The structure and geomorphology of active orogens evolves on time scales ranging from a single earthquake to millions of years of tectonic deformation. Analysis of crustal deformation using new and established remote sensing techniques, and integration of these data with field mapping, geochronology and the sedimentary record, create new opportunities to understand orogenic evolution over these timescales. Timor Leste (East Timor) lies on the northern collisional boundary between continental crust from the Australian Plate and the Banda volcanic arc. GPS studies have indicated that the island of Timor is actively shortening. Field mapping and fault kinematic analysis of an emergent Pliocene marine sequence identifies gentle folding, overprinted by a predominance of NW-SE oriented dextral-normal faults and NE-SW oriented sinistral-normal faults that collectively bound large (5-20km2) bedrock massifs throughout the island. These fault systems intersect at non-Andersonian conjugate angles of approximately 120° and accommodate an estimated 20 km of orogen-parallel extension. Folding of Pliocene rocks in Timor may represent an early episode of contraction but the overall pattern of deformation is one of lateral crustal extrusion sub-parallel to the Banda Arc. Stratigraphic relationships suggest that extrusion began prior to 5.5 Ma, during and after initial uplift of the orogen. Sedimentological, geochemical and Nd isotope data indicate that the island of Timor was emergent and shedding terrigenous sediment into carbonate basins prior to 4.5 Ma. Synorogenic tectonic and sedimentary phases initiated almost synchronously across much of Timor Leste and <2 Myr before similar events in West Timor. An increase in plate coupling along this obliquely converging boundary, due to subduction of an outlying continental plateau at the Banda Trench, is proposed as a mechanism for uplift that accounts for orogen-parallel extension and early uplift of Timor Leste. Rapid bathymetric changes around Timor are likely to have played an important role in evolution of the Indonesian Seaway. The 2010 Mw 7.1 Darfield (Canterbury) earthquake in New Zealand was complex, involving multiple faults with strike-slip, reverse and normal displacements. Multi-temporal cadastral surveying and airborne light detection and ranging (LiDAR) surveys allowed surface deformation at the junction of three faults to be analyzed in this study in unprecedented detail. A nested, localized restraining stepover with contractional bulging was identified in an area with the overall fault structure of a releasing bend, highlighting the surface complexities that may develop in fault interaction zones during a single earthquake sequence. The earthquake also caused river avulsion and flooding in this area. Geomorphic investigations of these rivers prior to the earthquake identify plausible precursory patterns, including channel migration and narrowing. Comparison of the pre and post-earthquake geomorphology of the fault rupture also suggests that a subtle scarp or groove was present along much of the trace prior to the Darfield earthquake. Hydrogeology and well logs support a hypothesis of extended slip history and suggests that that the Selwyn River fan may be infilling a graben that has accumulated late Quaternary vertical slip of <30 m. Investigating fault behavior, geomorphic and sedimentary responses over a multitude of time-scales and at different study sites provides insights into fault interactions and orogenesis during single earthquakes and over millions of years of plate boundary deformation.
Soil-structure interaction (SSI) has been widely studied during the last decades. The influence of the properties of the ground motion, the structure and the soil have been addressed. However, most of the studies in this field consider a stand-alone structure. This assumption is rarely justifiable in dense urban areas where structures are built close to one another. The dynamic interaction between adjacent structures has been studied since the early 1970s, mainly using numerical and analytical models. Even though the early works in this field have significantly contributed to understanding this problem, they commonly consider important simplifications such as assuming a linear behaviour of the structure and the soil. Some experimental works addressing adjacent structures have recently been conducted using geotechnical centrifuges and 1g shake tables. However, further research is needed to enhance the understanding of this complex phenomenon. A particular case of SSI is that of structures founded in fine loose saturated sandy soil. An iconic example was the devastating effects of liquefaction in Christchurch, New Zealand, during the Canterbury earthquake in 2011. In the case of adjacent structures on liquefiable soil, the experimental evidence is even scarcer. The present work addresses the dynamic interaction between adjacent structures by performing multiple experimental studies. The work starts with two-adjacent structures on a small soil container to expose the basics of the problem. Later, results from tests considering a more significant number of structures on a big laminar box filled with sand are presented. Finally, the response of adjacent structures on saturated sandy soil is addressed using a geotechnical centrifuge and a large 1g shake table. This research shows that the acceleration, lateral displacement, foundation rocking, damping ratio, and fundamental frequency of the structure of focus are considerably affected by the presence of neighbouring buildings. In general, adjacent buildings reduced the dynamic response of the structure of focus on dry sand. However, the acceleration was amplified when the structures had a similar fundamental frequency. In the case of structures on saturated sand, the presence of adjacent structures reduced the liquefaction potential. Neighbouring structures on saturated sand also presented larger rotation of the footing and lateral displacement of the top mass than that of the stand-alone case.
Depending on their nature and severity, disasters can create large volumes of debris and waste. Waste volumes from a single event can be the equivalent of many times the annual waste generation rate of the affected community. These volumes can overwhelm existing solid waste management facilities and personnel. Mismanagement of disaster waste can affect both the response and long term recovery of a disaster affected area. Previous research into disaster waste management has been either context specific or event specific, making it difficult to transfer lessons from one disaster event to another. The aim of this research is to develop a systems understanding of disaster waste management and in turn develop context- and disaster-transferrable decision-making guidance for emergency and waste managers. To research this complex and multi-disciplinary problem, a multi-hazard, multi-context, multi-case study approach was adopted. The research focussed on five major disaster events: 2011 Christchurch earthquake, 2009 Victorian Bushfires, 2009 Samoan tsunami, 2009 L’Aquila earthquake and 2005 Hurricane Katrina. The first stage of the analysis involved the development of a set of ‘disaster & disaster waste’ impact indicators. The indicators demonstrate a method by which disaster managers, planners and researchers can simplify the very large spectra of possible disaster impacts, into some key decision-drivers which will likely influence post-disaster management requirements. The second stage of the research was to develop a set of criteria to represent the desirable environmental, economic, social and recovery effects of a successful disaster waste management system. These criteria were used to assess the effectiveness of the disaster waste management approaches for the case studies. The third stage of the research was the cross-case analysis. Six main elements of disaster waste management systems were identified and analysed. These were: strategic management, funding mechanisms, operational management, environmental and human health risk management, and legislation and regulation. Within each of these system elements, key decision-making guidance (linked to the ‘disaster & disaster waste’ indicators) and management principles were developed. The ‘disaster & disaster waste’ impact indicators, the effects assessment criteria and management principles have all been developed so that they can be practically applied to disaster waste management planning and response in the future.
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 extent of liquefaction in the eastern suburbs of Christchurch (Aranui, Bexley, Avonside, Avonhead and Dallington) from the February 22 2011 Earthquake resulted in extensive damage to in-ground waste water pipe systems. This caused a huge demand for portable toilets (or port-a-loos) and companies were importing them from outside Canterbury and in some instances from Australia. However, because they were deemed “assets of importance” under legislation, their allocation had to be coordinated by Civil Defence and Emergency Management (CDEM). Consequently, companies supplying them had to ignore requests from residents, businesses and rest homes; and commitments to large events outside of the city such as the Hamilton 400 V8 Supercars and the Pasifika Festival in Auckland were impacted. Frustrations started to show as neighbourhoods questioned the equity of the port-a-loos distribution. The Prime Minister was reported as reassuring citizens in the eastern suburbs in the first week of March that1 “a report about the distribution of port-a-loos and chemical toilets shows allocation has been fair. Key said he has asked Civil Defence about the distribution process and where the toilets been sent. He said there aren’t enough for the scale of the event but that is quickly being rectified and the need for toilets is being reassessed all the time.” Nonetheless, there still remained a deep sense of frustration and exclusion over the equity of the port-a-loos distribution. This study took the simple approach of mapping where those port-a-loos were on 11-12 March for several areas in the eastern suburbs and this suggested that their distribution was not equitable and was not well done. It reviews the predictive tools available for estimating damage to waste water pipes and asks the question could this situation have been better planned so that pot-a-loo locations could have been better prioritised? And finally it reviews the integral roles of communication and monitoring as part of disaster management strategy. The impression from this study is that other New Zealand urban centres could or would also be at risk and that work is need to developed more rational management approaches for disaster planning.
The effects of soil-foundation-structure interaction (SFSI) have been a topic of discussion amongst the structural and geotechnical community for many decades. The complexity of the mechanisms, as well as the need for inter-disciplinary knowledge of geotechnical and structural dynamics has plagued the advancement and the consequent inclusion of SFSI effects in design. A rigorous performance-based design methodology should not just consider the performance of the superstructure but the supporting foundation system as well. Case studies throughout history (eg. Kobe 1995, Kocaeli 1999 and Christchurch earthquakes 2010-2011) have demonstrated that a poor performance at the foundation level can result in a full demolition of the structure and, in general terms, that the extent of damage to, and repairability of, the building system as a whole, is given by the combination of the damage to the soil, foundation and superstructure. The lack of consideration of the modifying factors of SFSI and an absence of intuitive performance levels for controlling foundation and soil behaviour under seismic loads has resulted in inadequate designs for buildings sited on soft soil. For engineers to be satisfied that their designs meet the given performance levels they must first, understand how SFSI affects the overall system performance and secondly have tools available to adequately account for it in their design/assessment. This dissertation presents an integrated performance-based design procedure for buildingfoundation systems that considers all of the major mechanisms of SFSI. A new soil-foundation macro-element model was implemented into a nonlinear finite element software and validated against several experimental tests. The numerical model was used to provide insights in to the mechanisms of SFSI and statistical analysis on the results yielded simple expressions that allow the behaviour to be quantified. Particular attention was paid to the effects of shear force on the foundation response and the quantification of the rocking mode of response. The residual deformations of the superstructure and distribution of forces up the structure were also investigated. All of the major SFSI mechanisms are discussed in detail and targeted numerical studies are used to explain and demonstrate concepts. The design procedure was validated through the design and assessment of a series of concrete buildings that were designed to account for the effects of SFSI.
The Stone Jug Fault (SJF) ruptured during the November 14th, 2016 (at 12:02 am), Mw 7.8 Kaikōura Earthquake which initiated ~40 km west-southwest of the study area, at a depth of approximately 15 km. Preliminary post-earthquake mapping indicated that the SJF connects the Conway-Charwell and Hundalee faults, which form continuous surface rupture, however, detailed study of the SJF had not been undertaken prior to this thesis due to its remote location and mountainous topography. The SJF is 19 km long, has an average strike of ~160° and generally carries approximately equal components of sinistral and reverse displacement. The primary fault trace is sigmoidal in shape with the northern and southern tips rotating in strike from NNW to NW, as the SJF approaches the Hope and Hundalee faults. It comprises several steps and bends and is associated with many (N=48) secondary faults, which are commonly near irregularities in the main fault geometry and in a distributed fault zone at the southern tip. The SJF is generally parallel to Torlesse basement bedding where it may utilise pre-existing zones of weakness. Horizontal, vertical and net displacements range up to 1.4 m, with displacement profiles along the primary trace showing two main maxima separated by a minima towards the middle and ends of the fault. Average net displacement along the primary trace is ~0.4m, with local changes in relative values of horizontal and vertical displacement at least partly controlled by fault strike. Two trenches excavated across the northern segment of the fault revealed displacement of mainly Holocene stratigraphy dated using radiocarbon (N=2) and OSL (N=4) samples. Five surface-rupturing paleoearthquakes displaying vertical displacements of <1 m occurred at: 11,000±1000, 7500±1000, 6500±1000, 3500±100 and 3 (2016 Kaikōura) years BP. These events produce an average slip rate since ~11 ka of 0.2-0.4 mm/yr and recurrence intervals of up to 5500 years with an average recurrence interval of 2750 yrs. Comparison of these results with unpublished trench data suggests that synchronous rupture of the Hundalee, Stone Jug, Conway-Charwell, and Humps faults at ~3500 yrs BP cannot be discounted and it is possible that multi-fault ruptures in north Canterbury are more common than previously thought.
Post-tensioned timber technology was originally developed and researched at the University of Canterbury (UC) in New Zealand in 2005. It can provide a low-damage seismic design solution for multi-storey mass timber buildings. Since mass timber products, such as cross-laminated timber (CLT), have high in-plane stiffness, a post-tensioned timber shear wall will deform mainly in a rocking mechanism. The moment capacity of the wall at the base is commonly determined using the elastic form of the Modified Monolithic Beam Analogy (MMBA). In the calculation of the moment capacity at the wall base, it is critical to accurately predict the location of the neutral axis and the timber compressive stress distribution. Three 2/3 scale 8.6m tall post-tensioned CLT walls were experimentally tested under quasi-static cyclic loading – both uni-directional and bi-directional- in this study. These specimens included a single wall, a coupled wall, and a C-shaped core-wall. The main objective was to develop post-tensioned C-shaped timber core-walls for tall timber buildings with enhanced lateral strength and stiffness. To better understand the timber compressive stress distributions at the wall base, particle tracking technology (PTT) technology was applied for the first time to investigate the behaviour of the compression toe. Previous post-tensioned timber testing primarily used the displacement measurements to determine the timber compressive behavior at the wall base or rocking interfaces. However, by using PTT technology, the timber strain measurements in the compression zone can be much more accurate as PTT is able to track the movement of many particles on the timber surface. This paper presents experimental testing results of post-tensioned CLT walls with a focus on capturing timber compressive behavior using PTT. The PTT measurements were able to better capture small base rotations which occurred at the onset of gap opening and capture unexpected phenomena in core-wall tests. The single wall test result herein presented indicates that while the MMBA could predict the moment rotation behavior with reasonable accuracy, the peak strain response was under predicted in the compression toe. Further detailed study is required to better understand the complex strain fields generated reflective of the inherent cross-thickness inhomogeneity and material variability of CLT.
Researchers have begun to explore the opportunity presented by blue-green infrastructure(a subset of nature-based solutions that provide blue and green space in urban infrastructure)as a response to the pressures of climate change. The 2010/2011 Canterbury earthquake sequence created a unique landscape within which there is opportunity to experiment with and invest in new solutions to climate change adaptation in urban centres. Constructed wetlands are an example of blue-green infrastructure that can potentially support resilience in urban communities. This research explores interactions between communities and constructed wetlands to understand how this may influence perceptions of community resilience. The regeneration of the Ōtākaro Avon River Corridor (OARC) provides a space to investigate these relationships. Seven stakeholders from the community, industry, and academia, each with experience in blue-green infrastructure in the OARC, participated in a series of semi-structured interviews. Each participant was given the opportunity to reflect on their perspectives of community, community resilience, and constructed wetlands and their interconnections. Interview questions aligned with the overarching research objectives to (1) understand perceptions around the role of wetlands in urban communities, (2) develop a definition for community resilience in the context of the Ōtākaro Avon community, and (3) reflect on how wetlands can contribute to (or detract from) community resilience. This study found that constructed wetlands can facilitate learning about the challenges and solutions needed to adapt to climate change. From the perspective of the community representatives, community resilience is linked to social capital. Strong social networks and a relationship with nature were emphasised as core components of a community’s ability to adapt to disruption. Constructed wetlands are therefore recognised as potentially contributing to community resilience by providing spaces for people to engage with each other and nature. Investment in constructed wetlands can support a wider response to climate change impacts. This research was undertaken with the support of the Ōtākaro Living Laboratory Trust, who are invested in the future of the OARC. The outcomes of this study suggest that there is an opportunity to use wetland spaces to establish programmes that explore the perceptions of constructed wetlands from a broader community definition, at each stage of the wetland life cycle, and at wider scales(e.g., at a city scale or beyond).
The role of belonging in post-disaster environments remains an under-theorised concept, particularly regarding refugee populations. This paper presents a qualitative study with 101 refugee-background participants from varying communities living in Christchurch, New Zealand, about their perspectives and responses to the Canterbury earthquakes of 2010–11. Participants spoke of how a sense of belonging as individuals and as a wider community was important in the recovery effort, and highlighted the multiple ways in which they understood this concept. Their comments demonstrate how belonging can have contextual, chronological and gendered dimensions that can help inform effective and resonant disaster responses with culturally and linguistically diverse populations. This analysis also illustrates how the participants' perspectives of belonging shifted over time, and discusses the corresponding role of social work in supporting post-disaster recovery through the concepts of civic, ethno and ethnic-based belonging. AM - Accepted Manuscript
During the Christchurch earthquake of February 2011, several midrise reinforced concrete masonry (RCM) buildings showed performance levels that fall in the range of life safety to near collapse. A case study of one of these buildings, a six-story RCM building deemed to have reached the near collapse performance level, is presented in this paper. The RCM walls on the second floor failed due to toe crushing, reducing the building's lateral resistance in the east–west direction. A three-dimensional (3-D) nonlinear dynamic analysis was conducted to simulate the development of the governing failure mechanism. Analysis results showed that the walls that were damaged were subjected to large compression loads during the earthquake, which caused an increase in their in-plane lateral strength but reduced their ductility capacity. After toe crushing failure, axial instability of the model was prevented by a redistribution of gravity loads. VoR - Version of Record
A major lesson from the 2011 Christchurch earthquake was the apparent lack of ductility of some lightly reinforced concrete (RC) wall structures. In particular, the structural behaviour of the critical wall in the Gallery Apartments building demonstrated that the inelastic deformation capacity of a structure, as well as potentially brittle failure of the reinforcement, is dependent on the level of bond deterioration between reinforcement and surrounding concrete that occurs under seismic loading. This paper presents the findings of an experimental study on bond behaviour between deformed reinforcing bars and the surrounding concrete. Bond strength and relative bond slip was evaluated using 75 pull-out tests under monotonic and cyclic loading. Variations of the experiments include the loading rate, loading history, concrete strength (25 to 70 MPa), concrete age, cover thickness, bar diameter (16 and 20 mm), embedded length, and the position of the embedded bond region within the specimen (deep within or close to free surface). Select test results are presented with inferred implications for RC structures.
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.
This paper presents an examination of ground motion observations from 20 near-source strong motion stations during the most significant 10 events in the 2010-2011 Canterbury earthquake to examine region-specific systematic effects based on relaxing the conventional ergodic assumption. On the basis of similar site-to-site residuals, surfical geology, and geographical proximity, 15 of the 20 stations are grouped into four sub-regions: the Central Business District; and Western, Eastern, and Northern suburbs. Mean site-to-site residuals for these sub-regions then allows for the possibility of non-ergodic ground motion prediction over these sub-regions of Canterbury, rather than only at strong motion station locations. The ratio of the total non-ergodic vs. ergodic standard deviation is found to be, on average, consistent with previous studies, however it is emphasized that on a site-by-site basis the non-ergodic standard deviation can easily vary by ±20%.
This study investigates the uncertainty of simulated earthquake ground motions for smallmagnitude events (Mw 3.5 – 5) in Canterbury, New Zealand. 148 events were simulated with specified uncertainties in: event magnitude, hypocentre location, focal mechanism, high frequency rupture velocity, Brune stress parameter, the site 30-m time-averaged shear wave velocity (Vs30), anelastic attenuation (Q) and high frequency path duration. In order to capture these uncertainties, 25 realisations for each event were generated using the Graves and Pitarka (2015) hybrid broadband simulation approach. Monte-Carlo realisations were drawn from distributions for each uncertainty, to generate a suite of simulation realisations for each event and site. The fit of the multiple simulation realisations to observations were assessed using linear mixed effects regression to generate the systematic source, path and site effects components across all ground motion intensity measure residuals. Findings show that additional uncertainties are required in each of the three source, path, and site components, however the level of output uncertainty is promising considering the input uncertainties included.
There is a growing awareness of the need for the earthquake engineering practice to incorporate in addition to empirical approaches in evaluation of liquefaction hazards advanced methods which can more realistically represent soil behaviour during earthquakes. Currently, this implementation is hindered by a number of challenges mainly associated with the amount of data and user-experience required for such advanced methods. In this study, we present key steps of an advanced seismic effective-stress analysis procedure, which on the one hand can be fully automated and, on the other hand, requires no additional input (at least for preliminary applications) compared to simplified cone penetration test (CPT)-based liquefaction procedures. In this way, effective-stress analysis can be routinely applied for quick, yet more robust estimations of liquefaction hazards, in a similar fashion to the simplified procedures. Important insights regarding the dynamic interactions in liquefying soils and the actual system response of a deposit can be gained from such analyses, as illustrated with the application to two sites from Christchurch, New Zealand.
One of the less understood geotechnical responses to the cyclic loading from the MW6.2 Christchurch Earthquake, on the 22nd of February 2011, is the fissuring in the loessial soil-mantled, footslope positions of the north-facing valleys of the Port Hills. The fissures are characterized by mostly horizontal offset (≤500mm), with minor vertical displacement (≤300mm), and they extend along both sides of valleys for several hundred metres in an approximately contour-parallel orientation. The fissure traces correspond to extensional features mapped in other studies. Previous studies have suggested that the fissures are the headscarps of incipient landslides, but the surface and subsurface features are not typical of landslide movement. Whilst there are some features that correlate with landslide movement, there are many features that contradict the landslide movement hypothesis. Of critical importance to this investigation was the fact that there are no landslide flanks, there has been no basal shear surface found, there is little deformation in the so-called ‘landslide body’, and there have been no recorded zones of low shear strength in the soil deposit that are indicative of a basal shear surface. This thesis is a detailed geotechnical study on the fissures along part of Ramahana Road in the Hillsborough Valley, Christchurch. Shallow and deep investigation methods found that the predominant soil is loess-colluvium, to depths of ~20m, and this soil has variable geotechnical characteristics depending on the layer sampled. The factor that has the most influence on shear strength was found to be the moisture content. Direct shear-box testing of disturbed, recompacted loess-colluvium found that the soil had a cohesion of 35-65kPa and a friction angle of 38-43° when the soil moisture content was at 8-10%. However when the moisture content was at 19-20% the soil’s cohesion decreased to 3-5kPa and its friction angle decreased to 33-38°, this moisture content is at or slightly above the plastic limit. An electrical resistivity geophysical survey was conducted perpendicular to multiple fissure traces and through the compressional zone at 17 Ramahana Road. The electrical resistivity line found that there was an area of high resistivity at the toe of the slope, and an area of high conductivity downslope of this and at greater depths. This area correlated to the compressional zone recorded by previous studies. Moisture content testing of the soil in these locations showed that the soil in the resistive area was relatively dry (9%) compared to the surrounding soil (13%), whilst the soil in the conductive area was relatively wet (22%)compared to the surrounding soil (19%). Density tests of the soil in the compressional zone recorded that the resistive area had a higher dry density than the surrounding soil (~1790 kg/m3 compared to ~1650 kg/m3). New springs arose downslope of the compressional zone contemporaneously with the fissures, and it is interpreted that these have arisen from increased hydraulic head in the Banks Peninsula bedrock aquifer system, and earthquake induced-bedrock fracturing. A test pit was dug across an infilled fissure trace at 17 Ramahana Road to a depth of 3m. The fissure trace had an aperture of 450-470mm at the ground surface, but it gradually lost aperture with depth until 2.0-2.1m where it became a segmented fissure trace with 1-2mm aperture. A mixed-colluvium layer was intercepted by the fissure trace at 2.4m depth, and there was no observable vertical offset of this layer. The fissure trace was at an angle of 78° at the ground surface, but it also flattened with depth, which gave it a slightly curved appearance. The fissure trace was at an assumed angle of 40-50° near the base of the test pit. Rotational slide, translational slide and lateral spread landslide movement types were compared and contrasted as possibilities for landslide movement types, whilst an alternative hypothesis was offered that the fissures are tensile failures with a quasi-toppling motion involving a cohesive block of loessial soil moving outwards from the slope, with an accommodating compressional strain in the lower less cohesive soil. The mechanisms behind this movement are suggested to be the horizontal earthquake inertia forces from the Christchurch Earthquake, the static shear stress of the slope, and bedrock uplift of the Port Hills in relation to the subsidence of the Christchurch city flatlands. Extremely high PGA is considered to be a prerequisite to the fissure trace development, and these can only be induced in the Hillsborough Valley from a Port Hills Fault rupture, which has a recurrence interval of ~10,000 years. The current understanding of how the loess-colluvium soil would behave under cyclic loading is limited, and the mechanisms behind the suggested movement type are not completely understood. Further research is needed to confirm the proposed mechanism of the fissure traces. Laboratory tests such as the cyclic triaxial and cyclic shear test would be beneficial in future research to quantitatively test how the soil behaves under cyclic loading at various moisture contents and clay contents, and centrifuge experiments would be of great use to qualitatively test the suggested mode of movement in the loessial soil.
The Avon-Heathcote Estuary, located in Christchurch, New Zealand, experienced coseismic deformation as a result of the February 22nd 2011 Christchurch Earthquake. The deformation is reflected as subsidence in the northern area and uplift in the southern area of the Estuary, in addition to sand volcanoes which forced up sediment throughout the floor of the Estuary altering estuary bed height and tidal flow. The first part of the research involved quantifying the change in the modern benthic foraminifera distribution as a result of the coseismic deformation caused by the February 22nd 2011 earthquake. By analysing the taxa present immediately post deformation and then the taxa present 2 years post deformation a comparison of the benthic foraminifera distribution can be made of the pre and post deformation. Both the northern and the southern areas of the Estuary were sampled to establish whether foraminifera faunas migrated landward or seaward as a result of subsidence and uplift experienced in different areas. There was no statistical change in overall species distribution in the two year time period since the coseismic deformation occurred, however, there were some noticeable changes in foraminifera distribution at BSNS-Z3 showing a landward migration of taxa. The changes that were predicted to occur as a result of the deformation of the Estuary are taking longer than expected to show up in the foraminiferal record and a longer time period is needed to establish these changes. The second stage involved establishing the modern distribution of foraminifera at Settlers Reserve in the southern area of the Avon-Heathcote Estuary by detailed sampling along a 160 m transect. Foraminifera are sensitive to environmental parameters, tidal height, grainsize, pH and salinity were recorded to evaluate the effect these parameters have on distribution. Bray-Curtis two-way cluster analysis was primarily used to assess the distribution pattern of foraminifera. The modern foraminifera distribution is comparable to that of the modern day New Zealand brackish-water benthic foraminifera distribution and includes species not yet found in other studies of the Avon-Heathcote Estuary. Differences in sampling techniques and the restricted intertidal marshland area where the transect samples were collected account for some of the differences seen between this model and past foraminifera studies. xiii The final stage involved sampling a 2.20 m core collected from Settlers Reserve and using the modern foraminiferal distribution to establish a foraminiferal history of Settlers Reserve. As foraminifera are sensitive to tidal height they may record past coseismic deformation events and the core was used to ascertain whether record of past coseismic deformation is preserved in Settlers Reserve sediments. Sampling the core for foraminifera, grainsize, trace metals and carbon material helped to build a story of estuary development. Using the modern foraminiferal distribution and the tidal height information collected, a down core model of past tidal heights was established to determine past rates of change. Foraminifera are not well preserved throughout the core, however, a sudden relative rise in sea level is recorded between 0.25 m and 0.85 m. Using trace metal and isotope analysis to develop an age profile, this sea level rise is interpreted to record coseismic subsidence associated with a palaeoseismic event in the early 1900’s. Overall, although the Avon-Heathcote Estuary experienced clear coseismic deformation as a result of the 22nd of February 2011 earthquake, modern changes in foraminiferal distribution cannot yet be tracked, however, past seismic deformation is identified in a core. The modern transect describes the foraminifera distribution which identifies species that have not been identified in the Avon-Heathcote Estuary before. This thesis enhances the current knowledge of the Avon-Heathcote Estuary and is a baseline for future studies.
The overarching goal of this dissertation is to improve predictive capabilities of geotechnical seismic site response analyses by incorporating additional salient physical phenomena that influence site effects. Specifically, multidimensional wave-propagation effects that are neglected in conventional 1D site response analyses are incorporated by: (1) combining results of 3D regional-scale simulations with 1D nonlinear wave-propagation site response analysis, and (2) modelling soil heterogeneity in 2D site response analyses using spatially-correlated random fields to perturb soil properties. A method to combine results from 3D hybrid physics-based ground motion simulations with site-specific nonlinear site response analyses was developed. The 3D simulations capture 3D ground motion phenomena on a regional scale, while the 1D nonlinear site response, which is informed by detailed site-specific soil characterization data, can capture site effects more rigorously. Simulations of 11 moderate-to-large earthquakes from the 2010-2011 Canterbury Earthquake Sequence (CES) at 20 strong motion stations (SMS) were used to validate simulations with observed ground motions. The predictions were compared to those from an empirically-based ground motion model (GMM), and from 3D simulations with simplified VS30- based site effects modelling. By comparing all predictions to observations at seismic recording stations, it was found that the 3D physics-based simulations can predict ground motions with comparable bias and uncertainty as the GMM, albeit, with significantly lower bias at long periods. Additionally, the explicit modelling of nonlinear site-response improves predictions significantly compared to the simplified VS30-based approach for soft-soil or atypical sites that exhibit exceptionally strong site effects. A method to account for the spatial variability of soils and wave scattering in 2D site response analyses was developed and validated against a database of vertical array sites in California. The inputs required to run the 2D analyses are nominally the same as those required for 1D analyses (except for spatial correlation parameters), enabling easier adoption in practice. The first step was to create the platform and workflow, and to perform a sensitivity study involving 5,400 2D model realizations to investigate the influence of random field input parameters on wave scattering and site response. Boundary conditions were carefully assessed to understand their effect on the modelled response and select appropriate assumptions for use on a 2D model with lateral heterogeneities. Multiple ground-motion intensity measures (IMs) were analyzed to quantify the influence from random field input parameters and boundary conditions. It was found that this method is capable of scattering seismic waves and creating spatially-varying ground motions at the ground surface. The redistribution of ground-motion energy across wider frequency bands, and the scattering attenuation of high-frequency waves in 2D analyses, resemble features observed in empirical transfer functions (ETFs) computed in other studies. The developed 2D method was subsequently extended to more complicated multi-layer soil profiles and applied to a database of 21 vertical array sites in California to test its appropriate- ness for future predictions. Again, different boundary condition and input motion assumptions were explored to extend the method to the in-situ conditions of a vertical array (with a sensor embedded in the soil). ETFs were compared to theoretical transfer functions (TTFs) from conventional 1D analyses and 2D analyses with heterogeneity. Residuals of transfer-function- based IMs, and IMs of surface ground motions, were also used as validation metrics. The spatial variability of transfer-function-based IMs was estimated from 2D models and compared to the event-to-event variability from ETFs. This method was found capable of significantly improving predictions of median ETF amplification factors, especially for sites that display higher event-to-event variability. For sites that are well represented by 1D methods, the 2D approach can underpredict amplification factors at higher modes, suggesting that the level of heterogeneity may be over-represented by the 2D random field models used in this study.
Landslides are significant hazards, especially in seismically-active mountainous regions, where shaking amplified by steep topography can result in widespread landsliding. These landslides present not only an acute hazard, but a chronic hazard that can last years-to-decades after the initial earthquake, causing recurring impacts. The Mw 7.8 Kaikōura earthquake caused more than 20,000 landslides throughout North Canterbury and resulted in significant damage to nationally significant infrastructure in the coastal transport corridor (CTC), isolating Kaikōura from the rest of New Zealand. In the years following, ongoing landsliding triggered by intense rainfall exacerbated the impacts and slowed the recovery process. However, while there is significant research on co-seismic landslides and their initial impacts in New Zealand, little research has explored the evolution of co-seismic landslides and how this hazard changes over time. This research maps landslides annually between 2013 and 2021 to evaluate the changes in pre-earthquake, co-seismic and post-earthquake rates of landsliding to determine how landslide hazard has changed over this time. In particular, the research explores how the number, area, and spatial distribution of landslides has changed since the earthquake, and whether post-earthquake mitigation works have in any way affected the long-term landslide hazard. Mapping of landslides was undertaken using open-source, medium resolution Landsat-8 and Sentinel-2 satellite imagery, with landslides identified visually and mapped as single polygons that capture both the source zone and deposit. Three study areas with differing levels of post-earthquake mitigation are compared: (i) the northern CTC, where the majority of mitigation was in the form of active debris removal; (ii) the southern CTC, where mitigation was primarily via passive protection measures; and (iii) Mount Fyffe, which has had no mitigation works since the earthquake. The results show that despite similar initial impacts during the earthquake, the rate of recovery in terms of landslide rates varies substantially across the three study areas. In Mount Fyffe, the number and area of landslides could take 45 and 22 years from 2021 respectively to return to pre-earthquake levels at the current rate. Comparatively, in the CTC, it could take just 5 years and 3-4 years from 2021 respectively. Notably, the fastest recovery in terms of landslide rates in the CTC was primarily located directly along the transport network, whereas what little recovery did occur in Mount Fyffe appeared to follow no particular pattern. Importantly, recovery rates in the northern CTC were notably higher than in the southern CTC, despite greater co-seismic impacts in the former. Combined, these results suggest the active, debris removal mitigation undertaken in the northern CTC may have had the effect of dramatically reducing the time for landslide rates to return to pre-earthquake levels. The role of slope angle and slope aspect were explored to evaluate if these observations could be driven by local differences in topography. The Mount Fyffe study area has higher slope angles than the CTC as a whole and landslides predominantly occurred on slightly steeper slopes than in the CTC. This may have contributed to the longer recovery times for landsliding in Mount Fyffe due to greater gravitational instability, however the observed variations are minor compared to the differences in recovery rates. In terms of slope aspect, landslides in Mount Fyffe preferentially occurred on north- and south-facing slopes whereas landslides in the CTC preferred the east- and south-facing slopes. The potential role of these differences in landslide recovery remains unclear but may be related to the propagation direction of the earthquake and the tracking direction of post-earthquake ex-tropical cyclones. Finally, landslides in the CTC are observed to be moving further away from the transport network and the number of landslides impacting the CTC decreased significantly since the earthquake. Nevertheless, the potential for further landslide reactivation remains. Therefore, despite the recovery in the CTC, it is clear that there is still risk of the transport network being impacted by further landsliding, at least for the next 3-5 yrs.
Following the 2010/2011 Canterbury earthquakes the seismic design of buildings with precast concrete panels has received significant attention. Although this form of construction generally performed adequately in Christchurch, there were a considerable number of precast concrete panel connection failures. This observation prompted a review of more than 4700 panel details from 108 buildings to establish representative details used in both existing and new multi-storey and low rise industrial precast concrete buildings in three major New Zealand cities of Auckland, Wellington and Christchurch. Details were collected from precast manufacturers and city councils and were categorised according to type. The detailing and quantity of each reviewed connection type in the sampled data is reported, and advantages and potential deficiencies of each connection type are discussed. The results of this survey provide a better understanding of the relative prevalence of common detailing used in precast concrete panels and guidance for the design of future experimental studies. http://www.nzsee.org.nz/publications/nzsee-quarterly-bulletin/
This paper presents the preliminary findings of a study on the resilience and recovery of organisations following the Darfield earthquake in New Zealand on 4 September 2010. Sampling included organisations proximal and distal to the fault trace, organisations located within central business districts, and organisations from seven diverse industry sectors. The research captured information on the challenges to, the impacts on, and the reflections of the organisations in the first months of recovery. Organisations in central business districts and in the hospitality sector were most likely to close while organisations that had perishable stock and livestock were more heavily reliant on critical services. Staff well-being, cash flow, and customer loss were major concerns for organisations across all sectors. For all organisations, the most helpful factors in mitigating the effects of the earthquake to be their relationship with staff, the design and type of buildings, and critical service continuity or swift reinstatement of services.
Well-validated liquefaction constitutive models are increasingly important as non-linear time history analyses become relatively more common in industry for key projects. Previous validation efforts of PM4Sand, a plasticity model specifically for liquefaction, have generally focused on centrifuge tests; however, pore pressure transducers installed at several free-field sites during the Canterbury Earthquake Sequence (CES) in Christchurch, New Zealand provide a relatively unique dataset to validate against. This study presents effective stress site response analyses performed in the finite difference software FLAC to examine the capability of PM4Sand to capture the generation of excess pore pressures during earthquakes. The characterization of the subsurface is primarily based on extensive cone penetration tests (CPT) carried out in Christchurch. Correlations based on penetration resistances are used to estimate soil parameters, such as relative density and shear wave velocity, which affect liquefaction behaviour. The resulting free-field FLAC model is used to estimate time histories of excess pore pressure, which are compared with records during several earthquakes in the CES to assess the suitability of PM4Sand.
There is a relationship between inelastic deformation and energy dissipation in structures that are subjected to earthquake ground motions. Thus, if seismic energy dissipation can be achieved by means of a separate non-load bearing supplementary damping system, the load bearing structure can remain elastic with continuing serviceability following the design level earthquake. This research was carried out to investigate the advantages of using added damping in structures. The control system consists of passive friction dampers called ring spring dampers installed in the ground floor of the structure using a tendon to transmit the forces to the other parts of the structure. The ring springs dampers are friction devices consisting of inner and outer ring elements assembled to form a spring stack. External load applied to the spring produces sliding action across mating ring interfaces. The damping forces generated by the dampers and transferred in the supplemental system to the structure by the tendon and horizontal links oppose the internal loads. A four storey-two bay steel frame structure was used in the study. Experimental and analytical studies to investigate the effectiveness of a supplemental control system are presented. The model was subjected to a series of earthquake simulations on the shaking table in the Structural Laboratory of the Civil Engineering Department, at the University of Canterbury. The earthquake simulation tests have been performed on the structure both with and without the supplemental control system. The earthquake simulations were a series of gradually increasing intensity replications of two commonly used earthquake records. This thesis includes detailed description of the structural model, the supplemental control system, the ring springs dampers and the data obtained during the testing. Analyses were then carried out on a twelve storey framed structure to investigate the possible tendon arrangements and the size and type of dampers required to control the response of a real building. Guidelines for determining the appropriateness of including a supplemental damping system have been investigated. The main features of the supplemental control system adopted in this research are: • It is a passive control system with extreme reliability and having no dependence on external power sources to effect the control action. These power sources may not be available during a major earthquake. • Ring springs are steel friction devices capable of absorbing large amounts of input energy. No liquid leakage can occur and minimal maintenance is required for the ring spring dampers. • With a damper-tendon system, the distribution of the dampers throughout the structure is not so critical. Only one or two dampers are used to produce the damping forces needed, and forces are then transferred to the rest of the building by the tendon system. • It is a relatively inexpensive control system with a long useful life.
The collapse of Redcliffs’ cliff in the 22 February 2011 and 13 June 2011 earthquakes were the first times ever a major failure incident occurred at Redcliffs in approximately 6000 years. This master’s thesis is a multidisciplinary engineering geological investigation sought to study these particular failure incidents, focusing on collecting the data necessary to explain the cause and effect of the cliff collapsing in the event of two major earthquakes. This study provides quantitative and qualitative data about the geotechnical attributes and engineering geological nature of the sea-cut cliff located at Redcliffs. Results from surveying the geology of Redcliffs show that the exposed lithology of the cliff face is a variably jointed rock body of welded and (relatively intact) unwelded ignimbrite, a predominantly massive unit of brecciated tuff, and a covering of wind-blown loess and soil deposit (commonly found throughout Canterbury) on top of the cliff. Moreover, detailing the external component of the slope profile shows that Redcliffs’ cliff is a 40 – 80 m cliff with two intersecting (NE and SE facing) slope aspects. The (remotely) measured geometry of the cliff face comprises of multiple outstanding gradients, averaging a slope angle of ~67 degrees (post-13 June 2011), where the steepest components are ~80 degrees, whereas the gentle sloping sections are ~44 degrees. The physical structure of Redcliffs’ cliff drastically changed after each collapse, whereby seismically induced alterations to the slope geometry resulted in material deposited on the talus at the base of the cliff. Prior to the first collapse, the variance of the gradient down the slope was minimal, with the SE Face being the most variable with up to three major gradients on one cross section. However, after each major collapse, the variability increased with more parts of the cliff face having more than one major gradient that is steeper or gentler than the remainder of the slope. The estimated volume of material lost as a result of the gradient changes was 28,267 m³ in February and 11,360 m³ in June 2011. In addition, surveys of the cliff top after the failure incidents revealed the development of fissures along the cliff edge. Monitoring 10 fissures over three months indicated that fissured by the cliff edge respond to intense seismicity (generally ≥ Mw 4) by widening. Redcliffs’ cliff collapsed on two separate occasions as a result of an accumulated amount of damage of the rock masses in the cliff (caused by weathering and erosion over time), and two Mw 6.2 trigger earthquakes which shook the Redcliffs and the surrounding area at a Peak Ground Acceleration (PGA) estimated to be around 2 g. The results of the theoretical study suggests that PGA levels felt on-site during both instances of failure are the result of three major factors: source of the quake and the site affected; topographic amplification of the ground movement; the short distance between the source and the cliff for both fault ruptures; the focus of seismic energy in the direction of thrust faulting along a path that intercepts Redcliffs (and the Port Hills). Ultimately, failure on the NE and SE Faces of Redcliffs’ cliff was concluded to be global as every part of the exposed cliff face deposited a significant volume of material on the talus at the base of the cliff, with the exception of one section on the NE Face. The cliff collapses was a concurrent process that is a single (non-monotonic) event that operated as a complex series of (primarily) toppling rock falls, some sliding of blocks, and slumping of the soil mantle on top of the cliff. The first collapse had a mixture of equivalent continua slope movement of the heavily weathered / damaged surface of the cliff face, and discontinuous slope movement of the jointed inner slope (behind the heavily weathered surface); whereas the second collapse resulted in only discontinuous slope movement on account of the freshly exposed cliff face that had damage to the rock masses, in the form of old and (relatively) new discontinuous fractures, induced by earthquakes and aftershocks leading up to the point of failure.
Coastal and river environments are exposed to a number of natural hazards that have the potential to negatively affect both human and natural environments. The purpose of this research is to explain that significant vulnerabilities to seismic hazards exist within coastal and river environments and that coasts and rivers, past and present, have played as significant a role as seismic, engineering or socio-economic factors in determining the impacts and recovery patterns of a city following a seismic hazard event. An interdisciplinary approach was used to investigate the vulnerability of coastal and river areas in the city of Christchurch, New Zealand, following the Canterbury Earthquake Sequence, which began on the 4th of September 2010. This information was used to identify the characteristics of coasts and rivers that make them more susceptible to earthquake induced hazards including liquefaction, lateral spreading, flooding, landslides and rock falls. The findings of this research are applicable to similar coastal and river environments elsewhere in the world where seismic hazards are also of significant concern. An interdisciplinary approach was used to document and analyse the coastal and river related effects of the Canterbury earthquake sequence on Christchurch city in order to derive transferable lessons that can be used to design less vulnerable urban communities and help to predict seismic vulnerabilities in other New Zealand and international urban coastal and river environments for the future. Methods used to document past and present features and earthquake impacts on coasts and rivers in Christchurch included using maps derived from Geographical Information Systems (GIS), photographs, analysis of interviews from coastal, river and engineering experts, and analysis of secondary data on seismicity, liquefaction potential, geology, and planning statutes. The Canterbury earthquake sequence had a significant effect on Christchurch, particularly around rivers and the coast. This was due to the susceptibility of rivers to lateral spreading and the susceptibility of the eastern Christchurch and estuarine environments to liquefaction. The collapse of river banks and the extensive cracking, tilting and subsidence that accompanied liquefaction, lateral spreading and rock falls caused damage to homes, roads, bridges and lifelines. This consequently blocked transportation routes, interrupted electricity and water lines, and damaged structures built in their path. This study found that there are a number of physical features of coastal and river environments from the past and the present that have induced vulnerabilities to earthquake hazards. The types of sediments found beneath eastern Christchurch are unconsolidated fine sands, silts, peats and gravels. Together with the high water tables located beneath the city, these deposits made the area particularly susceptible to liquefaction and liquefaction-induced lateral spreading, when an earthquake of sufficient size shook the ground. It was both past and present coastal and river processes that deposited the types of sediments that are easily liquefied during an earthquake. Eastern Christchurch was once a coastal and marine environment 6000 years ago when the shoreline reached about 6 km inland of its present day location, which deposited fine sand and silts over this area. The region was also exposed to large braided rivers and smaller spring fed rivers, both of which have laid down further fine sediments over the following thousands of years. A significant finding of this study is the recognition that the Canterbury earthquake sequence has exacerbated existing coastal and river hazards and that assessments and monitoring of these changes will be an important component of Christchurch’s future resilience to natural hazards. In addition, patterns of recovery following the Canterbury earthquakes are highlighted to show that coasts and rivers are again vulnerable to earthquakes through their ability to recovery. This city’s capacity to incorporate resilience into the recovery efforts is also highlighted in this study. Coastal and river areas have underlying physical characteristics that make them increasingly vulnerable to the effects of earthquake hazards, which have not typically been perceived as a ‘coastal’ or ‘river’ hazard. These findings enhance scientific and management understanding of the effects that earthquakes can have on coastal and river environments, an area of research that has had modest consideration to date. This understanding is important from a coastal and river hazard management perspective as concerns for increased human development around coastlines and river margins, with a high seismic risk, continue to grow.
As part of the 'Project Masonry' Recovery Project funded by the New Zealand Natural Hazards Research Platform, commencing in March 2011, an international team of researchers was deployed to document and interpret the observed earthquake damage to masonry buildings and to churches as a result of the 22nd February 2011 Christchurch earthquake. The study focused on investigating commonly encountered failure patterns and collapse mechanisms. A brief summary of activities undertaken is presented, detailing the observations that were made on the performance of and the deficiencies that contributed to the damage to approximately 650 inspected unreinforced clay brick masonry (URM) buildings, to 90 unreinforced stone masonry buildings, to 342 reinforced concrete masonry (RCM) buildings, to 112 churches in the Canterbury region, and to just under 1100 residential dwellings having external masonry veneer cladding. In addition, details are provided of retrofit techniques that were implemented within relevant Christchurch URM buildings prior to the 22nd February earthquake and brief suggestions are provided regarding appropriate seismic retrofit and remediation techniques for stone masonry buildings. http://www.nzsee.org.nz/publications/nzsee-quarterly-bulletin/
The author followed five primary (elementary) schools over three years as they responded to and began to recover from the 2010–2011 earthquakes in and around the city of Christchurch in the Canterbury region of New Zealand. The purpose was to capture the stories for the schools themselves, their communities, and for New Zealand’s historical records. From the wider study, data from the qualitative interviews highlighted themes such as children’s responses or the changing roles of principals and teachers. The theme discussed in this article, however, is the role that schools played in the provision of facilities and services to meet (a) physical needs (food, water, shelter, and safety); and (b) emotional, social, and psychological needs (communication, emotional support, psychological counseling, and social cohesion)—both for themselves and their wider communities. The role schools played is examined across the immediate, short-, medium-, and long-term response periods before being discussed through a social bonding theoretical lens. The article concludes by recommending stronger engagement with schools when considering disaster policy, planning, and preparation http://www.schoolcommunitynetwork.org/SCJ.aspx
Disasters that significantly affect people typically result in the production of documents detailing disaster lessons. This was the case in the 2010 and 2011 Canterbury earthquakes, as government and emergency response agencies, community organisations, and the media, engaged in the practice of producing and reporting disaster lessons. This thesis examines the disaster lessons that were developed by emergent groups following the Canterbury earthquakes (4 September 2010 and 22 February 2011). It adopts a Foucauldian analysis approach to investigate both the construction of disaster lessons and to document how this practice has come to dominate postdisaster activity following the Canterbury earthquakes. The study involved an analysis of academic literature, public documents and websites and interviews with key members of a range of Canterbury based emergent community groups. This material was used to generate a genealogy of disaster lessons, which was given in order to generate an account of how disaster lessons emerged and have come to dominate as a practice of disaster management. The thesis then examines the genealogy through the concept of governmentality so as to demonstrate how this discourse of disaster lessons has come to be used as a governing rationale that shapes and guides the emergent groups conduct in postdisaster New Zealand.
1. Background and Objectives This poster presents results from ground motion simulations of small-to-moderate magnitude (3.5≤Mw≤5.0) earthquake events in the Canterbury, New Zealand region using the Graves and Pitarka (2010,2015) methodology. Subsequent investigation of systematic ground motion effects highlights the prediction bias in the simulations which are also benchmarked against empirical ground motion models (e.g. Bradley (2013)). In this study, 144 earthquake ruptures, modelled as point sources, are considered with 1924 quality-assured ground motions recorded across 45 strong motion stations throughout the Canterbury region, as shown in Figure 1. The majority of sources are Mw≥4.0 and have centroid depth (CD) 10km or shallower. Earthquake source descriptions were obtained from the GeoNet New Zealand earthquake catalogue. The ground motion simulations were performed within a computational domain of 140km x 120km x 46km with a finite difference grid spacing of 0.1km. The low-frequency (LF) simulations utilize the 3D Canterbury Velocity Model while the high-frequency (HF) simulations utilize a generic regional 1D velocity model. In the LF simulations, a minimum shear wave velocity of 500m/s is enforced, yielding a maximum frequency of 1.0Hz.
