the Respondent Driven Sampling approach failed to recruit enough participants to satisfy the statistical requirements needed to reach equilibrium, thereby enabling the calculation of unbiased population estimates. The subsequent convenience sampling approach recruited 49 participants who, combined with the 15 participants from the Respondent Driven Sampling approach that remained eligible for the region-specific sample, resulted in the total of 64 individuals who used wheelchairs and were residents of Christchurch. Participants reported their level of community inclusion at three time periods: the six months prior to the first earthquake in September 2010 (time one), the six months following the first earthquake in September 2010 (time two), and the six months prior to survey completion (between October 2015 and March 2016, (time three)). Survey data provided some precision regarding the timing in which the magnified barriers developed. Difficulty with community inclusion rose significantly between time one and time two, and while reducing slightly, was still present during time three, and had not returned to the time one baseline. The integrated findings from Phase One and Phase Two suggested that magnified barriers to community inclusion had been sustained four years post-earthquake, and community access had not returned to pre-earthquake levels, let alone improved beyond pre-earthquake levels. Conclusion Findings from this mixed methods study suggest that four years following the initial earthquake, participants were still experiencing multiple magnified barriers, which contributed to physical and social exclusion, as well as fatigue, as participants relied on individual agency to negotiate such barriers. Participants also highlighted the exciting opportunity to create an accessible city. However because they were still experiencing barriers four years following the initial event, and were concerned that this opportunity might be lost if the recovery proceeds without commitment and awareness from the numerous stakeholders involved in guiding the recovery. To truly realise the opportunity to create an accessible city following a disaster, the transition from the response phase to a sustainable longer-term recovery must adopt a new model of community engagement where decision-makers partner with people living with disability to co-produce a vision and strategy for creating an inclusive community. Furthermore, despite the unsuccessful use of Respondent Driven Sampling in this study, future research exploring the application of RDS with wheelchair users is recommended before discounting this sampling approach in this population.
This document reviews research-based understandings of the concept of resilience. A conceptual model is developed which identifies a number of the factors that influence individual and household resilience. Guided by the model, a series of recommendations are developed for practices that will support individual and household resilience in Canterbury in the aftermath of the 2010-2011 earthquakes.
Welcome to the Recover newsletter Issue 6 from the Marine Ecology Research Group (MERG) of 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 6th instalment features the ‘new land’ created by the earthquake uplift of the coastline, recreational uses of beaches in Marlborough, and pāua survey work and hatchery projects with our partners in Kaikōura.
Geologic phenomena produced by earthquake shaking, including rockfalls and liquefaction features, provide important information on the intensity and spatiotemporal distribution of earthquake ground motions. The study of rockfall and liquefaction features produced in contemporary well- instrumented earthquakes increases our knowledge of how natural and anthropogenic environments respond to earthquakes and improves our ability to deduce seismologic information from analogous pre-contemporary (paleo-) geologic features. The study of contemporary and paleo- rockfall and liquefaction features enables improved forecasting of environmental responses to future earthquakes. In this thesis I utilize a combination of field and imagery-based mapping, trenching, stratigraphy, and numerical dating techniques to understand the nature and timing of rockfalls (and hillslope sedimentation) and liquefaction in the eastern South Island of New Zealand, and to examine the influence that anthropogenic activity has had on the geologic expressions of earthquake phenomena. At Rapaki (Banks Peninsula, NZ), field and imagery-based mapping, statistical analysis and numerical modeling was conducted on rockfall boulders triggered by the fatal 2011 Christchurch earthquakes (n=285) and compared with newly identified prehistoric (Holocene and Pleistocene) boulders (n=1049) deposited on the same hillslope. A significant population of modern boulders (n=26) travelled farther downslope (>150 m) than their most-travelled prehistoric counterparts, causing extensive damage to residential dwellings at the foot of the hillslope. Replication of prehistoric boulder distributions using 3-dimensional rigid body numerical models requires the application of a drag-coefficient, attributed to moderate to dense slope vegetation, to account for their spatial distribution. Radiocarbon dating provides evidence for 17th to early 20th century deforestation at the study site during Polynesian and European colonization and after emplacement of prehistoric rockfalls. Anthropocene deforestation enabled modern rockfalls to exceed the limits of their prehistoric predecessors, highlighting a shift in the geologic expression of rockfalls due to anthropogenic activity. Optical and radiocarbon dating of loessic hillslope sediments in New Zealand’s South Island is used to constrain the timing of prehistoric rockfalls and associated seismic events, and quantify spatial and temporal patterns of hillslope sedimentation including responses to seismic and anthropogenic forcing. Luminescence ages from loessic sediments constrain timing of boulder emplacement to between ~3.0 and ~12.5 ka, well before the arrival of Polynesians (ca AD 1280) and Europeans (ca AD 1800) in New Zealand, and suggest loess accumulation was continuing at the study site until 12-13 ka. Large (>5 m3) prehistoric rockfall boulders preserve an important record of Holocene hillslope sedimentation by creating local traps for sediment aggradation and upbuilding soil formation. Sediment accumulation rates increased considerably (>~10 factor increase) following human arrival and associated anthropogenic burning of hillslope vegetation. New numerical ages are presented to place the evolution of loess-mantled hillslopes in New Zealand’s South Island into a longer temporal framework and highlight the roles of earthquakes and humans on hillslope surface process. Extensive field mapping and characterization for 1733 individual prehistoric rockfall boulders was conducted at Rapaki and another Banks Peninsula site, Purau, to understand their origin, frequency, and spatial and volumetric distributions. Boulder characteristics and distributions were compared to 421 boulders deposited at the same sites during the 2010-2011 Canterbury earthquake sequence. Prehistoric boulders at Rapaki and Purau are comprised of two dominant lithofacies types: volcanic breccia and massive (coherent) lava basalt. Volcanic breccia boulders are found in greatest abundance (64-73% of total mapped rockfall) and volume (~90-96% of total rockfall) at both locations and exclusively comprise the largest boulders with the longest runout distances that pose the greatest hazard to life and property. This study highlights the primary influence that volcanic lithofacies architecture has on rockfall hazard. The influence of anthropogenic modifications on the surface and subsurface geologic expression of contemporary liquefaction created during the 2010-2011 Canterbury earthquake sequence (CES) in eastern Christchurch is examined. Trench observations indicate that anthropogenic fill layer boundaries and the composition/texture of discretely placed fill layers play an important role in absorbing fluidized sand/silt and controlling the subsurface architecture of preserved liquefaction features. Surface liquefaction morphologies (i.e. sand blows and linear sand blow arrays) display alignment with existing utility lines and utility excavations (and perforated pipes) provided conduits for liquefaction ejecta during the CES. No evidence of pre-CES liquefaction was identified within the anthropogenic fill layers or underlying native sediment. Radiocarbon dating of charcoal within the youngest native sediment suggests liquefaction has not occurred at the study site for at least the past 750-800 years. The importance of systematically examining the impact of buried infrastructure on channelizing and influencing surface and subsurface liquefaction morphologies is demonstrated. This thesis highlights the importance of using a multi-technique approach for understanding prehistoric and contemporary earthquake phenomena and emphasizes the critical role that humans play in shaping the geologic record and Earth’s surface processes.
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This presentation discusses recent empirical ground motion modelling efforts in New Zealand. Firstly, the active shallow crustal and subduction interface and slab ground motion prediction equations (GMPEs) which are employed in the 2010 update of the national seismic hazard model (NSHM) are discussed. Other NZ-specific GMPEs developed, but not incorporated in the 2010 update are then discussed, in particular, the active shallow crustal model of Bradley (2010). A brief comparison of the NZ-specific GMPEs with the near-source ground motions recorded in the Canterbury earthquakes is then presented, given that these recordings collectively provide a significant increase in observed strong motions in the NZ catalogue. The ground motion prediction expert elicitation process that was undertaken following the Canterbury earthquakes for active shallow crustal earthquakes is then discussed. Finally, ongoing GMPE-related activities are discussed including: ground motion and metadata database refinement, improved site characterization of strong motion station, and predictions for subduction zone earthquakes.
Following the Mw 6.2 Christchurch Earthquake on 22 February 2011, extensive ground cracking in loessial soils was reported in some areas of the Port Hills, southeast of central Christchurch. This study was undertaken to investigate the mechanisms of earthquake-induced ground damage on the eastern side of the Hillsborough Valley. A zone of extensional cracking up to 40m wide and 600m long was identified along the eastern foot-slope, accompanied by compression features and spring formation at the toe of the slope. An engineering geological and geomorphological model was developed for the eastern Hillsborough Valley that incorporates geotechnical investigation data sourced from the Canterbury Geotechnical Database (CGD), the findings of trenching and seismic refraction surveying carried out for this research, and interpretation of historical aerial photographs. The thickness and extent of a buried peat swamp at the base of the slope was mapped, and found to coincide with significant compression features. Ground cracking was found to have occurred entirely within loess-colluvium and to follow the apices of pre-1920s tunnel-gully fan debris at the southern end of the valley. The ground-cracking on the eastern side of the Hillsborough Valley is interpreted to have formed through tensile failure of the loess-colluvium. Testing was carried out to determine the tensile strength of Port Hills loess colluvium as a function of water content and density, in order to better understand the occurrence and distribution of the observed ground cracking. A comprehensive review of the soil tensile strength testing literature was undertaken, from which a test methodology was developed. Results show remoulded loess-colluvium to possess tensile strength of 7 - 28 kPa across the range of tested moisture contents (10-15%) and dry densities (1650-1900kg/m3). A positive linear relationship was observed between tensile strength and dry density, and a negative linear relationship between moisture content and tensile strength. The observed ground damage and available geotechnical information (inclinometer and piezometer records provided by the Earthquake Commission) were together used to interpret the mechanism(s) of slope movement that occurred in the eastern Hillsborough Valley. The observed ground damage is characteristic of translational movement, but without the development of lateral release scarps, or a basal sliding surface - which was not located during drilling. It is hypothesised that shear displacement has been accommodated by multiple slip surfaces of limited extent within the upper 10m of the slope. Movement has likely occurred within near-saturated colluvial units that have lost strength during earthquake shaking. The eastern Hillsborough Valley is considered to be an ‘incipient translational slide’, as both the patterns of damage and shearing are consistent with the early stages of such slide development. Sliding block analysis was utilised to understand how the eastern Hillsborough Valley may perform in a future large magnitude earthquake. Known cumulative displacements of ~0.3m for eastern Hillsborough Valley during the 2010-2011 Canterbury Earthquake Sequence were compared with modelled slope displacements to back-analyse a lower-bound yield acceleration of 0.2 - 0.25g. Synthetic broadband modelling for future Alpine and Hope Fault earthquakes indicates PGAs of approximately 0.08g for soil sites in the Christchurch area, as such, slope movement is unlikely to be reactivated by an Alpine Fault or Hope Fault earthquake. This does not take into account the possible role of strength loss due to excess pore pressure that may occur during these future events.
As a result of the 4 September 2010 Darfield earthquake and the more damaging 22 February 2011 Christchurch earthquake, considerable damage occurred to a significant number of buildings in Christchurch. The damage that occurred to the Christchurch Roman Catholic Cathedral of the Blessed Sacrament (commonly known as the Christchurch Basilica) as a result of the Canterbury earthquakes is reported, and the observed failure modes are identified. A previous strengthening intervention is outlined and the estimated capacity of the building is discussed. This strengthening was completed in 2004, and addressed the worst aspects of the building's seismic vulnerability. Urgent work was undertaken post-earthquake to secure parts of the building in order to limit damage and prevent collapse of unstable parts of the building. The approach taken for this securing is outlined, and the performance of the building and the previously installed earthquake strengthening intervention is evaluated.A key consideration throughout the project was the interaction between the structural securing requirements that were driven by the requirement to limit damage and mitigate hazards, and the heritage considerations. Lessons learnt from the strengthening that was carried out, the securing work undertaken, and the approach taken in making the building "safe" are discussed. Some conclusions are drawn with respect to the effectiveness of strengthening similar building types, and the approach taken to secure the building under active seismic conditions. AM - Accepted Manuscript
Following the 2010/2011 Canterbury earthquakes a detailed campaign of door to door assessments was conducted in a variety of areas of Christchurch to establish the earthquake performance of residential dwellings having masonry veneer as an external cladding attached to a lightweight timber framing system. Specifically, care was taken to include regions of Christchurch which experienced different levels of earthquake shaking in order to allow comparison between the performance of different systems and different shaking intensities. At the time of the inspections the buildings in the Christchurch region had been repeatedly subjected to large earthquakes, presenting an opportunity for insight into the seismic performance of masonry veneer cladding. In total just under 1100 residential dwellings were inspected throughout the wider Christchurch area, of which 24% were constructed using the older nail-on veneer tie system (prior to 1996) and 76% were constructed using screw fixed ties to comply with the new 1996 standards revision (post-1996), with 30% of all inspected houses being of two storey construction. Of the inspected dwellings 27% had some evidence of liquefaction, ground settlement or lateral spreading. Data such as damage level, damage type, crack widths, level of repair required and other parameters were collected during the survey. A description of the data collection processes and a snapshot of the analysis results are presented within. http://15ibmac.com/home/
This study explores the impact post-earthquake images from Christchurch, New Zealand inserted into a task requiring sustained attention or vigilance have on performance, selfreports of task-focus, and cerebra activity using functional near-infrared spectroscopy (fNIRS). The images represent the current state of Christchurch; a city struggling to recover from devastating earthquakes that peaked in February, 2011, killing 185 people, injuring hundreds more and causing widespread and massive damage to infrastructure, land and building in the region. Crowdsourcing was used to gather a series of positive and negative photos from greater Christchurch to be employed in the subsequent experiment. Seventy-one Christchurch resident participants (51 women, 20 men) then took part in a vigilance task with the sourced images embedded to assess possible cognitive disruptions. Participants were randomly assigned to one of three conditions: embedded positive pictures, embedded negative pictures, or embedded scrambled image controls. Task performance was assessed with signal detection theory metrics of sensitivity A’ and β’’. Individuals viewing the positive images, relating to progress, rebuild, or aesthetic aspects within the city, were overall more conservative or less willing to respond than those in the other conditions. In addition, positive condition individuals reported lower task focus, when compared to those in the control condition. However, indicators of cerebral activity (fNIRS) did not differ significantly between the experimental groups. These results combined, suggest that mind wandering events may be being generated when exposed to positive post-earthquake images. This finding fits with recent research which indicates that mind-wandering or day dreaming tends to be positive and future oriented. While positive recovery images may initiate internal thoughts, this could actually prove problematic in contexts in which external attention is required. While the actual environment, of course, needs to recover, support agencies may want to be careful with employing positive recovery imagery in contexts where people actually should be paying attention to something else, like operating a vehicle or machinery.
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A magnitude 6.3 earthquake struck the city of Christchurch at 12:51pm on Tuesday 22 February 2011. The earthquake caused 182 fatalities, a large number of injuries, and resulted in widespread damage to the built environment, including significant disruption to the lifelines. The event created the largest lifeline disruption in a New Zealand city in 80 years, with much of the damage resulting from extensive and severe liquefaction in the Christchurch urban area. The Christchurch earthquake occurred when the Canterbury region and its lifelines systems were at the early stage of recovering from the 4 September 2010 Darfield (Canterbury) magnitude 7.1 earthquake. This paper describes the impact of the Christchurch earthquake on lifelines by briefly summarising the physical damage to the networks, the system performance and the operational response during the emergency management and the recovery phase. Special focus is given to the performance and management of the gas, electric and road networks and to the liquefaction ejecta clean-up operations that contributed to the rapid reinstatement of the functionality of many of the lifelines. The water and wastewater system performances are also summarized. Elements of resilience that contributed to good network performance or to efficient emergency and recovery management are highlighted in the paper.
The Canterbury region experienced widespread damage due to liquefaction induced by seismic shaking during the 4 September 2010 earthquake and the large aftershocks that followed, notably those that occurred on 22 February, 13 June and 23 December 2011. Following the 2010 earthquake, the Earthquake Commission directed a thorough investigation of the ground profile in Christchurch, and to date, more than 7500 cone penetration tests (CPT) have been performed in the region. This paper presents the results of analyses which use a subset of the geotechnical database to evaluate the liquefaction process as well as the re-liquefaction that occurred following some of the major events in Christchurch. First, the applicability of existing CPT-based methods for evaluating liquefaction potential of Christchurch soils was investigated using three methods currently available. Next, the results of liquefaction potential evaluation were compared with the severity of observed damage, categorised in terms of the land damage grade developed from Tonkin & Taylor property inspections as well as from observed severity of liquefaction from aerial photography. For this purpose, the Liquefaction Potential Index (LPI) was used to represent the damage potential at each site. In addition, a comparison of the CPT-based strength profiles obtained before each of the major aftershocks was performed. The results suggest that the analysis of spatial and temporal variations of strength profiles gives a clear indication of the resulting liquefaction and re-liquefaction observed in Christchurch. The comparison of a limited number of CPT strength profiles before and after the earthquakes seems to indicate that no noticeable strengthening has occurred in Christchurch, making the area vulnerable to liquefaction induced land damage in future large-scale earthquakes.
Individual responses to natural disasters are highly variable. The psychological and behavioural response trajectories of those who manage to cope well with adverse life events are in need of further investigation. Increased alcohol use is often observed in communities exposed to mass traumas, particularly among those exposed to severe levels of trauma, with males drinking more than females. The current study examined patterns of alcohol use and motivations for drinking among a sample of psychologically resilient individuals with varying levels of exposure to the Canterbury earthquakes (N = 91) using structured and semi-structured interviews and self-report measures. As hypothesised, there was a significant increase in alcohol consumption since the earthquakes began, and males reported significantly higher levels of pre-earthquake and current alcohol consumption than females. Contrary to expectations, there was no association between traumatic exposure severity and alcohol consumption. While participants reported anxiety-based coping motives for drinking at levels comparable to those reported by other studies, depression-based coping motives were significantly lower, providing partial support for the hypothesis that participants would report coping motives for drinking at levels comparable to those found by other researchers. No gender differences in drinking motives were found. As expected, current alcohol consumption was positively correlated with anxiety and depression-based coping motives for drinking. Psychological resilience was not significantly associated with alcohol use, however resilience was negatively associated with depression-based coping motives for drinking. These findings have inter-generational and international implications for post-traumatic intervention.
Following the magnitude 6.3 aftershock in Christchurch, New Zealand, on 22 February 2011, a number of researchers were sent to Christchurch as part of the New Zealand Natural Hazard Research Platform funded “Project Masonry” Recovery Project. Their goal was to document and interpret the damage to the masonry buildings and churches in the region. Approximately 650 unreinforced and retrofitted clay brick masonry buildings in the Christchurch area were surveyed for commonly occurring failure patterns and collapse mechanisms. The entire building stock of Christchurch, and in particular the unreinforced masonry building stock, is similar to that in the rest of New Zealand, Australia, and abroad, so the observations made here are relevant for the entire world.
On 14 November 2016, the Mw 7.8 Kaikōura earthquake caused widespread damage along the east coast of the South Island, New Zealand. Kaikōura town itself was isolated from the rest of the country by landslides blocking off major roads. While impacts from the Kaikōura earthquake on large, urban population centres have been generally well documented, this thesis aims to fill gaps in academic knowledge regarding small rural towns. This thesis investigates what, where and when critical infrastructure and lifeline service disruption occurred following the 2016 Kaikōura earthquake in a selection of small towns, and how the communities in these areas adapted to disruption. Following a robust review of literature and news media, four small rural towns were selected from North Canterbury (Culverden & Waiau) and Marlborough (Seddon & Ward) in the South Island, New Zealand. Semi-structured interview sessions with a special focus on these towns were held with infrastructure managers, emergency response and recovery officials, and organisation leaders with experience or expertise in the 2016 Kaikōura earthquake. Findings were supplemented with emergency management situation reports to produce hazard maps and infrastructure exposure maps. A more detailed analysis was conducted for Waiau involving interdependence analyses and a level of service timeline for select lifeline services. The earthquake impacted roads by blocking them with landslides, debris and surface rupture. Bridges where shaken off their abutments, breaking infrastructure links such as fibre landlines as they went. Water supplies and other forms of infrastructure relied heavily on the level of service of roads, as rough rural terrain left few alternatives. Adapting to an artificial loss of road service, some Waiau locals created their own detour around a road cordon in order to get home to family and farms. Performance of dwellings was tied to socioeconomic factors as much as proximity to the epicentre. Farmers who lost water access pulled out fences to allow stock to drink from rivers. Socioeconomic differences between farmland and township residents also contributed to resilience variations between the towns assessed in this study. Understanding how small rural towns respond and adapt to disaster allows emergency management officials and policy to be well informed and flexible with planning for multiple size classes of towns.
Though rare and unpredictable, earthquakes can and do cause catastrophic destruction when they impact unprepared and vulnerable communities. Extensive damage and failure of vulnerable buildings is a key factor which contributes to seismic-related disasters, making the proactive management of these buildings a necessity to reduce the risk of future disasters arising. The devastating Canterbury earthquakes of 2010 and 2011 brought the urgency of this issue to national importance in New Zealand. The national earthquake-prone building framework came into effect in 2017, obligating authorities to identify existing buildings with the greatest risk of collapse in strong earthquakes and for building owners to strengthen or demolish these buildings within a designated period of time. Though this framework is unique to New Zealand, the challenge of managing the seismic risk of such buildings is common amongst all seismically-active countries. Therefore, looking outward to examine how other jurisdictions legally manage this challenge is useful for reflecting on the approaches taken in New Zealand and understand potential lessons which could be adopted. This research compares the legal framework used to reduce the seismic risk of existing buildings in New Zealand with that of the similarly earthquake-prone countries of Japan and Italy. These legal frameworks are examined with a particular focus on the proactive goal of reducing risk and improving resilience, as is the goal of the international Sendai Framework for Disaster Risk Reduction 2015-2030. The Sendai Framework, which each of the case study countries have committed to and thus have obligations under, forms the legal basis of the need for states to reduce disaster risk in their jurisdictions. In particular, the states’ legal frameworks for existing building risk reduction are examined in the context of the Sendai priorities of understanding disaster risk, strengthening disaster risk governance, and investing in resilience. While this research illustrates that the case study countries have each adopted more proactive risk reduction frameworks in recent years in anticipation of future earthquakes, the frameworks currently focus on a very narrow range of existing buildings and thus are not currently sufficient for promoting the long-term resilience of building stocks. In order to improve resilience, it is argued, legal frameworks need to include a broader range of buildings subject to seismic risk reduction obligations and also to broaden the focus on long-term monitoring of potential risk to buildings.
Recently developed performance-based earthquake engineering framework, such as one provided by PEER (Deierlein et al. 2003), assist in the quantification in terms of performance such as casualty, monetary losses and downtime. This opens up the opportunity to identify cost-effective retrofit/rehabilitation strategies by comparing upfront costs associated with retrofit with the repair costs that can be expected over time. This loss assessment can be strengthened by learning from recent earthquakes, such as the 2010 Canterbury and 2016 Kaikoura earthquakes. In order to investigate which types of retrofit/rehabilitation strategies may be most cost-effective, a case study building was chosen for this research. The Pacific Tower, a 22-storey EBF apartment located within the Christchurch central business district (CBD), was damaged and repaired during the 2010 Canterbury earthquake series. As such, by taking hazard levels accordingly (i.e. to correspond to the Christchurch CBD), modelling and analysing the structure, and considering the vulnerability and repair costs of its different components, it is possible to predict the expected losses of the aforementioned building. Using this information, cost-effective retrofit/rehabilitation strategy can be determined. This research found that more often than not, it would be beneficial to improve the performance of valuable non-structural components, such as partitions. Although it is true that improving such elements will increase the initial costs, over time, the benefits gained from reduced losses should be expected to overcome the initial costs. Aftershocks do increase the predicted losses of a building even in lower intensities due to the fact that non-structural components can get damaged at such low intensities. By comparing losses computed with and without consideration of aftershocks for a range of historical earthquakes, it was found that the ratio between losses due to main shock with aftershocks to the losses due to the main shock only tended to increase with increasing main shock magnitude. This may be due to the fact that larger magnitude earthquakes tend to generate larger magnitude aftershocks and as those aftershocks happen within a region around the main shock, they are more likely to cause intense shaking and additional damage. In addition to this observation, it was observed that the most significant component of loss of the case study building was the non-structural partition walls.
The progressive damage and subsequent demolition of unreinforced masonry (URM) buildings arising from the Canterbury earthquake sequence is reported. A dataset was compiled of all URM buildings located within the Christchurch CBD, including information on location, building characteristics, and damage levels after each major earthquake in this sequence. A general description of the overall damage and the hazard to both building occupants and to nearby pedestrians due to debris falling from URM buildings is presented with several case study buildings used to describe the accumulation of damage over the earthquake sequence. The benefit of seismic improvement techniques that had been installed to URM buildings is shown by the reduced damage ratios reported for increased levels of retrofit. Demolition statistics for URM buildings in the Christchurch CBD are also reported and discussed. VoR - Version of Record
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The latest two great earthquake sequences; 2010- 2011 Canterbury Earthquake and 2016 Kaikoura Earthquake, necessitate a better understanding of the New Zealand seismic hazard condition for new building design and detailed assessment of existing buildings. It is important to note, however, that the New Zealand seismic hazard map in NZS 1170.5.2004 is generalised in effort to cover all of New Zealand and limited to a earthquake database prior to 2001. This is “common” that site-specific studies typically provide spectral accelerations different to those shown on the national map (Z values in NZS 1170.5:2004); and sometimes even lower. Moreover, Section 5.2 of Module 1 of the Earthquake Geotechnical Engineering Practice series provide the guidelines to perform site- specific studies.
The abundance of cone penetration test (CPT) data from subsurface explorations in Christchurch and the surrounding areas provides a useful source of information for a characterization of the near surface shear wave velocity ( ) profile for the region. A portion of the investigations were conducted using seismic CPT, enabling the comparison of measured shear wave velocity with CPT data, and subsequently the evaluation of existing CPT- correlations for applicability to Canterbury-specific soils. The existing correlations are shown to be biased, generally over-predicting the observed with depth, thus demonstrating the need for a Canterbury-specific CPT- correlation.
