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Research papers, The University of Auckland Library

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

Research papers, University of Canterbury Library

This research investigates the validation of simulated ground motions on complex structural systems. In this study, the seismic responses of two buildings are compared when they are subjected to as-recorded ground motions and simulated ones. The buildings have been designed based on New Zealand codes and physically constructed in Christchurch, New Zealand. The recorded ground motions are selected from 40 stations database of the historical 22 Feb. 2011 Christchurch earthquake. The Graves and Pitarka (2015) methodology is used to generate the simulated ground motions. The geometric mean of maximum inter-story drift and peak floor acceleration are selected as the main seismic responses. Also, the variation of these parameters due to record to record variability are investigated. Moreover, statistical hypothesis testing is used to investigate the similarity of results between observed and simulated ground motions. The results indicate a general agreement between the peak floor acceleration calculated by simulated and recorded ground motions for two buildings. While according to the hypothesis tests result, the difference in drift can be significant for the building with a shorter period. The results will help engineers and researchers to use or revise the procedure by using simulated ground motions for obtaining seismic responses.

Research papers, University of Canterbury Library

A number of reverse and strike-slip faults are distributed throughout mid-Canterbury, South Island, New Zealand, due to oblique continental collision. There is limited knowledge on fault interaction in the region, despite historical multi-fault earthquakes involving both reverse and strike-slip faults. The surface expression and paleoseismicity of these faults can provide insights into fault interaction and seismic hazards in the region. In this thesis, I studied the Lake Heron and Torlesse faults to better understand the key differences between these two adjacent faults located within different ‘tectonic domains’. Recent activity and surface expression of the Lake Heron fault was mapped and analysed using drone survey, Structure-from-Motion (SfM) derived Digital Surface Model (DSM), aerial image, 5 m-Digital Elevation Model (DEM), luminescence dating technique, and fold modelling. The results show a direct relationship between deformation zone width and the thickness of the gravel deposits in the area. Fold modelling using fault dip, net slip and gravel thickness produces a deformation zone comparable to the field, indicating that the fault geometry is sound and corroborating the results. This result Is consistent with global studies that demonstrate deposit (or soil thickness) correlates to fault deformation zone width, and therefore is important to consider for fault displacement hazard. A geomorphological study on the Torlesse fault was conducted using SfM-DSM, DEM and aerial images Ground Penetrating Radar (GPR) survey, trenching, and radiocarbon and luminescence dating. The results indicate that the Torlesse fault is primarily strike-slip with some dip slip component. In many places, the bedding-parallel Torlesse fault offsets post-glacial deposits, with some evidence of flexural slip faulting due to folding. Absolute dating of offset terraces using radiocarbon dating and slip on fault determined from lateral displacement calculating tool demonstrates the fault has a slip rate of around 0.5 mm/year to 1.0 mm/year. The likelihood of multi-fault rupture in the Torlesse Range has been characterised using paleoseismic trenching, a new structural model, and evaluation of existing paleoseismic data on the Porters Pass fault. Identification of overlapping of paleoseismic events in main Torlesse fault, flexural-slip faults and the Porters Pass fault in the Torlesse Range shows the possibility of distinct or multi-fault rupture on the Torlesse fault. The structural connectivity of the faults in the Torlesse zone forming a ‘flower structure’ supports the potential of multi-fault rupture. Multi-fault rupture modelling carried out in the area shows a high probability of rupture in the Porters Pass fault and Esk fault which also supports the co-rupture probability of faults in the region. This study offers a new understanding of the chronology, slip distribution, rupture characteristics and possible structural and kinematic relationship of Lake Heron fault and Torlesse fault in the South Island, New Zealand.

Research papers, University of Canterbury Library

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.

Research papers, University of Canterbury Library

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.

Research papers, University of Canterbury Library

Rock mass defect controlled deep-seated landslides are widespread within the deeply incised landscapes formed in Tertiary soft rock terrain in New Zealand. The basal failure surfaces of deep-seated slope failures are defined by thin, comparatively weak and laterally continuous bedding parallel layers termed critical stratigraphic horizons. These horizons have a sedimentary origin and have typically experienced some prior tectonically induced shear displacement at the time of slope failure. The key controls on the occurrence and form of deep-seated landslides are considered in terms of rock mass defect properties and tectonic and climatic forcing. The selection of two representative catchments (in southern Hawke's Bay and North Canterbury) affected by tectonic and climatic forcing has shown that the spatial and temporal initiation of deep-seated bedrock landslides in New Zealand Tertiary soft rock terrain is a predictable rather than a stochastic process; and that deep-seated landslides as a mass wasting process have a controlling role in landscape evolution in many catchments formed in Tertiary soft rock terrain. The Ella Landslide in North Canterbury is a deep-seated (~85 m) translational block slide that has failed on a 5 - 10 mm thick, kaolinite-rich, pre-sheared critical stratigraphic horizon. The residual strength of this sedimentary horizon, (C'R 2.6 - 2.7 kPa, and Ѳ'R = 16 - 21°), compared to the peak strength of the dominant lithology (C' = 176 kPa, and Ѳ' = 37°) defines a high strength contrast in the succession, and therefore a critical location for the basal failure surface of deep-seated slope failures. The (early to mid Holocene) Ella Landslide debris formed a large landslide dam in the Kate Stream catchment and this has significantly retarded rates of mass wasting in the middle catchment. Numerical stability analysis shows that this slope failure would have most likely required the influence of earthquake induced strong ground motion and the event is tentatively correlated to a Holocene event on the Omihi Fault. The influence of this slope failure is likely to affect the geomorphic development of the catchment on a scale of 10⁴ - 10⁵ years. In deeply incised catchments at the southeastern margin of the Maraetotara Plateau, southern Hawke's Bay, numerous widespread deep-seated landslides have basal failure surfaces defined by critical stratigraphic horizons in the form of thin « 20 mm) tuffaceous beds in the Makara Formation flysch (alternating sandstone and mudstone units). The geometry of deep-seated slope failures is controlled by these regularly spaced (~70 m), very weak critical stratigraphic horizons (C'R 3.8 - 14.2 kPa, and Ѳ'R = 2 - 5°), and regularly spaced (~45 m) and steeply dipping (-50°) critical conjugate joint/fault sets, which act as slide block release surfaces. Numerical stability analysis and historical precedent show that the temporal initiation of deep-seated landslides is directly controlled by short term tectonic forcing in the form of periodic large magnitude earthquakes. Published seismic hazard data shows the recurrence interval of earthquakes producing strong ground motions of 0.35g at the study site is every 150 yrs, however, if subduction thrust events are considered the level of strong ground motion may be much higher. Multiple occurrences of deep-seated slope failure are correlated to failure on the same critical stratigraphic horizon, in some cases in three adjacent catchments. Failure on multiple critical stratigraphic horizons leads to the development of a "stepped" landscape morphology. This slope form will be maintained during successive accelerated stream incision events (controlled by long term tectonic and climatic forcing) for as long as catchments are developing in this specific succession. Rock mass defect controlled deep seated landslides are controlling catchment head progression, landscape evolution and hillslope morphology in the Hawke's Bay study area and this has significant implications for the development of numerical landscape evolution models of landscapes formed in similar strata. Whereas the only known numerical model to consider deep seated landslides as an erosion process (ZSCAPE) considers them as stochastic in time and space, this study shows that this could not be applied to a landscape where the widespread spatial occurrence of deep-seated landslides is controlled by rock mass defects. In both of the study areas for this project, and by implication in many catchments in Tertiary soft rock terrain, deep-seated landslides controlled by rock mass defect strength, spacing and orientation, and tectonic and climatic forcing have an underlying control on landscape evolution. This study quantifies parameters for the development of numerical landscape evolution models that would assess the role of specific parameters, such as uplift rates, incision rates and earthquake recurrence in catchment evolution in Tertiary soft rock terrain.

Research papers, The University of Auckland Library

Unreinforced masonry (URM) cavity-wall construction is a form of masonry where two leaves of clay brick masonry are separated by a continuous air cavity and are interconnected using some form of tie system. A brief historical introduction is followed by details of a survey undertaken to determine the prevalence of URM cavity-wall buildings in New Zealand. Following the 2010/2011 Canterbury earthquakes it was observed that URM cavity-walls generally suffered irreparable damage due to a lack of effective wall restraint and deficient cavity-tie connections, combined with weak mortar strength. It was found that the original cavity-ties were typically corroded due to moisture ingress, resulting in decreased lateral loadbearing capacity of the cavity-walls. Using photographic data pertaining to Christchurch URM buildings that were obtained during post-earthquake reconnaissance, 252 cavity-walls were identified and utilised to study typical construction details and seismic performance. The majority (72%, 182) of the observed damage to URM cavity-wall construction was a result of out-of-plane type wall failures. Three types of out-of-plane wall failure were recognised: (1) overturning response, (2) one-way bending, and (3) two-way bending. In-plane damage was less widely observed (28%) and commonly included diagonal shear cracking through mortar bed joints or bricks. The collected data was used to develop an overview of the most commonly-encountered construction details and to identify typical deficiencies in earthquake response that can be addressed via the selection and implementation of appropriate mitigation interventions. http://www.journals.elsevier.com/structures

Research papers, University of Canterbury Library

The 2015 New Zealand strong-motion database provides a wealth of new strong motion data for engineering applications. An important component of this database is the compilation of new site metadata, describing the soil conditions and site response at GeoNet strong motion stations. We have assessed and compiled four key site parameters for the ~460 GeoNet stations that recorded significant historical ground motions. Parameters include: site classification (NZS1170.5), Vs30, fundamental site period (Tsite) and depth to bedrock (Z1.0, i.e. depth to material with Vs > 1000 m/s). In addition, we have assigned a quality estimate (Quality 1 – 3) to these parameters to provide a qualitative estimate of the uncertainty. New highquality Tsite estimates have largely been obtained from newly available HVSR amplification curves and spectral ratios from inversion of regional strong motion data that has been reconciled with available geological information. Good quality Vs30 estimates, typically in urban centres, have also been incorporated following recent studies. Where site-specific measurements of Vs30 are not available, Vs30 is estimated based on surface geology following national Vs30 maps. New Z1.0 values have been provided from 3D subsurface models for Canterbury and Wellington. This database will be used in efforts to guide development and testing of new and existing ground motion prediction models in New Zealand. In particular, it will allow reexamination of the most important site parameters that control and predict site response in a New Zealand setting. Furthermore, it can be used to provide information about suitable rock reference sites for seismological research, and as a guide to site-specific references in the literature. We discuss compilation of the database, preliminary insights so far, and future directions.

Research papers, The University of Auckland Library

During many years the analysis of some geophysical results of Charles Darwin was being carried out in Department. Darwin has connected almost 200 years ago results of catastrophic earthquakes with vertical movement of a surface of the Earth. Usually this movement less horizontal movement and its influence on destruction of cities is not considered. Earthquake hazard assessment studies were focused usually on the horizontal ground motion. Effects of the strong vertical motion were not, practically, discussed. The margins of safety against gravity-induced static vertical forces in constructed buildings usually provide adequate resistance to dynamic forces induced by the vertical acceleration during an earthquake. However, the earthquake in Christchurch is an example of the vertical seismic shock . The earthquake magnitude was rather small - nearby 6.3. However, the result was catastrophic. The same took place in 1835. It allowed to Darwin to formulate a few great ideas. Charles Darwin has explained qualitatively results of an interaction of huge seismic waves with volcanoes and the nature of volcanism and seismicity of our planet. These important data of Charles Darwin became very actual recently. It is possible to tell also the same about tsunami and extreme ocean waves described by Charles Darwin. Therefore this data were analyzed using modern mechanics, mathematics and physics in Department. In particular, the theory of catastrophic waves was developed based on Darwin's data. The theory tried to explain occurrence, evolution and distribution the catastrophic waves in various natural systems, since atoms, oceans, surfaces of the Earth and up to the very early Universe. Some results of the research were published in prestigious magazines. Later they were presented in two books devoted to Charles Darwin's anniversary (2009). Last from them was published in Russian (2011). We give here key ideas of this research which is a part of interdisciplinary researches of Department. Some ideas are discussed. Not less important purpose is very short historical review of some researches of Darwin. In particular, we underline Darwin' priority in the formulation of the bases of Dynamics Earth.

Research papers, University of Canterbury Library

Documenting earthquake-induced ground deformation is significant to assess the characteristics of past and contemporary earthquakes and provide insight into seismic hazard. This study uses airborne light detection and ranging (LiDAR) and conducts multi-disciplinary field techniques to document the surface rupture morphology and evaluate the paleoseismicity and seismic hazard parameters of the Hurunui segment of the Hope Fault in the northern South Island of New Zealand. It also documents and evaluates seismically induced features and ground motion characteristics of the 2010 Darfield and 2011 Christchurch earthquakes in the Port Hills, south of Christchurch. These two studies are linked in that they investigate the near-field coseismic features of large (Mw ~7.1) earthquakes in New Zealand and produce data for evaluating seismic hazards of future earthquakes. In the northern South Island of New Zealand, the Australian-Pacific plate boundary is characterised by strike-slip deformation across the Marlborough Fault System (MFS). The ENE-striking Hope Fault (length: ~230 km) is the youngest and southernmost fault in the MFS, and the second fastest slipping fault in New Zealand. The Hope Fault is a major source of seismic hazard in New Zealand and has ruptured (in-part) historically in the Mw 7.1 1888 Amuri earthquake. In the west, the Hurunui segment of the Hope Fault is covered by beech forest. Hence, its seismic hazard parameters and paleoearthquake chronology were poorly constrained and it was unknown whether the 1888 earthquake ruptured this segment or not and if so, to what extent. Utilising LiDAR and field data, a 29 km-long section of the Hurunui segment of the Hope Fault is mapped. LiDAR-mapping clearly reveals the principal slip zone (PSZ) of the fault and a suite of previously unrecognised structures that form the fault deformation zone (FDZ). FDZ width measurements from 415 locations reveal a spatially-variable, active FDZ up to ~500 m wide with an average width of 200 m. Kinematic analysis of the fault structures shows that the Hurunui segment strikes between 070° and 075° and is optimally oriented for dextral strike-slip within the regional stress field. This implies that the wide FDZ observed is unlikely to result from large-scale fault mis-orientation with respect to regional stresses. The analysis of FDZ width indicates that it increases with increased hanging wall topography and increased topographic relief suggesting that along-strike topographic perturbations to fault geometry and stress states increase fault zone complexity and width. FDZ width also increases where the tips of adjacent PSZ strands locally vary in strike, and where the thickness of alluvial deposits overlying bedrock increases. LiDAR- and photogrammetrically-derived topographic mapping indicates that the boundary between the Hurunui and Hope River segments is characterised by a ~850-m-wide right stepover and a 9º-14° fault bend. Paleoseismic trenching at Hope Shelter site reveals that 6 earthquakes occurred at A.D. 1888, 1740-1840, 1479-1623, 819-1092, 439-551, and 373- 419. These rupture events have a mean recurrence interval of ~298 ± 88 yr and inter-event times ranging from 98 to 595 yrs. The variation in the inter-event times is explained by (1) coalescing rupture overlap from the adjacent Hope River segment on to the Hurunui segment at the study site, (2) temporal clustering of large earthquakes on the Hurunui segment, and/or (3) ‘missing’ rupture events. It appears that the first two options are more plausible to explain the earthquake chronologies and rupture behaviour on the Hurunui segment, given the detailed nature of the geologic and chronologic investigations. This study provides first evidence for coseismic multi-segment ruptures on the Hope Fault by identifying a rupture length of 44-70 km for the 1888 earthquake, which was not confined to the Hope River segment (primary source for the 1888 earthquake). LiDAR data is also used to identify and measure dextral displacements and scarp heights from the PSZ and structures within the FDZ along the Hurunui segment. Reconstruction of large dextrally-offset geomorphic features shows that the vertical component of slip accounts for only ~1% of the horizontal displacements and confirms that the fault is predominantly strike-slip. A strong correlation exists between the dextral displacements and elevations of geomorphic features suggesting the possibility of age correlation between the geomorphic features. A mean single event displacement (SED) of 3.6 ± 0.7 m is determined from interpretation of sets of dextral displacements of ≤ 25 m. Using the available surface age data and the cumulative dextral displacements from Matagouri Flat, McKenzie Fan, Macs Knob and Hope River sites, and the mean SED, a mean slip rate of 12.2 ± 2.4 mm/yr, and a mean recurrence interval of ~320 ± 120 yr, and a potential earthquake magnitude of Mw 7.2 are determined for the Hurunui segment. This study suggests that the fault slip rate has been constant over the last ~15000 yr. Strong ground motions from the 2010 Darfield (Canterbury) earthquake displaced boulders and caused ground damage on some ridge crests in the Port Hills. However, the 2011 Christchurch earthquake neither displaced boulders nor caused ground damage at the same ridge crests. Documentation of locations (~400 m a.s.l.), lateral displacements (8-970 cm), displacement direction (250° ± 20°) of displaced boulders, in addition to their hosting socket geometries (< 1 cm to 50 cm depth), the orientation of the ridges (000°-015°) indicate that boulders have been displaced in the direction of instrumentally recorded transient peak ground horizontal displacements nearby and that the seismic waves have been amplified at the study sites. The co-existence of displaced and non-displaced boulders at proximal sites suggests small-scale ground motion variability and/or varying boulder-ground dynamic interactions relating to shallow phenomena such as variability in soil depth, bedrock fracture density and/or microtopography on the bedrock-soil interface. Shorter shaking duration of the 2011 Christchurch event, differing frequency contents and different source characteristics were all factors that may have contributed to generating circumstances less favourable to boulder displacement in this earthquake. Investigating seismically induced features, fault behaviour, site effects on the rupture behaviour, and site response to the seismic waves provides insights into fault rupture hazards.

Research papers, University of Canterbury Library

The Amuri Earthquake of September 1, 1888 (magnitude M = 6.5 to 6.8) occurred on the Hope River Segment of the Hope Fault west of Hanmer Plains. The earthquake was felt strongly in North Canterbury and North Westland and caused considerable property damage and landsliding in the Lower Hope Valley. However, damage reports and the spatial distribution of felt intensities emphasize extreme variations in seismic effects over short distances, probably due to topographic focusing and local ground conditions. Significant variations in lateral fault displacement occurred at secondary fault segment boundaries (side-steps and bends in the fault trace) during the 1888 earthquake. This historical spatial variation in lateral slip is matched by the Late Quaternary geomorphic distribution of slip on the Hope River Segment of the Hope Fault. Trenching studies at two sites on the Hope Fault have also identified evidence for five pre-historic earthquakes of similar magnitude to the 1888 earthquake and an average recurrence interval of 134 ± 27 years between events. Magnitude estimates for the 1888 earthquake are combined with a. strong ground motion attenuation expression to provide an estimate of potential ground accelerations in Amuri District during-future earthquakes on the Hope River Segment of the Hope Fault. The predicted acceleration response on bedrock sites within 20 km of the epicentral region is between 0.23 g and 0.34 g. The close match between the historic, inferred pre-historic and geomorphic distribution of lateral slip indicates that secondary fault segmentation exerts a strong structural control on rupture propagation and the expression of fault displacement at the surface. In basement rocks at depth the spatial variations in slip are inferred to be distributed within zones of pervasive cataclastic shear, on either side of the fault segment boundaries. The large variations in surface displacement across fault segment boundaries means that one must know the geometry of the fault in order to evaluate slip-rates calculated from individual locations. The average Late Quaternary slip-rate on the Hope Fault at Glynn Wye Station is between 15.5 mm/yr and 18.25 mm/yr and the rate on the subsidiary Kakapo Fault is between 5.0 mm/yr and 7.5 mm/yr. These rates have been determined from sites which are relatively free of structural complication.

Videos, NZ On Screen

Early Days Yet, directed by Shirley Horrocks, is a full-length documentary about New Zealand poet Allen Curnow, made in the last months of his life. The poet talks about his life and work, and visits the places of some of his most important poems. It includes interviews with other New Zealand poets about Curnow's significance as an advocate for New Zealand poetry. As Curnow famously mused in front of a moa skeleton displayed in Canterbury Museum: "Not I, some child, born in a marvellous year / Will learn the trick of standing upright here."

Research papers, University of Canterbury Library

Exploring women’s experiences of entering, working in, or leaving the Christchurch construction industry between 2010 and 2018 led to the creation of the theory of “deferential tailoring.” Deferential tailoring explains how women shape their responses to industry conditions as an intentional behavioural adjustment process. Most importantly, this theory provides insight into women’s unseen efforts to build positive workplace relationships, their capability to advance, and challenges to existing views of gender roles in this context. Research on women in construction focusses primarily on identifying and explaining barriers that impact on women’s entry, progression, and retention in the industry. There is an absence of process studies that explain the actions women take to manage industry conditions in business-as-usual, let alone post-disaster contexts. In the eight years following the 2010 Canterbury (New Zealand) earthquakes, rapid changes to the construction industry meant women had unprecedented access and new opportunities in this historically male-dominated domain. This setting provided a unique context within which to investigate how women respond to industry opportunities and challenges. The aim of this interpretive research was to construct a response theory, particular to women working in the Christchurch construction industry. Applying a constructivist grounded theory approach, theoretical sampling, coding and memo writing allowed for the collection and comparative analysis of 36 semi-structured interviews conducted with women working in a cross-section of industry occupations. Three inter- related categories were built: capitalising on opportunity, building capability and token tolerance, which together constitute the deferential tailoring process. Akin to building an invisible glass scaffold, women intentionally regulate their behaviours to successfully seize opportunities and manage social challenges. In building this scaffold, women draw heavily on personal values and positive, proactive attributes as a response to industry conditions. In contrast to previous research, which suggests that women conform to the male-dominated norms of the industry, the theory of deferential tailoring proposes that women are prepared to regulate their behaviour to address the gendered norms that impact on their work experiences. This research contributes towards an evolving body of knowledge that aims to understand how women’s entry into the construction industry, retention, and workplace relationships can be improved. By expanding the view of how women respond to industry conditions over time, this research has generated knowledge that addresses gaps in construction industry literature relating to the management of coping strategies, capitalising on opportunities, and building positive workplace relationships. Knowledge and concepts generated from this research could be integrated into recruitment and training programmes to enhance women’s professional development, shift perceptions of women’s work, and address cultural norms that impact on women’s retention in the construction industry.

Research Papers, Lincoln University

Mixed conifer, beech and hardwood forests are relatively common in Aotearoa/New Zealand, but are not well studied. This thesis investigates the coexistence, regeneration dynamics and disturbance history of a mixed species forest across an environmental gradient of drainage and soil development in north Westland. The aim was to investigate whether conifers, beech and non-beech hardwood species were able to coexist on surfaces that differed in their underlying edaphic conditions, and if so to understand the mechanisms that influenced their regeneration on both poorly drained and well drained soils. The site selected was an area of high tree species diversity on a lowland 0.8 km² post-glacial terrace at the base of Mount Harata in the Grey River Valley. My approach was to use forest stand history reconstruction at two spatial scales: an intensive within-plot study of stand dynamics (chapter 1) and a whole-landform approach (chapter 2) that examined whether the dynamics identified at the smaller within-plot scale reflected larger patterns across the terrace. In chapter 1, three large permanent plots (0.3-0.7 ha) were placed at different points along the drainage gradient, one plot situated in each of the mainly well-drained, poorly drained and very poorly drained areas along the terrace. Information was gathered on species age and size structures, spatial distributions of tree ages, species interactions, microsite establishment preferences, patterns of stand mortality, and disturbance history in each plot. There were differences in stand structure, composition and relative abundance of species found between the well drained plot and the two poorer drained plots. On the well drained site conifers were scarce, the beeches Nothofagus fusca and N. menziesii dominated the canopy, and in the subcanopy the hardwood species Weinmannia racemosa and Quintinia acutifolia were abundant. As drainage became progressively poorer, the conifers Dacrydium cupressinum and Dacrycarpus dacrydioides became more abundant and occupied the emergent tier over a beech canopy. The hardwoods W. racemosa and Q. acutifolia became gradually less abundant in the subcanopy, whereas the hardwood Elaeocarpus hookerianus became more so. In the well drained plot, gap partitioning for light between beeches and hardwoods enabled coexistence in response to a range of different sized openings resulting from disturbances of different extent. In the two more poorly drained plots, species also coexisted by partitioning microsite establishment sites according to drainage. There were several distinct periods where synchronous establishment of different species occurred in different plots, suggesting there were large disturbances: c. 100yrs, 190-200 yrs, 275-300 yrs and 375-425 yrs ago. Generally after the same disturbance, different species regenerated in different plots reflecting the underlying drainage gradient. However, at the same site after different disturbances, different sets of species regenerated, suggesting the type and extent of disturbances and the conditions left behind influenced species regeneration at some times but not others. The regeneration of some species (e.g., N. fusca in the well-drained plot, and Dacrydium in the poorer drained plots) was periodic and appeared to be closely linked to these events. In the intervals between these disturbances, less extensive disturbances resulted in the more frequent N. menziesii and especially hardwood regeneration. The type of tree death caused by different disturbances favoured different species, with dead standing tree death favouring the more shade-tolerant N. menziesii and hardwoods, whereas uprooting created a mosaic of microsite conditions and larger gap sizes that enabled Dacrycarpus, N. fusca and E. hookerianus to maintain themselves in the poorly drained areas. In chapter 2, 10 circular plots (c. 0.12 ha) were placed in well drained areas and 10 circular plots (c. 0.2 ha) in poorly drained plots to collect information on species population structures and microsite preferences. The aims were to reconstruct species' regeneration responses to a range of disturbances of different type and extent across the whole terrace, and to examine whether there were important differences in the effects of these disturbances. At this landform scale, the composition and relative abundances of species across the drainage gradient reflected those found in chapter 1. There were few scattered conifers in well drained areas, despite many potential regeneration opportunities created from a range of different stand destroying and smaller scale disturbances. Three of the four periods identified in chapter 1 reflected distinct terrace-wide periods of regeneration 75-100 yrs, 200-275 yrs and 350-450 yrs ago, providing strong evidence of periodic large, infrequent disturbances that occurred at intervals of 100-200 yrs. These large, infrequent disturbances have had a substantial influence in determining forest history, and have had long term effects on forest structure and successional processes. Different large, infrequent disturbances had different effects across the terrace, with the variability in conditions that resulted enabling different species to regenerate at different times. For example, the regeneration of distinct even-aged Dacrydium cohorts in poorly drained areas was linked to historical Alpine Fault earthquakes, but not to more recent storms. The variation in the intensity of different large, infrequent disturbances at different points along the environmental drainage gradient, was a key factor influencing the scale of impacts. In effect, the underlying edaphic conditions influenced species composition along the drainage gradient and disturbance history regulated the relative abundances of species. The results presented here further emphasise the importance of large scale disturbances as a mechanism that allows coexistence of different tree species in mixed forest, in particular for the conifers Dacrydium, Dacrycarpus and the beech N. fusca, by creating much of the environmental variation to which these species responded. This study adds to our understanding of the effects of historical earthquakes in the relatively complex forests of north Westland, and further illustrates their importance in the Westland forest landscape as the major influential disturbance on forest pattern and history. These results also further develop the 'two-component' model used to describe conifer/angiosperm dynamics, by identifying qualitative differences in the impacts of different large, infrequent disturbances across an environmental gradient that allowed for coexistence of different species. In poorer drained areas, these forests may even be thought of as 'three-component' systems with conifers, beeches and hardwoods exhibiting key differences in their regeneration patterns after disturbances of different type and extent, and in their microsite preferences.

Research papers, University of Canterbury Library

The Porter's Pass-Amberley Fault Zone (PPAFZ) is a complex zone of anastomosing faults and folds bounding the south-eastern edge of the transition from subducting Pacific Plate to continental collision on the Australia Plate boundary. This study combines mapping of a 2000 km2 zone from the Southern Alps northeast to the coast near Amberley, 40 km north of metropolitan Christchurch, with an analysis of seismicity and a revision of regional seismic hazard. Three structural styles: 1) a western strike-slip, and 2) a more easterly thrust and reverse domain, pass into 3) a northwest verging fold belt on the northern Canterbury Plains, reflecting the structural levels exposed and the evolving west to east propagation. Basal remnants of a Late Cretaceous-Cenozoic, largely marine sedimentary cover sequence are preserved as outliers that unconformably overlie Mesozoic basement (greywacke and argillite of the Torlesse terrain) in the mountains of the PPAFZ and are underlain by a deeply leached zone which is widely preserved. Structure contouring of the unconformity surface indicates maximum, differential uplift of c.2600 m in the southwest, decreasing to c.1200 m in the coastal fold belt to the northeast. Much lower rates (or reversal) of uplift are evident a few kilometres southeast of the PPAFZ range-front escarpment. The youngest elements of the cover sequence are basement-derived conglomerates of Plio-Pleistocene age preserved on the SE margin. The source is more distant than the intervening mountains of the PPAFZ, probably from the Southern Alps, to the west and northwest. The absence of another regional unconformity on Mesozoic basement, older than Pleistocene, indicates that this uplift is post-Pliocene. Late Pleistocene(<100 kyr) differential uplift rates of c.0.5-2.7 m/kyr from uplifted marine terraces at the east coast, and rates of 2.5-3.3 m/kyr for tectonically-induced river-down cutting further west, suggest that uplift commenced locally during the last 1 Ma, and possibly within the last 0.5 Ma, if average rates are assumed to be uniform over time. Analysis of seismicity, recorded during a 10 week regional survey of micro earthquakes in 1990, identified two seismic zones beneath North Canterbury: 1) a sub-horizontal zone of activity restricted to the upper crust (≤12 km); and 2) a seismic zone in the lower crust (below a ceiling of ≤17 km), that broadens vertically to the north and northwest to a depth of c.40 km, with a bottom edge which dips 10°N and 15°NW, respectively. No events were recorded at depths between 12 km and 17 km, which is interpreted as a relatively aseismic, mid-crustal ductile layer. Marked differences (up to 60°) in the trend of strain axes for events above and below the inferred ductile layer are observed only north of the PPAFZ. A fundamental, north-to-south increase in the Wave-length of major geological structures occurs across the PPAFZ, and is interpreted as evidence that the upper crust beneath the Canterbury Plains is coupled to the lower crust, whereas the upper crust further north is not. Most of the recorded micro earthquakes <12 km deep beneath the PPAFZ have strike-slip mechanisms. It is probable that faults splay upward into the thrusts and folds at the surface as an evolving transpression zone in response to deep shear in basement. There have been no historic surface ruptures of the PPAFZ, but the zone has been characterised historically by frequent small earthquakes. Paleoseismic data (dated landslides and surface ruptures) compiled in this study, indicate a return period of 1500-1900 years between the last two M>7-7.5 earthquakes, and 500-700 years have elapsed since the last. The magnitudes of these events are estimated at c.M7.5, which represents a probable maximum magnitude for the PPAFZ. There are insufficient data to determine whether or not the frequency of large earthquakes conforms to a recognised model of behaviour, but comparison of the paleoseismic data with the historic record of smaller earthquakes, suggests that the magnitudes of the largest earthquakes in this zone are not exponentially distributed. A seismicity model for the PPAFZ (Elder et al., 1991) is reviewed, and a b-value of 1.0 is found to be consistent with the newly acquired paleoseismic data. This b-value reduces the predicted frequency of large earthquakes (M≥7.0) in this zone by a factor of 3.5, while retaining a conservative margin that allows for temporal variations in the frequency of large events and the possibility that the geological database is incomplete, suggesting grounds for revising the hazard model for Christchurch.

Research papers, University of Canterbury Library

Liquefaction of sandy soil has been observed to cause significant damage to infrastructure during major earthquakes. Historical cases of liquefaction have typically occurred in sands containing some portion of fines particles, which are defined as 75μm or smaller in diameter. The effects of fines on the undrained behaviour of sand are not however fully understood, and this study therefore attempts to quantify these effects through the undrained testing of sand mixed with non-plastic fines sourced from Christchurch, New Zealand. The experimental program carried out during this study consisted of undrained monotonic and cyclic triaxial tests performed on three different mixtures of sand and fines: the Fitzgerald Bridge mixture (FBM), and two Pinnacles Sand mixtures (PSM1 and PSM2). The fines content of each host sand was systematically varied up to a maximum of 30%, with all test specimens being reconstituted using moist tamping deposition. The undrained test results from the FBM soils were interpreted using a range of different measures of initial state. When using void ratio and relative density, the addition of fines to the FBM sand caused more contractive behaviour for both monotonic and cyclic loadings. This resulted in lower strengths at the steady state of deformation, and lower liquefaction resistances. When the intergranular void ratio was used for the interpretation, the effect of additional fines was to cause less contractive response in the sand. The state parameter and state index were also used to interpret the undrained cyclic test results – these measures suggested that additional fines caused less contractive sand behaviour, the opposite to that observed when using the void ratio. This highlighted the dependency on the parameter chosen as a basis for the response comparison when determining the effects of fines, and pointed out a need to identify a measure that normalizes such effects. Based on the FBM undrained test results and interpretations, the equivalent granular void ratio, e*, was identified from the literature as a measure of initial state that normalizes the effects of fines on the undrained behaviour of sand up to a fines content of 30%. This is done through a parameter within the e* definition termed the fines influence factor, b, which quantifies the effects of fines from a value of zero (no effect) to one (same effect as sand particles). The value of b was also determined to be different when interpreting the steady state lines (bSSL) and cyclic resistance curves (bCR) respectively for a given mixture of sand and fines. The steady state lines and cyclic resistance curves of the FBM soils and a number of other sand-fines mixtures sourced from the literature were subsequently interpreted using the equivalent granular void ratio concept, with bSSL and bCR values being back-calculated from the respective test data sets. Based on these interpretations, it was concluded that e* was conceptually a useful parameter for characterizing and quantifying the effects of fines on the undrained behaviour of sand, assuming the fines influence factor value could be derived. To allow prediction of the fines influence factor values, bSSL and bCR were correlated with material and depositional properties of the presented sand-fines mixtures. It was found that as the size of the fines particles relative to the sand particles became smaller, the values of bSSL and bCR reduced, indicating lower effect of fines. The same trend was also observed as the angularity of the sand particles increased. The depositional method was found to influence the value of bCR, due to the sensitivity of cyclic loading to initial soil fabric. This led to bSSL being used as a reference for the effect of fines, with specimens prepared by moist tamping having bCR > bSSL, and specimens prepared by slurry deposition having bCR < bSSL. Finally the correlations of the fines influence factor values with material and depositional properties were used to define the simplified estimation method – a procedure capable of predicting the approximate steady state lines and cyclic resistance curves of a sand as the non-plastic fines content is increased up to 30%. The method was critically reviewed based on the undrained test results of the PSM1 and PSM2 soils. This review suggested the method could accurately predict undrained response curves as the fines content was raised, based on the PSM1 test results. It also however identified some key issues with the method, such as the inability to accurately predict the responses of highly non-uniform soils, a lack of consideration for the entire particle size distribution of a soil, and the fact the errors in the prediction of bSSL carry through into the prediction of bCR. Lastly some areas of further investigation relating to the method were highlighted, including the need to verify the method through testing of sandy soils sourced from outside the Christchurch area, and the need to correlate the value of bCR with additional soil fabrics / depositional methods.

Research papers, University of Canterbury Library

Following the Mw 6.2 Christchurch Earthquake on 22 February 2011, extensive ground cracking in loessial soils was reported in some areas of the Port Hills, southeast of central Christchurch. This study was undertaken to investigate the mechanisms of earthquake-induced ground damage on the eastern side of the Hillsborough Valley. A zone of extensional cracking up to 40m wide and 600m long was identified along the eastern foot-slope, accompanied by compression features and spring formation at the toe of the slope. An engineering geological and geomorphological model was developed for the eastern Hillsborough Valley that incorporates geotechnical investigation data sourced from the Canterbury Geotechnical Database (CGD), the findings of trenching and seismic refraction surveying carried out for this research, and interpretation of historical aerial photographs. The thickness and extent of a buried peat swamp at the base of the slope was mapped, and found to coincide with significant compression features. Ground cracking was found to have occurred entirely within loess-colluvium and to follow the apices of pre-1920s tunnel-gully fan debris at the southern end of the valley. The ground-cracking on the eastern side of the Hillsborough Valley is interpreted to have formed through tensile failure of the loess-colluvium. Testing was carried out to determine the tensile strength of Port Hills loess colluvium as a function of water content and density, in order to better understand the occurrence and distribution of the observed ground cracking. A comprehensive review of the soil tensile strength testing literature was undertaken, from which a test methodology was developed. Results show remoulded loess-colluvium to possess tensile strength of 7 - 28 kPa across the range of tested moisture contents (10-15%) and dry densities (1650-1900kg/m3). A positive linear relationship was observed between tensile strength and dry density, and a negative linear relationship between moisture content and tensile strength. The observed ground damage and available geotechnical information (inclinometer and piezometer records provided by the Earthquake Commission) were together used to interpret the mechanism(s) of slope movement that occurred in the eastern Hillsborough Valley. The observed ground damage is characteristic of translational movement, but without the development of lateral release scarps, or a basal sliding surface - which was not located during drilling. It is hypothesised that shear displacement has been accommodated by multiple slip surfaces of limited extent within the upper 10m of the slope. Movement has likely occurred within near-saturated colluvial units that have lost strength during earthquake shaking. The eastern Hillsborough Valley is considered to be an ‘incipient translational slide’, as both the patterns of damage and shearing are consistent with the early stages of such slide development. Sliding block analysis was utilised to understand how the eastern Hillsborough Valley may perform in a future large magnitude earthquake. Known cumulative displacements of ~0.3m for eastern Hillsborough Valley during the 2010-2011 Canterbury Earthquake Sequence were compared with modelled slope displacements to back-analyse a lower-bound yield acceleration of 0.2 - 0.25g. Synthetic broadband modelling for future Alpine and Hope Fault earthquakes indicates PGAs of approximately 0.08g for soil sites in the Christchurch area, as such, slope movement is unlikely to be reactivated by an Alpine Fault or Hope Fault earthquake. This does not take into account the possible role of strength loss due to excess pore pressure that may occur during these future events.

Research papers, Victoria University of Wellington

<strong>Sea level rise is one consequence of Earth’s changing climate. Century-long tide gauge records show that global-mean sea-level rise reached 11-16 cm during the twentieth century at a mean rate of 1.2 mm/y. Today, the average rate of global-mean sea-level rise is higher at 3-4 mm/y and is expected to increase in the future. This represents a hazard to low elevation coastal zones worldwide. Yet, before global sea level projections can be used to characterise future coastal flood hazard at a local scale, the effects of tectonics (and other processes) that drive vertical land motion (VLM) must be considered. VLM is defined as the vertical velocity (uplift or subsidence) of the solid surface with respect to the centre of Earth. In this study, new VLM maps are generated over coastal strips in New Zealand, using Sentinel-1 InSAR and GNSS data.</strong>In New Zealand, measuring VLM using InSAR on naturally vegetated or agricultural land is difficult due to signal decorrelation. Along the rural Bay of Plenty coastal strip, I use a persistent-scatterer approach to generate a VLM map from both east-looking ascending and west-looking descending Sentinel-1 data between 2015-2021. Using time-series data over the same time period from a dense network of 20 GNSS sensors, I tie InSAR-derived line-of-sight velocity to the 2014 ITRF reference frame. I test two different methods for measuring VLM and compare the results against GNSS vertical velocity along the Bay of Plenty coast. Best results are achieved by first removing the interpolated horizontal GNSS velocity field from each of the InSAR datasets, before averaging the two VLM estimates. Measured VLM is between -3 and 3 mm/y, with negative values (subsidence) occurring within the low-lying Rangitāiki Plain and Ōpōtiki valley, and uplift across the elevated region west of Matatā.This thesis integrates geomorphological, geological, and historical levelling VLM records with modern satellite datasets to assess VLM across timescales ranging from 10 to 100,000 years at Matatā. Uplift rate has been variable through time, with average uplift over the last 300,000 years of 1 mm/y, 4.5 mm/y since 1720 years, 2 mm/y between 1950-1978, and 10 mm/y between 2004-2011. Previous modelling has shown that the best fit to the 2004-2011 rapid uplift rates is an inflating magmatic source at ~10 km depth beneath Matatā. To reconcile all data, I present a VLM model that consists of short-lived periods (7 years) of rapid uplift (10 mm/y), separated by longer periods (30 years) of lower background uplift (3 mm/y). The episodic nature of VLM at Matatā likely reflects short-lived periods of magmatic intrusion. Episodic VLM characterised by large rates of uplift (10 mm/y) has been seen at Taupō volcano, and other volcanic centers globally. It has been 12 years since the end of the last intrusion episode; this modelling suggest one may expect to observe increased uplift rates at Matatā in the coming decades. Densely populated urban coastal strips are most at risk from the effects of relative sea-level rise. At the same time, anthropogenic activities associated with urbanization, such as groundwater withdrawal, and land reclamation can lead to local land subsidence (LLS), further exacerbating the risk to urban infrastructure. LLS refers to subsidence relative to nearby land area assumed to be stable. In this thesis, I create the first high-resolution (10 m) maps of LLS at six urban coastal strips in New Zealand, with a combined length of 285 km, using Sentinel-1 InSAR data between 2018-2021. This analysis reveals 89% of urban coastal strips are subsiding at rates of -0.5 mm/y or greater, and 11% is subsiding at higher rates of -3.0 mm/y or greater. On average, subsidence is -0.6 to -2.9 mm/y higher at the coastal strip, compared to inland areas occupied by GNSS stations. This analysis also documents highly-localised hotspots of LLS, with subsidence rates of up to -15 mm/y. In Christchurch, rapid and localised subsidence (-8 mm/y) is observed within coastal suburbs New Brighton and Southshore. In most cities, the highest subsidence rates occur on land reclaimed in the early-late twentieth century, and in areas built on Holocene sediment. Time-series analysis of LLS at sites of reclaimed land shows both linear and non-linear rates of deformation over time periods of up to 6-8 years. This thesis highlights the variable exposure to relative sea-level rise of New Zealand coastal strips, and demonstrates that in many cases current rates of VLM should be expected to continue for the next few decades.