Recent surface-rupturing earthquakes in New Zealand have highlighted significant exposure and vulnerability of the road network to fault displacement. Understanding fault displacement hazard and its impact on roads is crucial for mitigating risks and enhancing resilience. There is a need for regional-scale assessments of fault displacement to identify vulnerable areas within the road network for the purposes of planning and prioritising site-specific investigations. This thesis employs updated analysis of data from three historical surface-rupturing earthquakes (Edgecumbe 1987, Darfield 2010, and Kaikoūra 2016) to develop an empirical model that addresses the gap in regional fault displacement hazard analysis. The findings contribute to understanding of • How to use seismic hazard model inputs for regional fault displacement hazard analysis • How faulting type and sediment cover affects the magnitude and spatial distribution of fault displacement • How the distribution of displacement and regional fault displacement hazard is impacted by secondary faulting • The inherent uncertainties and limitations associated with employing an empirical approach at a regional scale • Which sections of New Zealand’s roading network are most susceptible to fault displacement hazard and warrant site-specific investigations • Which regions should prioritise updating emergency management plans to account for post-event disruptions to roading. I used displacement data from the aforementioned historical ruptures to generate displacement versus distance-to-fault curves for various displacement components, fault types, and geological characteristics. Using those relationships and established relationships for along-strike displacement, displacement contours were generated surrounding active faults within the NZ Community Fault Model. Next, I calculated a new measure of 1D strain along roads as well as relative hazard, which integrated 1D strain and normalised slip rate data. Summing these values at the regional level identified areas of heightened relative hazard across New Zealand, and permits an assessment of the susceptibility of road networks using geomorphon land classes as proxies for vulnerability. The results reveal that fault-parallel displacements tend to localise near the fault plane, while vertical and fault-perpendicular displacements sustain over extended distances. Notably, no significant disparities were observed in off-fault displacement between the hanging wall and footwall sides of the fault, or among different surface geology types, potentially attributed to dataset biases. The presence of secondary faulting in the dataset contributes to increased levels of tectonic displacement farther from the fault, highlighting its significance in hazard assessments. Furthermore, fault displacement contours delineate broader zones around dip-slip faults compared to strike-slip faults, with correlations identified between fault length and displacement width. Road ‘strain’ values are higher around dip-slip faults, with notable examples observed in the Westland and Buller Districts. As expected, relative hazard analysis revealed elevated values along faults with high slip rates, notably along the Alpine Fault. A regional-scale analysis of hazard and exposure reveals heightened relative hazard in specific regions, including Wellington, Southern Hawke’s Bay, Central Bay of Plenty, Central West Coast, inland Canterbury, and the Wairau Valley of Marlborough. Notably, the Central West Coast exhibits the highest summed relative hazard value, attributed to the fast-slipping Alpine Fault. The South Island generally experiences greater relative hazard due to larger and faster-slipping faults compared to the North Island, despite having fewer roads. Central regions of New Zealand face heightened risk compared to Southern or Northern regions. Critical road links intersecting high-slipping faults, such as State Highways 6, 73, 1, and 2, necessitate prioritisation for site-specific assessments, emergency management planning and targeted mitigation strategies. Roads intersecting with the Alpine Fault are prone to large parallel displacements, requiring post-quake repair efforts. Mitigation strategies include future road avoidance of nearby faults, modification of road fill and surface material, and acknowledgement of inherent risk, leading to prioritised repair efforts of critical roads post-quake. Implementing these strategies enhances emergency response efforts by improving accessibility to isolated regions following a major surface-rupturing event, facilitating faster supply delivery and evacuation assistance. This thesis contributes to the advancement of understanding fault displacement hazard by introducing a novel regional, empirical approach. The methods and findings highlight the importance of further developing such analyses and extending them to other critical infrastructure types exposed to fault displacement hazard in New Zealand. Enhancing our comprehension of the risks associated with fault displacement hazard offers valuable insights into various mitigation strategies for roading infrastructure and informs emergency response planning, thereby enhancing both national and global infrastructure resilience against geological hazards.
Study region: Christchurch, New Zealand. Study focus: Low-lying coastal cities worldwide are vulnerable to shallow groundwater salinization caused by saltwater intrusion and anthropogenic activities. Shallow groundwater salinization can have cascading negative impacts on municipal assets, but this is rarely considered compared to impacts of salinization on water supply. Here, shallow groundwater salinity was sampled at high spatial resolution (1.3 piezometer/km²), then mapped and spatially interpolated. This was possible due to a uniquely extensive set of shallow piezometers installed in response to the 2010–11 Canterbury Earthquake Sequence to assess liquefaction risk. The municipal assets located within the brackish groundwater areas were highlighted. New hydrological insights for the region: Brackish groundwater areas were centred on a spit of coastal sand dunes and inside the meander of a tidal river with poorly drained soils. The municipal assets located within these areas include: (i) wastewater and stormwater pipes constructed from steel-reinforced concrete, which, if damaged, are vulnerable to premature failure when exposed to chloride underwater, and (ii) 41 parks and reserves totalling 236 ha, within which salt-intolerant groundwater-dependent species are at risk. This research highlights the importance of determining areas of saline shallow groundwater in low-lying coastal urban settings and the co-located municipal assets to allow the prioritisation of sites for future monitoring and management.
Study region: Christchurch, New Zealand. Study focus: Low-lying coastal cities worldwide are vulnerable to shallow groundwater salinization caused by saltwater intrusion and anthropogenic activities. Shallow groundwater salinization can have cascading negative impacts on municipal assets, but this is rarely considered compared to impacts of salinization on water supply. Here, shallow groundwater salinity was sampled at high spatial resolution (1.3 piezometer/km2 ), then mapped and spatially interpolated. This was possible due to a uniquely extensive set of shallow piezometers installed in response to the 2010–11 Canterbury Earthquake Sequence to assess liquefaction risk. The municipal assets located within the brackish groundwater areas were highlighted. New hydrological insights for the region: Brackish groundwater areas were centred on a spit of coastal sand dunes and inside the meander of a tidal river with poorly drained soils. The municipal assets located within these areas include: (i) wastewater and stormwater pipes constructed from steel-reinforced concrete, which, if damaged, are vulnerable to premature failure when exposed to chloride underwater, and (ii) 41 parks and reserves totalling 236 ha, within which salt-intolerant groundwater-dependent species are at risk. This research highlights the importance of determining areas of saline shallow groundwater in low-lying coastal urban settings and the co-located municipal assets to allow the prioritisation of sites for future monitoring and management.
Natural hazard disasters often have large area-wide impacts, which can cause adverse stress-related mental health outcomes in exposed populations. As a result, increased treatment-seeking may be observed, which puts a strain on the limited public health care resources particularly in the aftermath of a disaster. It is therefore important for public health care planners to know whom to target, but also where and when to initiate intervention programs that promote emotional wellbeing and prevent the development of mental disorders after catastrophic events. A large body of literature assesses factors that predict and mitigate disaster-related mental disorders at various time periods, but the spatial component has rarely been investigated in disaster mental health research. This thesis uses spatial and spatio-temporal analysis techniques to examine when and where higher and lower than expected mood and anxiety symptom treatments occurred in the severely affected Christchurch urban area (New Zealand) after the 2010/11 Canterbury earthquakes. High-risk groups are identified and a possible relationship between exposure to the earthquakes and their physical impacts and mood and anxiety symptom treatments is assessed. The main research aim is to test the hypothesis that more severely affected Christchurch residents were more likely to show mood and anxiety symptoms when seeking treatment than less affected ones, in essence, testing for a dose-response relationship. The data consisted of mood and anxiety symptom treatment information from the New Zealand Ministry of Health’s administrative databases and demographic information from the National Health Index (NHI) register, when combined built a unique and rich source for identifying publically funded stress-related treatments for mood and anxiety symptoms in almost the whole population of the study area. The Christchurch urban area within the Christchurch City Council (CCC) boundary was the area of interest in which spatial variations in these treatments were assessed. Spatial and spatio-temporal analyses were done by applying retrospective space-time and spatial variation in temporal trends analysis using SaTScan™ software, and Bayesian hierarchical modelling techniques for disease mapping using WinBUGS software. The thesis identified an overall earthquake-exposure effect on mood and anxiety symptom treatments among Christchurch residents in the context of the earthquakes as they experienced stronger increases in the risk of being treated especially shortly after the catastrophic 2011 Christchurch earthquake compared to the rest of New Zealand. High-risk groups included females, elderly, children and those with a pre-existing mental illness with elderly and children especially at-risk in the context of the earthquakes. Looking at the spatio-temporal distribution of mood and anxiety symptom treatments in the Christchurch urban area, a high rates cluster ranging from the severely affected central city to the southeast was found post-disaster. Analysing residential exposure to various earthquake impacts found that living in closer proximity to more affected areas was identified as a risk factor for mood and anxiety symptom treatments, which largely confirms a dose-response relationship between level of affectedness and mood and anxiety symptom treatments. However, little changes in the spatial distribution of mood and anxiety symptom treatments occurred in the Christchurch urban area over time indicating that these results may have been biased by pre-existing spatial disparities. Additionally, the post-disaster mobility activity from severely affected eastern to the generally less affected western and northern parts of the city seemed to have played an important role as the strongest increases in treatment rates occurred in less affected northern areas of the city, whereas the severely affected eastern areas tended to show the lowest increases. An investigation into the different effects of mobility confirmed that within-city movers and temporary relocatees were generally more likely to receive care or treatment for mood or anxiety symptoms, but moving within the city was identified as a protective factor over time. In contrast, moving out of the city from minor, moderately or severely damaged plain areas of the city, which are generally less affluent than Port Hills areas, was identified as a risk factor in the second year post-disaster. Moreover, residents from less damaged plain areas of the city showed a decrease in the likelihood of receiving care or treatment for mood or anxiety symptoms compared to those from undamaged plain areas over time, which also contradicts a possible dose-response relationship. Finally, the effects of the social and physical environment, as well as community resilience on mood and anxiety symptom treatments among long-term stayers from Christchurch communities indicate an exacerbation of pre-existing mood and anxiety symptom treatment disparities in the city, whereas exposure to ‘felt’ earthquake intensities did not show a statistically significant effect. The findings of this thesis highlight the complex relationship between different levels of exposure to a severe natural disaster and adverse mental health outcomes in a severely affected region. It is one of the few studies that have access to area-wide health and impact information, are able to do a pre-disaster / post-disaster comparison and track their sample population to apply spatial and spatio-temporal analysis techniques for exposure assessment. Thus, this thesis enhances knowledge about the spatio-temporal distribution of adverse mental health outcomes in the context of a severe natural disaster and informs public health care planners, not only about high-risk groups, but also where and when to target health interventions. The results indicate that such programs should broadly target residents living in more affected areas as they are likely to face daily hardship by living in a disrupted environment and may have already been the most vulnerable ones before the disaster. Special attention should be focussed on women, elderly, children and people with pre-existing mental illnesses as they are most likely to receive care or treatment for stress-related mental health symptoms. Moreover, permanent relocatees from affected areas and temporarily relocatees shortly after the disaster may need special attention as they face additional stressors due to the relocation that may lead to the development of adverse mental health outcomes needing treatment.
While it is well known that challenging and distressing events can negatively impact people’s psychological and physical state, increasingly researchers have investigated how challenging or stressful life circumstances can lead to the phenomenon of posttraumatic growth: positive psychological or life changes that can emerge from potentially traumatic events. Posttraumatic growth has been investigated primarily with people displaying varying levels of posttraumatic stress symptoms and other psychopathology due to theories suggesting that resilience would prohibit posttraumatic growth. Few studies have examined growth amongst resilient people. The current study examined posttraumatic growth in a sample of sixty psychologically healthy people who experienced the Canterbury earthquake sequence of 2010-2011. The current study is a follow-up study that used thematic analysis to explore: (1) Whether posttraumatic growth is evident nine years after the Canterbury earthquake sequence and approximately six years after baseline assessment; and (2) What themes may facilitate the posttraumatic growth process in psychologically healthy people. Data were collected using semi-structured interviews. Thematic analysis revealed four themes describing participants’ experiences of growth: New possibilities, reappraisal of life and priorities, positive changes in self-perception and closer more meaningful relationships. Themes describing posttraumatic growth provide evidence for research question one. Thematic analysis revealed three main themes and multiple subthemes that may facilitate the process of growth in psychologically healthy people: Hardship, optimistic positive appraisal and people helping people. Themes describing processes that may lead to growth provide evidence for research question two. Results of the current study provide insights about the experience of growth in psychologically healthy people and cognitive and psychosocial factors that may facilitate growth in resilient individuals.
Elevated levels of trace elements in the environment are of great concern because of their persistence, and their high potential to harm living organisms. The exposure of aquatic biota to trace elements can lead to bioaccumulation, and toxicity can result. Furthermore, the transfer of these elements through food chains can result in exposure to human consumers. Sea-fill or coastal fill sites are among the major anthropogenic sources of trace elements to the surrounding marine environment. For example, in the Maldives, Thilafushi Island is a sea-fill site consisting of assorted municipal solid waste, with multiple potential sources of trace elements. However, there is limited data on environmental trace element levels in the Maldives, and although seafood is harvested from close to this site, there is no existing data regarding trace element levels in Maldivian diets. Following the Christchurch earthquakes of 2011,
Background Liquefaction induced land damage has been identified in more than 13 notable New Zealand earthquakes within the past 150 years, as presented on the timeline below. Following the 2010-2011 Canterbury Earthquake Sequence (CES), the consequences of liquefaction were witnessed first-hand in the city of Christchurch and as a result the demand for understanding this phenomenon was heightened. Government, local councils, insurers and many other stakeholders are now looking to research and understand their exposure to this natural hazard.
Following exposure to trauma, stress reactions are initially adaptive. However, some individuals’ psychological response can become maladaptive with long-lasting impairment to functioning. Most people with initial symptoms of stress recover, and thus it is important to distinguish individuals who are at risk of continuing difficulties so that resources are allocated appropriately. Investigations of predictors of PTSD development have largely focused on relational and combat-related trauma, with very limited research looking at natural disasters. This study assessed the nature and severity of psychological difficulties experienced in 101 people seeking treatment following exposure to a significant earthquake that killed 185 people. Peritraumatic dissociation, posttraumatic stress symptoms, symptoms of anxiety, symptoms of depression, and social isolation were assessed. Descriptive analyses revealed the sample to be a highly impaired group, with particularly high levels of posttraumatic stress symptoms. Path analysis was used to determine whether the experience of some psychological difficulties predicted experience of others. As hypothesised, peritraumatic dissociation was found to predict posttraumatic stress symptoms and symptoms of anxiety. Posttraumatic stress symptoms then predicted symptoms of anxiety and symptoms of depression. Depression and anxiety were highly correlated. Contrary to expectations, social isolation was not significantly related to any other psychological variables. These findings justify the provision of psychological support following a natural disaster and suggest the benefit of assessing peritraumatic dissociation and posttraumatic stress symptoms soon after the event to identify people in need of monitoring and intervention.
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.
This dissertation contains three essays on the impact of unexpected adverse events on student outcomes. All three attempt to identify causal inference using plausibly exogenous shocks and econometric tools, applied to rich administrative data. In Chapter 2, I present evidence of the causal effects of the 2011 Christchurch earthquake on tertiary enrolment and completion. Using the shock of the 2011 earthquake on high school students in the Canterbury region, I estimate the effect of the earthquake on a range of outcomes including tertiary enrolment, degree completion and wages. I find the earthquake causes a substantial increase in tertiary enrolment, particularly for low ability high school leavers from damaged schools. However, I find no evidence that low ability students induced by the earthquake complete a degree on time. In Chapter 3, I identify the impact of repeat disaster exposure on university performance, by comparing outcomes for students who experience their first earthquake while in university, to outcomes for students with prior earthquake exposure. Using a triple-differences estimation strategy with individual-by-year fixed effects, I identify a precise null effect, suggesting that previous experience of earthquakes is not predictive of response to an additional shock two years later. The final chapter investigates the impact of injuries sustained in university on academic performance and wages, using administrative data including no-fault insurance claims, emergency department attendance and hospital admissions, linked with tertiary enrolment. I find injuries, including minor injuries, have a negative effect on re-enrolment, degree completion and grades in university.
Recent tsunami events have highlighted the importance of effective tsunami risk management strategies (including land-use planning, structural and natural mitigation, warning systems, education and evacuation planning). However, the rarity of tsunami means that empirical data concerning reactions to tsunami warnings and evacuation behaviour is rare when compared to findings for evacuations from other hazards. More knowledge is required to document the full evacuation process, including responses to warnings, pre-evacuation actions, evacuation dynamics, and the return home. Tsunami evacuation modelling has the potential to inform evidence-based tsunami risk planning and response. However, to date, tsunami evacuation models have largely focused on the timings of evacuations, rather than behaviours of those evacuating. In this research, survey data was gathered from coastal communities in Banks Peninsula and Christchurch, New Zealand, relating to behaviours and actions during the November 14th 2016 Kaikōura earthquake tsunami. Survey questions asked about immediate actions following the earthquake shaking, reactions to tsunami warnings, pre-evacuation actions, evacuation dynamics and details on congestion. This data was analysed to characterise trends and identify factors that influenced evacuation actions and behaviour, and was further used to develop a realistic evacuation model prototype to evaluate the capacity of the roading network in Banks Peninsula during a tsunami evacuation. The evacuation model incorporated tsunami risk management strategies that have been implemented by local authorities, and exposure and vulnerability data, alongside the empirical data collected from the survey. This research enhances knowledge of tsunami evacuation behaviour and reactions to tsunami warnings, and can be used to refine evacuation planning to ensure that people can evacuate efficiently, thereby reducing their tsunami exposure and personal risk.
The current study examined the psychological effects of recurring earthquake aftershocks in the city of Christchurch, New Zealand, which began in September 2010. Although it has been identified that exposure to ongoing adverse events such as continuing terrorist attacks generally leads to the development of increasing symptomology over time, differences in perceived controllability and blame between man-made and natural adverse events may contribute to differences in symptom trajectories. Residents of two Christchurch suburbs differentially affected by the earthquakes (N = 128) were assessed on measures of acute stress disorder, generalised anxiety, and depression, at two time points approximately 4-5 months apart, in order to determine whether symptoms intensified or declined over time in the face of ongoing aftershocks. At time 1, clinically significant levels of acute stress were identified in both suburbs, whereas clinical elevations in depression and anxiety were only evident in the most affected suburb. By time 2, both suburbs had fallen below the clinical range on all three symptom types, identifying a pattern of habituation to the aftershocks. Acute stress symptoms at time 2 were the most highly associated with the aftershocks, compared to symptoms of generalised anxiety and depression which were identified by participant reports to be more likely associated with other earthquake-related factors, such as insurance troubles and less frequent socialisation. The finding that exposure to ongoing earthquake aftershocks leads to a decline in symptoms over time may have important implications for the assessment of traumatic stress-related disorders, and provision of services following natural, as compared to man-made, adverse events.
Understanding posttraumatic stress disorder (PTSD) symptoms in police first-responders is an underdeveloped field. Using a cross-sectional survey, this study investigated demographic and occupational characteristics, coping resources and processes, along with first-responder roles and consequences 18 months following a disaster. Hierarchical linear regression (N = 576) showed that greater symptom levels were significantly positively associated with negative emotional coping (β = .31), a communications role (β = .08) and distress following exposure to resource losses (β = .14), grotesque scenes (β = .21), personal harm (β = .14), and concern for significant others (β = .17). Optimism alone was negatively associated (β=−15), with the overall model being a modest fit (adjusted R2 = .39). The findings highlight variables for further study in police.
The greater Wellington region, New Zealand, is highly vulnerable to large earthquakes. While attention has been paid to the consequences of earthquake damage to road, electricity and water supply networks, the consequences of wastewater network damage for public health, environmental health and habitability of homes remain largely unknown for Wellington City. The Canterbury and Kaikōura earthquakes have highlighted the vulnerability of sewerage systems to disruption during a disaster. Management of human waste is one of the critical components of disaster planning to reduce faecal-oral transmission of disease and exposure to disease-bearing vectors. In Canterbury and Kaikōura, emergency sanitation involved a combination of Port-a-loos, chemical toilets and backyard long-drops. While many lessons may be learned from experiences in Canterbury earthquakes, it is important to note that isolation is likely to be a much greater factor for Wellington households, compared to Christchurch, due to the potential for widespread landslides in hill suburbs affecting road access. This in turn implies that human waste may have to be managed onsite, as options such as chemical toilets and Port-a-loos rely completely on road access for delivering chemicals and collecting waste. While some progress has been made on options such as emergency composting toilets, significant knowledge gaps remain on how to safely manage waste onsite. In order to bridge these gaps, laboratory tests will be conducted through the second half of 2019 to assess the pathogen die-off rates in the composting toilet system with variables being the type of carbon bulking material and the addition of a Bokashi composting activator.
Small, tight-knit communities, are complex to manage from outside during a disaster. The township of Lyttelton, New Zealand, and the communities of Corsair Bay, Cass Bay, and Rapaki to the east, are especially more so difficult due to the terrain that encloses them, which caused them to be cut-off from Christchurch, the largest city in the South Island, barely 10 km away, after the Mw 7.1 Darfield Earthquake and subsequent Canterbury Earthquake Sequence. Lyttelton has a very strong and deep-rooted community spirit that draws people to want to be a part of Lyttelton life. It is predominantly residential on the slopes, with retail space, service and light industry nestled near the harbour. It has heritage buildings stretching back to the very foundation of Canterbury yet hosts the largest, modern deep-water port for the region. This study contains two surveys: one circulated shortly before the Darfield Earthquake and one circulated in July 2011, after the Christchurch and Sumner Earthquakes. An analytical comparison of the participants’ household preparedness for disaster before the Darfield Earthquake and after the Christchurch and Sumner Earthquakes was performed. A population spatiotemporal distribution map was produced that shows the population in three-hourly increments over a week to inform exposure to vulnerability to natural hazards. The study went on to analyse the responses of the participants in the immediate period following the Chrsitchurch and Sumner Earthquakes, including their homeward and subsequent journeys, and the decision to evacuate or stay in their homes. Possible predictors to a decision to evacuate some or all members of the household were tested. The study also asked participants’ views on the events since September 2010 for analysis.
The Canterbury region of New Zealand experienced a sequence of strong earthquakes during 2010-2011. Responses included government acquisition of many thousands of residential properties in the city of Christchurch in areas with severe earthquake effects. A large and contiguous tract of this ‘red zoned’ land lies in close proximity to the Ōtākaro / Avon River and is known as the Avon-Ōtākaro Red Zone (AORZ). The focus of this study was to provide an overview of the floodplain characteristics of the AORZ and review of international experience in ecological restoration of similar river margin and floodplain ecosystems to extract restoration principles and associated learnings. Compared to pre-earthquake ground levels, the dominant trend in the AORZ is subsidence, together with lateral movement especially in the vicinity of waterway. An important consequence of land subsidence in the lower Ōtākaro / Avon River is greater exposure to flooding and the effects of sea level rise. Scenario modelling for sea level rise indicates that much of the AORZ is exposed to inundation within a 100 year planning horizon based on a 1 m sea level rise. As with decisions on built infrastructure, investments in nature-based ‘green infrastructure’ also require a sound business case including attention to risks posed by climate change. Future-proofing of the expected benefits of ecological restoration must therefore be secured by design. Understanding and managing the hydrology and floodplain dynamics are vital to the future of the AORZ. However, these characteristics are shared by other floodplain and river restoration projects worldwide. Identifying successful approaches provides a useful a source of useful information for floodplain planning in the AORZ. This report presents results from a comparative case study of three international examples to identify relevant principles for large-scale floodplain management at coastal lowland sites.
Fatal earthquakes such as that which occurred in Christchurch on February 22nd 2011, can result in survivors having difficulties with cognitively processing the event, which may be the precursor to posttraumatic stress symptoms. Trauma related dissociation has been proposed to be a mechanism related to these cognitive processing difficulties. Most research focusing on information processing and dissociation post-trauma has conducted controlled analogue studies or has not focused solely on information processing and dissociation. There is also scant research on these constructs across therapy. In response to this gap in research, two studies were developed. An association was proposed between dissociation and information processing as demonstrated by an increase in conceptual processing and a reduction in dissociation. It was predicted that an improvement in these constructs would be related to a reduction in PTSD symptoms over therapy. Study1 applied a case-study design to 5 individuals who were attending therapy for post-traumatic stress disorder in response to the trauma they had experienced from the Christchurch earthquakes. Study 2 assessed information processing and dissociation (via self and observer report) in 20 individuals who had direct exposure to the effects of the earthquake. Earthquake information processing and dissociation were assessed as they were happening nearly two year’s post-quake using correlation analyses and hierarchical regressions. The hypotheses were partially confirmed, in that an increase in conceptual processing was not shown to be associated with a reduction in dissociation. However, an increase in conceptual processing was shown to be related to trauma symptom improvement particularly for re-experiencing symptoms. In addition, study 2 demonstrated a possible relationship between trait dissociation and arousal symptoms. These findings partially support the proposed role information processing and dissociation play in the recovery from PTSD. The findings suggest that trauma related difficulties should be assessed as early as possible to resolve issues related to a delay in symptom reporting.
Following a natural disaster, children are prone to various reactions and maladaptive responses as a result of exposure to a highly stressful and potentially traumatic event. Children’s responses can range from an acute stress response to post-traumatic-stress disorder or may fall somewhere in between. While responses to highly stressful events vary, a common finding is that children will develop sleep problems. This was found following the Christchurch September 2010 and February 2011 earthquakes. The purpose of this study was to investigate the context and phenomenology of the sleep problems of a small number of children experiencing these and the 2016 Kaikoura earthquakes, including possible mechanisms of effect. Participants were four families, including four mothers, one father and four children. The design of this study was unique. Interview data was subjected to a content analysis, extracted themes were organised according to an ecological-transactional framework and then the factors were subject to an analysis, based on the principles of clinical reasoning, in order to identify possible mechanisms of effect. Parents reported 16 different sleep problems across children, as well as other behaviours possibly indicative of post-traumatic stress response. In total, 34 themes and 26 interactions were extracted in relation to factors identified across participants about the children’s sleep and the families’ earthquake experiences. This demonstrated how complex it is to explore the development of sleep problems in the context of disaster. Key factors identified by parents that likely played a key role in the development and perpetuation of sleep problems included earthquake related anxiety, parental mental health and conflict, the child’s emotional and behavioural problems and other negative life events following the earthquakes. The clinical implications of the analysis included being aware that such families, may not have had access to specialized support around their children’s sleep. This was much needed due to the strain such problems place on the family, especially in a post-disaster community such as Christchurch.
Climate change and population growth will increase vulnerability to natural and human-made disasters or pandemics. Longitudinal research studies may be adversely impacted by a lack of access to study resources, inability to travel around the urban environment, reluctance of sample members to attend appointments, sample members moving residence and potentially also the destruction of research facilities. One of the key advantages of longitudinal research is the ability to assess associations between exposures and outcomes by limiting the influence of sample selection bias. However, ensuring the validity and reliability of findings in longitudinal research requires the recruitment and retention of respondents who are willing and able to be repeatedly assessed over an extended period of time. This study examined recruitment and retention strategies of 11 longitudinal cohort studies operating during the Christchurch, New Zealand earthquake sequence which began in September 2010, including staff perceptions of the major impediments to study operations during/after the earthquakes and respondents’ barriers to participation. Successful strategies to assist recruitment and retention after a natural disaster are discussed. With the current COVID-19 pandemic, longitudinal studies are potentially encountering some of the issues highlighted in this paper including: closure of facilities, restricted movement of research staff and sample members, and reluctance of sample members to attend appointments. It is possible that suggestions in this paper may be implemented so that longitudinal studies can protect the operation of their research programmes.<br /><br />Key messages<br /><ul><li>Recruitment and retention of longitudinal study participants is challenging following a natural disaster.</li><br /><li>The long-lasting, global effects of the Covid 19 pandemic will increase this problem.</li><br /><li>Longitudinal study researchers should develop protocols to support retention before a disaster occurs.</li><br /><li>Researchers need to be pragmatic and flexible in the design and implementation of their studies.</li></ul>
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.
Background: There has been a psychopathology focus in disaster research examining adolescent mental health and wellbeing, but recently studies have begun to also examine wellbeing-related constructs. Although an increased risk of posttraumatic stress disorder has been established in disaster-exposed adolescents, comparatively little is known about how disasters impact adolescent wellbeing, nor how factors within the post-disaster environment interact to influence holistic adolescent mental health and wellbeing. Objective: The objective of this study was to describe the holistic mental health and wellbeing of adolescents living in an earthquake-struck city by considering a range of mental health and wellbeing indicators, as well as risk and protective factors hypothesised to influence mental health and wellbeing. The dual-factor model of mental health was used as a framework to guide this study. Method: A survey of Christchurch secondary school students was used to gather data about their subjective wellbeing, risk of low wellbeing, psychological distress, quality of life, exposure to Adverse Childhood Experiences, social support from friends and family, school connectedness, and expectations about future quality of life. Results: A slim majority of students reported good subjective wellbeing (52.3%) and high current quality of life (56.4%), whereas a larger majority reported low risk of psychological distress (79%). An equal proportion of students reported high and low risk of low wellbeing. There were no statistically significant differences in any of the variables measured between adolescents who did and did not live through the Christchurch earthquakes. Regression analyses identified that school connectedness, social support from friends and family, and future expectations of quality of life significantly predicted subjective wellbeing, risk of low wellbeing, risk of psychological distress, and current quality of life. The number of Adverse Childhood Experiences significantly predicted only risk of psychological distress when the effects of other variables were controlled for. Conclusion: The findings of this study indicate that there is a low mean level of wellbeing and quality of life in this sample of adolescents living in a severely earthquake- affected community. School connectedness, social support from family and friends, and expectations about future quality of life were shown to significantly predict variance in subjective wellbeing, quality of life, and psychological distress. This suggests that there are social and environmental factors that can be targeted to improve holistic mental health and wellbeing in disaster-affected adolescents who have experienced high levels of trauma. Conclusions in this study are limited by the representativeness of the sample, the cross- sectional nature of the study, and potential sampling bias.
Background: There has been a psychopathology focus in disaster research examining adolescent mental health and wellbeing, but recently studies have begun to also examine wellbeing-related constructs. Although an increased risk of posttraumatic stress disorder has been established in disaster-exposed adolescents, comparatively little is known about how disasters impact adolescent wellbeing, nor how factors within the post-disaster environment interact to influence holistic adolescent mental health and wellbeing. Objective: The objective of this study was to describe the holistic mental health and wellbeing of adolescents living in an earthquake-struck city by considering a range of mental health and wellbeing indicators, as well as risk and protective factors hypothesised to influence mental health and wellbeing. The dual-factor model of mental health was used as a framework to guide this study. Method: A survey of Christchurch secondary school students was used to gather data about their subjective wellbeing, risk of low wellbeing, psychological distress, quality of life, exposure to Adverse Childhood Experiences, social support from friends and family, school connectedness, and expectations about future quality of life. Results: A slim majority of students reported good subjective wellbeing (52.3%) and high current quality of life (56.4%), whereas a larger majority reported low risk of psychological distress (79%). An equal proportion of students reported high and low risk of low wellbeing. There were no statistically significant differences in any of the variables measured between adolescents who did and did not live through the Christchurch earthquakes. Regression analyses identified that school connectedness, social support from friends and family, and future expectations of quality of life significantly predicted subjective wellbeing, risk of low wellbeing, risk of psychological distress, and current quality of life. The number of Adverse Childhood Experiences significantly predicted only risk of psychological distress when the effects of other variables were controlled for. Conclusion: The findings of this study indicate that there is a low mean level of wellbeing and quality of life in this sample of adolescents living in a severely earthquake-affected community. School connectedness, social support from family and friends, and expectations about future quality of life were shown to significantly predict variance in subjective wellbeing, quality of life, and psychological distress. This suggests that there are social and environmental factors that can be targeted to improve holistic mental health and wellbeing in disaster-affected adolescents who have experienced high levels of trauma. Conclusions in this study are limited by the representativeness of the sample, the cross-sectional nature of the study, and potential sampling bias.
Background: There has been a psychopathology focus in disaster research examining adolescent mental health and wellbeing, but recently studies have begun to also examine wellbeing-related constructs. Although an increased risk of posttraumatic stress disorder has been established in disaster-exposed adolescents, comparatively little is known about how disasters impact adolescent wellbeing, nor how factors within the post-disaster environment interact to influence holistic adolescent mental health and wellbeing. Objective: The objective of this study was to describe the holistic mental health and wellbeing of adolescents living in an earthquake-struck city by considering a range of mental health and wellbeing indicators, as well as risk and protective factors hypothesised to influence mental health and wellbeing. The dual-factor model of mental health was used as a framework to guide this study. Method: A survey of Christchurch secondary school students was used to gather data about their subjective wellbeing, risk of low wellbeing, psychological distress, quality of life, exposure to Adverse Childhood Experiences, social support from friends and family, school connectedness, and expectations about future quality of life. Results: A slim majority of students reported good subjective wellbeing (52.3%) and high current quality of life (56.4%), whereas a larger majority reported low risk of psychological distress (79%). An equal proportion of students reported high and low risk of low wellbeing. There were no statistically significant differences in any of the variables measured between adolescents who did and did not live through the Christchurch earthquakes. Regression analyses identified that school connectedness, social support from friends and family, and future expectations of quality of life significantly predicted subjective wellbeing, risk of low wellbeing, risk of psychological distress, and current quality of life. The number of Adverse Childhood Experiences significantly predicted only risk of psychological distress when the effects of other variables were controlled for. Conclusion: The findings of this study indicate that there is a low mean level of wellbeing and quality of life in this sample of adolescents living in a severely earthquake- affected community. School connectedness, social support from family and friends, and expectations about future quality of life were shown to significantly predict variance in subjective wellbeing, quality of life, and psychological distress. This suggests that there are social and environmental factors that can be targeted to improve holistic mental health and wellbeing in disaster-affected adolescents who have experienced high levels of trauma. Conclusions in this study are limited by the representativeness of the sample, the cross- sectional nature of the study, and potential sampling bias.
Canterbury, New Zealand, was struck by two major earthquakes in 2010 and 2011. Using a dyadic and developmental perspective, the current thesis first aimed to determine how the experience of earthquake-related stressors (including loss of material resources, trauma exposure, and ongoing earthquake-related stressors) and stress (posttraumatic stress symptoms) impacted individuals’ intimate relationship quality (Part 1). Data were collected from a sample of 99 couples at four time points over a period of approximately 15 months, with Time 1 completed 14 months after the 2010 earthquake (eight months post the 2011 earthquake). Data were analysed using moderated growth curve modelling in an Actor-Partner Interdependence Model framework. In line with expectations, posttraumatic stress symptoms were the strongest predictors of relationship quality. More specifically, individuals’ (actor) posttraumatic stress symptoms and their partner’s posttraumatic stress symptoms had an adverse effect on their relationship quality at Time 1. Demonstrating the importance of taking a developmental perspective, the effect of partner posttraumatic stress symptoms changed over time. Although higher partner posttraumatic stress symptoms were associated with worse relationship quality in individuals (actors) at Time 1, this was no longer the case at Time 4. Differences were also found between men and women’s actor posttraumatic stress symptom slopes across time. Using the same data and analyses, Part 2 built on these findings by investigating the role of a possible posttrauma resource available within the relationship – support exchanges. Overall, results showed that individuals were protected from any adverse effects that posttraumatic stress symptoms had on relationship quality if they had more frequent support exchanges in the relationship, however, differences between men and women and slopes across time were found. Although not the case initially, individuals’ relationship quality was worse in the longer-term if their partner reported receiving lower support from them when they were experiencing high posttraumatic stress symptoms. Results also suggested that although women coped better (as evidenced through slightly better relationship quality) with higher symptoms and lower support than men initially, these efforts diminished over time. Furthermore, men appeared to be less able to cope (i.e., had worse relationship quality) with their partner’s stress when they were not receiving frequent support. Contrary to expectations, negative exchanges in the relationship did not exacerbate any adverse effects that posttraumatic stress symptoms (experienced by either individuals or their partner) had on an individuals’ relationship quality. The theoretical and practical implications and applications of these findings are discussed.
Tsunami have the potential to cause significant disruptions to society, including damage to infrastructure, critical to the every-day operation of society. Effective risk management is required to reduce the potential tsunami impacts to them. Christchurch city, situated on the eastern coast of New Zealand’s South Island, is exposed to a number of far-field tsunami hazards. Although the tsunami hazard has been well identified for Christchurch city infrastructure, the likely impacts have not been well constrained. To support effective risk management a credible and realistic infrastructure impact model is required to inform risk management planning. The objectives of this thesis are to assess the impacts on Christchurch city infrastructure from a credible, hypothetical far-field tsunami scenario. To achieve this an impact assessment process is adopted, using tsunami hazard and exposure measures to determine asset vulnerability and subsequent impacts. However, the thesis identified a number of knowledge gaps in infrastructure vulnerability to tsunami. The thesis addresses this by using two approaches: a tsunami damage matrix; and the development of tsunami fragility functions. The tsunami damage matrix pools together tsunami impacts on infrastructure literature, and post-event field observations. It represents the most comprehensive ‘look-up’ resource for tsunami impacts to infrastructure to date. This damage matrix can inform the assessment of tsunami impacts on Christchurch city infrastructure by providing a measure of damage likelihood at various hazard intensities. A more robust approach to tsunami vulnerability of infrastructure are fragility functions, which are also developed in this thesis. These were based on post-event tsunami surveys of the 2011 ‘Tohoku’ earthquake tsunami in Japan. The fragility functions are limited to road and bridge infrastructure, but represent the highest resolution measure of vulnerability for the given assets. As well as providing a measure of damage likelihood for a given tsunami hazard intensity, these also indicate a level of asset damage. The impact assessment process, and synthesized vulnerability measures, are used to run tsunami impact models for Christchurch infrastructure to determine the probability of asset damage occurring and to determine if impact will reach or exceed a given damage state. The models suggest that infrastructure damage is likely to occur in areas exposed to tsunami inundation in this scenario, with significant damage identified for low elevation roads and bridges. The results are presented and discussed in the context of the risk management framework, with emphasis on using risk assessment to inform risk treatment, monitoring and review. In summary, this thesis A) advances tsunami vulnerability and impact assessment methodologies for infrastructure and B) provides a tsunami impact assessment framework for Christchurch city infrastructure which will inform infrastructure tsunami risk management for planners, emergency managers and lifelines groups.
This study investigates evidence for linkages and fault interactions centred on the Cust Anticline in Northwest Canterbury between Starvation Hill to the southwest and the Ashley and Loburn faults to the northeast. An integrated programme of geologic, geomorphic, paleo-seismic and geophysical analyses was undertaken owing to a lack of surface exposures and difficulty in distinguishing active tectonic features from fluvial and/or aeolian features across the low-relief Canterbury Plains. LiDAR analysis identified surface expression of several previously unrecognised active fault traces across the low-relief aggradation surfaces of the Canterbury Plains. Their presence is consistent with predictions of a fault relay exploiting the structural mesh across the region. This is characterised by interactions of northeast-striking contractional faults and a series of re-activating inherited Late Cretaceous normal faults, the latter now functioning as E–W-striking dextral transpressive faults. LiDAR also allowed for detailed analysis of the surface expression of individual faults and folds across the Cust Anticline contractional restraining bend, which is evolving as a pop-up structure within the newly established dextral shear system that is exploiting the inherited, now re-activated, basement fault zone. Paleo-seismic trenches were located on the crest of the western arm of the Cust Anticline and across a previously unrecognised E–W-striking fault trace, immediately southwest of the steeply plunging Cust Anticline termination. These studies confirmed the location and structural style of north-northeast-striking faults and an E–W-striking fault associated with the development of this structural culmination. A review of available industry seismic reflection lines emphasised the presence of a series of common structural styles having the same underlying structural drivers but with varying degrees of development and expression, both in the seismic profiles and in surface elevations across the study area. Based on LiDAR surface mapping and preliminary re-analysis of industry seismic reflection data, four fault zones are identified across the restraining bend structural culminations, which together form the proposed Oxford–Cust–Ashley Fault System. The 2010–2012 Canterbury Earthquake Sequence showed many similarities to the structural pattern established across the Oxford–Cust–Ashley Fault System, emphasising the importance of identification and characterization of presently hidden fault sources, and the understanding of fault network linkages, in order to improve constraints on earthquake source potential. Improved understanding of potentially-interactive fault sources in Northwest Canterbury, with the potential for combined initial fault rupture and spatial and temporal rupture propagation across this fault system, can be used in probabilistic seismic hazard analysis for the region, which is essential for the suitability and sustainability of future social and economic development.
The Sendai Framework for Disaster Risk Reduction 2015-2030 finds that, despite progress in disaster risk reduction over the last decade “evidence indicates that exposure of persons and assets in all countries has increased faster than vulnerability has decreased, thus generating new risk and a steady rise in disaster losses” (p.4, UNISDR 2015). Fostering cooperation among relevant stakeholders and policy makers to “facilitate a science-policy interface for effective decisionmaking in disaster risk management” is required to achieve two priority areas for action, understanding disaster risk and enhancing disaster preparedness (p. 13, p. 23, UNISDR 2015). In other topic areas, the term science-policy interface is used interchangeably with the term boundary organisation. Both terms are usually used refer to systematic collaborative arrangements used to manage the intersection, or boundary, between science and policy domains, with the aim of facilitating the joint construction of knowledge to inform decision-making. Informed by complexity theory, and a constructivist focus on the functions and processes that minimize inevitable tensions between domains, this conceptual framework has become well established in fields where large complex issues have significant economic and political consequences, including environmental management, biodiversity, sustainable development, climate change and public health. To date, however, there has been little application of this framework in the disaster risk reduction field. In this doctoral project the boundary management framework informs an analysis of the research response to the 2010-2011 Canterbury Earthquake Sequence, focusing on the coordination role of New Zealand’s national Natural Hazards Research Platform. The project has two aims. It uses this framework to tell the nuanced story of the way this research coordination role evolved in response to both the complexity of the unfolding post-disaster environment, and to national policy and research developments. Lessons are drawn from this analysis for those planning and implementing arrangements across the science-policy boundary to manage research support for disaster risk reduction decision-making, particularly after disasters. The second aim is to use this case study to test the utility of the boundary management framework in the disaster risk reduction context. This requires that terminology and concepts are explained and translated in terms that make this analysis as accessible as possible across the disciplines, domains and sectors involved in disaster risk reduction. Key findings are that the focus on balance, both within organisations, and between organisations and domains, and the emphasis on systemic effects, patterns and trends, offer an effective and productive alternative to the more traditional focus on individual or organisational performance. Lessons are drawn concerning the application of this framework when planning and implementing boundary organisations in the hazard and disaster risk management context.
Worldwide turbidity is a huge concern for the health of aquatic ecosystems. Human activities on the land such as construction, deforestation, agriculture, and mining all have impacts on the amount of particulate solids that enter the world’s waterways. These particulate solids can pose a number of risks to aquatic life, but primary among them is the turbidity that they create in the water column. The way suspended solids interact with light creates cloudiness in the water which interferes with the vision, and visually mediated behaviours of aquatic organisms, particularly fish. The Avon-Heathcote estuary of Christchurch, New Zealand, is one such body of water that is subject to tremendous variation in turbidity, no doubt exacerbated by the destruction of Christchurch in the 2010 and 2011 earthquakes, as well as the subsequent ongoing rebuild. The yellow eyed mullet, Aldrichetta Forsteri, is one species that is common with the estuary, and uses it as a habitat for breeding. Though very common throughout New Zealand, and even a part of the catch of commercial fisheries, the yellow eyed mullet is a largely unstudied organism, with virtually no published scientific enquiry based on the species. The present work assesses how several behaviours of the yellow eyed mullet are effected by acute turbidity at 10, 50, 90, 130 and 170 NTU, finding that: 1) The optomotor response of mullet to 2.5 mm stripes drops to insignificant levels between 10 and 50 NTU, 2) The swimming activity of the yellow eyed mullet is highest at 10 NTU and drops to a significantly lower level at higher turbidities, 3) The grouping behaviour of small groups of yellow eyed mullet are unchanged by increasing turbidity levels, 4) that yellow eyed mullet do not exhibit significantly different behavioural response to a simulated predator at any of the tested turbidities, and 5) that yellow eyed mullet to do significantly alter their oxygen consumption during exposure to the turbidities in an increasing series. The results presented in these studies indicate that turbidites above 50 NTU pose a significant risk to the lifestyle of the yellow eyed mullet, potentially impacting their ability to perceive their surroundings, feed, school, and avoid predation. Future work has a lot of ground to cover to more precisely determine the relationship between yellow eyed mullet behaviour and physiology, and the turbidity of their environment. In particular, future work should focus more closely on the turbidities between 10 and 50 NTU, as well as looking to field work to see what the predominant predators of the mullet are, and specifically whether turbidity increases or decreases the risk of mullet being subject to avian predation. There is also considerable scope for studies on the effects of chronic turbidity upon mullet, which will add understand to the predicament of escalating turbidity and its effects upon this common and yet mysterious native fish.
Recent global tsunami events have highlighted the importance of effective tsunami risk management strategies (including land-use planning, structural and natural defences, warning systems, education and evacuation measures). However, the rarity of tsunami means that empirical data concerning reactions to tsunami warnings and tsunami evacuation behaviour is rare when compared to findings about evacuations to avoid other sources of hazard. To date empirical research into tsunami evacuations has focused on evacuation rates, rather than other aspects of the evacuation process. More knowledge is required about responses to warnings, pre-evacuation actions, evacuation dynamics and the return home after evacuations. Tsunami evacuation modelling has the potential to inform evidence-based tsunami risk planning and response. However to date tsunami evacuation models have largely focused on timings of evacuations, rather than evacuation behaviours. This Masters research uses a New Zealand case study to reduce both of these knowledge gaps. Qualitative survey data was gathered from populations across coastal communities in Banks Peninsula and Christchurch, New Zealand, required to evacuate due to the tsunami generated by the November 14th 2016 Kaikōura Earthquake. Survey questions asked about reactions to tsunami warnings, actions taken prior to evacuating and movements during the 2016 tsunami evacuation. This data was analysed to characterise trends and identify factors that influenced evacuation actions and behaviour. Finally, it was used to develop an evacuation model for Banks Peninsula. Where appropriate, the modelling inputs were informed by the survey data. Three key findings were identified from the results of the evacuation behaviour survey. Although 38% of the total survey respondents identified the earthquake shaking as a natural cue for the tsunami, most relied on receiving official warnings, including sirens, to prompt evacuations. Respondents sought further official information to inform their evacuation decisions, with 39% of respondents delaying their evacuation in order to do so. Finally, 96% of total respondents evacuated by car. This led to congestion, particularly in more densely populated Christchurch city suburbs. Prior to this research, evacuation modelling had not been completed for Banks Peninsula. The results of the modelling showed that if evacuees know how to respond to tsunami warnings and where and how to evacuate, there are no issues. However, if there are poor conditions, including if people do not evacuate immediately, if there are issues with the roading network, or if people do not know where or how to evacuate, evacuation times increase with there being more bottlenecks leading out of the evacuation zones. The results of this thesis highlight the importance of effective tsunami education and evacuation planning. Reducing exposure to tsunami risk through prompt evacuation relies on knowledge of how to interpret tsunami warnings, and when, where and how to evacuate. Recommendations from this research outline the need for public education and engagement, and the incorporation of evacuation signage, information boards and evacuation drills. Overall these findings provide more comprehensive picture of tsunami evacuation behaviour and decision making based on empirical data from a recent evacuation, which can be used to improve tsunami risk management strategies. This empirical data can also be used to inform evacuation modelling to improve the accuracy and realism of the evacuation models.
The Leader Fault was one of at least 17 faults that ruptured the ground surface across the northeastern South Island of New Zealand during the Mw 7.8 2016 Kaikōura Earthquake. The southern ~6 km of the Leader Fault, here referred to as the South Leader Fault (SLF), ruptured the North Canterbury (tectonic) Domain and is the primary focus of this study. The main objective of the thesis is to understand the key factors that contributed to the geometry and kinematics of the 2016 SLF rupture and its intersection with The Humps Fault (HF). This thesis employs a combination of techniques to achieve the primary objective, including detailed mapping of the bedrock geology, geomorphology and 2016 rupture, measurement of 2016 ground surface displacements, kinematic analysis of slip vectors from the earthquake, and logging of a single natural exposure across a 2016 rupture that was treated as a paleoseismic trench. The resulting datasets were collected in the field, from terrestrial LiDAR and InSAR imagery, and from historical (pre-earthquake) aerial photographs for a ~11 km2 study area. Surface ruptures in the study area are a miniature version of the entire rupture from the earthquake; they are geometrically and kinematically complex, with many individual and discontinuous segments of varying orientations and slip senses which are distributed across a zone up to ~3.5 km wide. Despite this variability, three main groups of ruptures have been identified. These are: 1) NE-SW striking, shallow to moderate dipping (25-45°W) faults that are approximately parallel to Cenozoic bedding with mainly reverse dip-slip and, and for the purposes of this thesis, are considered to be part of the SLF. 2) N-S striking, steeply dipping (~85°E) oblique sinistral faults that are up to the west and part of the SLF. 3) E-NE striking, moderate to steeply dipping (45-68°N) dextral reverse faults which are part of the HF. Bedding-parallel faults are interpreted to be flexural slip structures formed during folding of the near-surface Cenozoic strata, while the steeply dipping SLF ruptured a pre-existing bedrock fault which has little topographic expression. Groups 1 and 2 faults were both locally used for gravitational failure during the earthquake. Despite this non-tectonic fault movement, the slip vectors for faults that ruptured during the earthquake are broadly consistent with NCD tectonics and the regional ~100-120° trend of the principal horizontal stress/strain axes. Previous earthquake activity on the SLF is required by its displacement of Cenozoic formations but Late Quaternary slip on the fault prior to 2016 is neither supported by pre-existing fault scarps nor by changes in topography across the fault. By contrast, at least two earthquakes (including 2016) appear to have ruptured the HF from the mid Holocene, consistent with recurrence intervals of no more than ~7 kyr, and with preliminary observations from trenches on the fault farther to the west. The disparity in paleoearthquake records of the two faults suggests that they typically do not rupture together, thus it is concluded that the HF-SLF rupture pattern observed in the Kaikōura Earthquake rarely occurs in a single earthquake.
