UC Research Repository
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The UC Research Repository collects, stores and makes available original research from postgraduate students, researchers and academics based at the University of Canterbury.
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Recent Submissions
The past, present, and future of coseismic coastal deformation in Aotearoa New Zealand.
(2023) Delano, Jaime E.
Earthquakes can generate sudden coseismic uplift and subsidence that radically alter the landscape—this is nowhere more evident than at the coastline. At the coastlines, coseismic vertical deformation changes the relative sea level and impacts the landscapes, ecosystems, and infrastructure. Additionally, coastline deformation may exacerbate other hazards like tsunami, storm surges, flooding, and saline infiltration. In the relatively short historical record of Aotearoa New Zealand (c. 180 years), there have been six earthquakes in a wide variety of tectonic and geomorphic settings that have vertically deformed the coastline. Examining these events in detail, comparing how displaced coastlines adjust over time, and including with forward-looking modelling-based approaches will help build a more complete understanding of coastal coseismic deformation for multi-hazard planning.
The six historical coast-deforming earthquakes illuminate how variations in earthquake size, fault slip, and local geomorphology generate different impacts. I reviewed those six earthquakes and evaluated the extent that deformation evidence persisted over time in the geomorphic, geologic, and biologic record. The records from those provide a high level of detail for individual events and as well as potential societal impacts. However, a key takeaway from the review is that many earthquakes leave little-to-no record behind even with significant displacements, impacts to infrastructure, changes to the environment. Ultimately, a complete historical record and the processes that occur after coast-deforming earthquakes help inform paleoseismic record interpretations, hazard assessments, and forecast models.
Targeting specific historical earthquakes, like the 1987 Edgecumbe event, provides invaluable details about how rupture behaviour, site-specific conditions, fault geometry, and slip will affect coseismic surface displacement. I tested the method of using historical aerial imagery to build pre- and post-earthquake digital surface models and used the resulting datasets to measure fault displacements, compare them to the field measurements, and refine fault geometry at depth. The results show that this method is similarly effective at identifying surface deformation and measuring coseismic displacement to field methods for this event, and in some instances, better characterised and captured subtle deformation. The elastic dislocation modelling and Coulomb stress analyses suggests that the earthquake occurred on a gently dipping normal fault that may have been accelerated by a nearby inflating magma body. Results from this study better refine fault behaviour at depth and inform fault displacement hazard assessments.
Paleoseismic records are invaluable datasets because they extend the historical record and provide insight into earthquake behaviour and frequency over multiple seismic cycles. However, these records often include significant age, spatial extent, and source uncertainty. The Ahuriri Lagoon site is one the longest coastal paleoseismic records and underpins many inferences about Hikurangi Subduction Zone earthquake behaviour. I used elastic dislocation modelling to test whether crustal faults above the Hikurangi Subduction Zone could produce coseismic subsidence >0.5 m as recorded at Ahuriri Lagoon. I found that both subduction interface and offshore crustal fault earthquakes may contribute to coseismic subsidence there, which implies a potentially more ambiguous paleoseismic record both at Ahuriri Lagoon and elsewhere along the margin. Additionally, interface coupling may be more spatially or temporally heterogeneous than current geodetic-based interpretations suggest.
Forecasting hazard requires a probabilistic approach that incorporates all available data from the historical, paleoseismic, and long-term geologic records. I built the first-ever probabilistic coseismic displacement hazard model in Aotearoa New Zealand to understand the likelihood of coast-deforming earthquakes. This model focuses on the Wellington Region because it can experience coseismic displacement from the subduction interface and a dense network of upper plate faults. I combined data from the 2022 New Zealand National Seismic Hazard Model with new elastic dislocation models to produce coseismic vertical displacement forecasts over 100 years. The results show that both Hikurangi subduction earthquakes and crustal faults contribute significantly to uplift and subsidence hazards, but the site results vary based on input fault geometry, logic tree parameter choices, and distance to faults. In particular, combined probabilities of exceeding 0.2 m subsidence are c. 8-13% and may be higher with more refined crustal fault geometry. This model provides an adaptable framework for other regional, site specific, or national displacement hazard studies.
Overall, this thesis offers a unique approach to studying coseismic vertical deformation along the coastline. It examines how earthquakes can alter the coastlines at multiple spatial and temporal scales and serves as a launching point for future displacement hazard investigations.
A qualitative study of audiologists’ experiences with reflective practice in the workplace.
(2024) Sharma, Sahana
Aims: This study aimed to understand audiologists’ experiences with reflective practice (RP) in the workplace in New Zealand, and the barriers audiologists face in engaging in RP and to investigate audiologists’ experiences with RP during their student years.
Methods: Semi-structured interviews were conducted via Zoom, (n=12) Thematic analysis process was utilised to analyse the content of the interviews.
Results: Four themes were identified; 1) why audiologists reflect, 2) methods used for RP, 3) barriers to engaging in RP and 4) experiences of RP as students. A number of subthemes were identified which provided more detailed understanding of the main themes.
Conclusion: Audiologists engage in RP to learn from experiences, understanding situations that did not go as expected, analysing complex cases, managing emotions, and navigating communication within the workplace. Most commonly audiologists engage in internal reflection and verbal reflection and rarely written reflection. However, engagement in RP is restricted by a number of barriers including time constraints, lack of education about RP, clinician availability to engage in RP activities and perceived negative impact of RP on well-being. Audiologists valued RP activities completed as students and suggested ways to continue the use of RP beyond student years.
Tripartite symbiosis of bacterial communities, ectomycorrhizal fungi and invasive pine.
(2023) Thakur, Vanita
The aim of my thesis was to investigate the bacterial communities associated with ectomycorrhizal fungi and invasive trees and their functional significance.
I began my research by collecting the sporocarps of Suillus luteus across P. contorta density gradient. I used 16SrRNA gene metabarcoding to identify bacterial communities from the sporocarps. I found that increasing pine density results in the substantial loss of bacterial alpha diversity in the sporocarps of S. luteus across pine density gradient. Interestingly, I found no change in beta diversity with pine density. This suggests that bacterial taxa in the sporocarps of S. luteus are being lost at random, rather than some sort of filtering which would result in the homogenisation of bacterial communities.
To further understand the bacterial communities associated with ectomycorrhizal fungi, I investigated the bacterial communities in ectomycorrhizal roots along the same pine density gradient. I identified the fungus on each root with Sanger sequencing and used 16SrRNA gene metabarcoding again to identify bacterial communities. First, I analysed the bacterial communities in the roots which were colonised by Suillus spp. To do this analysis I included all the 11 plots from low pine density to high pine density gradient. Secondly, I tested the effect of fungal host on the bacterial communities associated with the roots at high pine density. I did not include the pine density in this analysis because I only found multiple fungal hosts at high pine density. I found that pine density results in the loss of bacterial alpha diversity in ectomycorrhizal roots without any change in the beta diversity. This implies that loss of bacterial alpha diversity associated with ectomycorrhizal fungi are non-directional and not species specific. Furthermore, this confirms that aboveground (sporocarp) and belowground (roots) bacterial communities associated with ectomycorrhizal fungi responds in the same way to pine density.
This research showed that bacterial communities associated with ectomycorrhizal fungi responds to pine density. Further to test the functional capabilities of bacterial communities associated with ectomycorrhizal fungi, Chapter 3 investigated the enzyme activities associated with the ectomycorrhizal root and examined the potential drivers (biotic and abiotic) of the enzyme activities of ectomycorrhizal fungi. To examine the effect of biotic factors on the enzyme activities of ectomycorrhizal roots, I investigated the bacterial and fungal communities associated with ectomycorrhizal roots. I used 16SrRNA gene metabarcoding to identify bacterial communities from the ectomycorrhizal roots. Further, to identify fungal communities associated with the ectomycorrhizal roots, I amplified the ITS2 region for the fungi. The potential root tip enzyme activities were measured by using the microplate method. I found no evidence that bacteria affect the enzymatic activities of the ectomycorrhizal roots. However, I found that pine density controlled hydrolytic enzyme via nutrients (abiotic) while oxidative enzymes are correlated to fungi (biotic).
In this study, I found that pine invasion results in the loss of bacterial diversity associated with ectomycorrhizal fungi and the similar patterns has been seen in case of the ectomycorrhizal roots sampled from the greenhouse soil.
Similarly, pine invasion results in the loss of overall fungal diversity in the greenhouse roots which is similar to the patterns observed in actual pine plots (Sapsford et al., 2022). This study indicates that short term pine legacies persist in the environment even after the removal of the pine. This study also increase the knowledge of bacterial communities associated with ectomycorrhizal fungi in pine invaded environments.
The sense of copresence in a job interview environment supported by an augmented reality device.
(2024) Figueroa , Felipe
Within an organization, personnel recruitment is a critical activity in the human resources strategy. Job interviews are considered one of the most widely used recruitment methods; however, the evolution that this type of method has undergone over time, especially with the use of new technology, has drawn the attention of researchers in the field of human interface technology. One of the disadvantages of e-recruitment, as the new technological tools of the recruitment process are known, is the negative reactions that the use of technological tools generates in the interviewees.
Augmented reality (AR) has stood out for its use in the industrial and health fields thanks to the display of virtual information in the real world. If we think that the use of this tool could be massified to other work contexts, such as personnel selection, and on the other hand, we take into account the adverse responses that this technology could have on the interviewees, the study of these responses is then relevant. In order to know these responses, exploratory and experimental research has been conducted, grouping the participants in two contexts: one under conditions of interaction with AR technology and the other without such support.
The results of this research show the ability of participants to perceptually isolate a possibly new stimulus (the AR headset) and focus their attention on the interview questions. On the other hand, the importance of the quality of the sustained rapport between interviewer and interviewee is also evidenced as an element that eliminates the theoretical barrier that the use of an augmented reality device could mean.
The effect of people noise on perceived tranquillity.
(2024) Braund, Kea
Increasing urbanisation raises concern about the increase of anthropogenic noise in urban areas, and
its impact on surrounding people and associated tranquillity. Consequently, the positive effects and
importance of preserving tranquillity in urban spaces is valuable. Previous studies have led to the
formation of the Tranquillity Rating Prediction Tool (TRAPT), as a way of assessing the tranquillity of
spaces, ranging from wilderness areas to suburban parks (Watts, et al., 2020; Watts, Miah, &
Pheasant, 2013). Through the use of TRAPT, insight has been gained into the impact of various noise
sources on people (Nicholls, 2017; Watts et al, 2020; Watts, Pheasant, & Horoshenkov, 2011).
However, the disturbance of people noise on tranquillity levels in a residential setting has not been
investigated and established through the use of TRAPT.
This study investigated the effect of people noise on tranquillity, determined using a typical
residential garden setting for the New Zealand (NZ) population. Previous studies using TRAPT in
urban spaces have been based in the United Kingdom (UK), and Hong Kong, as well as NZ (Pearse et
al., 2013; Watts & Marafa, 2017). This study aims to validate TRAPT for use in predicting tranquillity
ratings with people noise for the NZ population. The study extends previous research by focussing
on urban areas. The exploration of people noise and its impact on tranquillity is important to provide
an appropriate means of regulating noise in various settings – rural, urban and city areas.
Recordings of a range of anthropogenic noises were collected and edited into tracks for
participants to listen and rate. Visual stimulus of a residential garden was paired with the tracks to
imitate the desired setting. Participants rated their level of tranquillity after the presentation of each
sound stimulus. A comparison was made between the tranquillity rating (TR) of participants and the
TRAPT predictions. It was expected that the higher the people noise level the lower the perceived
tranquillity. The findings of this study followed this hypothesis, with the TR increasing as sound level
(LAeq) decreased. The perceived tranquillity did not differ from that predicted ratings using TRAPT.
This research has a range of real-world applications, particularly in assessing the effect of people
noise on the level of tranquillity in urban and recreational settings.