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Research papers, University of Canterbury Library

Over 6.3 million waste tyres are produced annually in New Zealand (Tyrewise, 2021), leading to socioeconomic and environmental concerns. The 2010-11 Canterbury Earthquake Sequence inflicted extensive damage to ~6,000 residential buildings, highlighting the need to improve the seismic resilience of the residential housing sector. A cost-effective and sustainable eco-rubber geotechnical seismic isolation (ERGSI) foundation system for new low-rise buildings was developed by the authors. The ERGSI system integrates a horizontal geotechnical seismic isolation (GSI) layer i.e., a deformable seismic energy dissipative filter made of granulated tyre rubber (GTR) and gravel (G) – and a flexible rubberised concrete raft footing. Geotechnical experimental and numerical investigations demonstrated the effectiveness of the ERGSI system in reducing the seismic demand at the foundation level (i.e., reduced peak ground acceleration) (Hernandez et al., 2019; Tasalloti et al., 2021). However, it is essential to ensure that the ERGSI system has minimal leaching attributes and does not result in long-term negative impacts on the environment.

Research papers, University of Canterbury Library

Detailed studies on the sediment budget may reveal valuable insights into the successive build-up of the Canterbury Plains and their modification by Holocene fluvialaction connected to major braided rivers. Additionally, they bear implications beyond these fluvial aspects. Palaeoseismological studies claim to have detected signals of major Alpine Fault earthquakes in coastal environments along the eastern seaboard of the South Island (McFadgen and Goff, 2005). This requires high connectivity between the lower reaches of major braided rivers and their mountain catchments to generate immediate significant sediment pulses. It would be contradictory to the above mentioned hypothesis though. Obtaining better control on sediment budgets of braided rivers like the Waimakariri River will finally add significant value to multiple scientific and applied topics like regional resource management. An essential first step of sediment budget studies Is to systematically map the geomorphology, conventionally in the field and/or using remote-sensing applications, to localise, genetically identify, and classify landforms or entire toposequences of the area being investigated. In formerly glaciated mountain environments it is also indispensable to obtain all available chronological information supporting subsequent investigations.

Research papers, University of Canterbury Library

The affect that the Christchurch Earthquake Sequence(CES) had on Christchurch residents was severe, and the consequences are still being felt today. The Ōtākaro Avon River Corridor (OARC) was particularly impacted, a geographic zone that had over 7,000 homes which needed to be vacated and demolished. The CES demonstrated how disastrous a natural hazard can be on unprepared communities. With the increasing volatility of climate change being felt around the world, considering ways in which communities can reduce their vulnerabilities to natural hazards is vital. This research explores how communities can reduce their vulnerabilities to natural hazards by becoming more adaptable, and in particular the extent to which tiny homes could facilitate the development of adaptive communities. In doing so, three main themes were explored throughout this research: (1) tiny homes, (2) environmental adaptation and (3) community adaptability. To ensure that it is relevant and provides real value to the local community, the research draws upon the local case study of the Riverlution Tiny House Village(RTHV), an innovative community approach to adaptable, affordable, low-impact, sustainable living on margins of land which are no longer suitable for permanent housing. The main findings of the research are that Christchurch is at risk of climate change and natural hazards and it is therefore important to consider ways in which communities can stay intact and connected while adapting to the risks they face. Tiny homes provide an effective way of doing so, as they represent a tangible way that people can take adaptation into their own hands while maintaining a high-quality lifestyle.

Research papers, University of Canterbury Library

The magnitude Mw 6.2 earthquake of February 22nd 2011 that struck beneath the city of Christchurch, New Zealand, caused widespread damage and was particularly destructive to the Central Business District (CBD). The shaking caused major damage, including collapses of structures, and initiated ground failure in the form of soil liquefaction and consequent effects such as sand boils, surface flooding, large differential settlements of buildings and lateral spreading of ground towards rivers were observed. A research project underway at the University of Canterbury to characterise the engineering behaviour of the soils in the region was influenced by this event to focus on the performance of the highly variable ground conditions in the CBD. This paper outlines the methodology of this research to characterise the key soil horizons that underlie the CBD that influenced the performance of important structures during the recent earthquakes, and will influence the performance of the rebuilt city centre under future events. The methodology follows post-earthquake reconnaissance in the central city, a desk study on ground conditions, site selection, mobilisation of a post-earthquake ground investigation incorporating the cone penetration test (CPT), borehole drilling, shear wave velocity profiling and Gel-push sampling followed by a programme of laboratory testing including monotonic and cyclic testing of the soils obtained in the investigation. The research is timely and aims to inform the impending rebuild, with appropriate information on the soils response to dynamic loading, and the influence this has on the performance of structures with various foundation forms.

Research papers, University of Canterbury Library

This report presents an overview of the soil profile characteristics at a number of strong motion station (SMS) sites in Christchurch and its surrounds. An extensive database of ground motion records has been captured by the SMS network in the Canterbury region during the Canterbury earthquake sequence. However in order to comprehensively understand the ground motions recorded at these sites and to be able to relate these motions to other locations, a detailed understanding of the shallow geotechnical profile at each SMS is required. The original NZS1170.5 (SNZ 2004) site subsoil classifications for each SMS site is based on regional geological information and well logs located at varying distances from the site. Given the variability of Christchurch soils, more detailed investigations are required in close vicinity to each SMS to better understand stratigraphy and soil properties, which are important in seismic site response. In this regard, CPT, SPT and borehole data, shear wave velocity (Vs) profiles, and horizontal to vertical spectral ratio measurements (H/V) in close vicinity to the SMS were used to develop representative soil profiles at each site. NZS1170.5 (SNZ 2004) site subsoil classifications were updated using Vs and SPT N60 criteria. Site class E boundaries were treated as a sliding scale rather than as a discrete boundary to account for locations with similar site effects potential, an approach which was shown to result in a better delineation between the site classes. SPT N60 values often indicate a stiffer site class than the Vs data for softer soil sites, highlighting the disparity between the two site investigation techniques. Both SPT N60 and Vs based site classes did not always agree with the original site classifications. This emphasises the importance of having detailed site‐specific information at SMS locations in order to properly classify them. Furthermore, additional studies are required to harmonize site classification based on SPT N60 and Vs. Liquefaction triggering assessments were carried out for the Darfield and Christchurch earthquakes, and compared against observed liquefaction surface manifestations and ground motions characteristics at each SMS. In general, the characteristics of the recorded ground motions at each site correlate well with the triggering analyses. However, at sites that likely liquefied at depth (as indicated by triggering analyses and/or inferred from the characteristics of the recorded surface acceleration time series), the presence of a non‐liquefiable crust layer at many of the SMS locations prevented the manifestation of any surface effects.

Research papers, University of Canterbury Library

Recurrent liquefaction in Christchurch during the 2010-2011 Canterbury earthquake sequence created a wealth of shallow subsurface intrusions with geometries and orientations governed by (1) strong ground motion severity and duration, and (2) intrinsic site characteristics including liquefaction susceptibility, lateral spreading severity, geomorphic setting, host sediment heterogeneity, and anthropogenic soil modifications. We present a suite of case studies that demonstrate how each of these characteristics influenced the geologic expressions of contemporary liquefaction in the shallow subsurface. We compare contemporary features with paleo-features to show how geologic investigations of recurrent liquefaction can provide novel insights into the shaking characteristics of modern and paleo-earthquakes, the influence of geomorphology on liquefaction vulnerability, and the possible controls of anthropogenic activity on the geologic record. We conclude that (a) sites of paleo-liquefaction in the last 1000-2000 years corresponded with most severe liquefaction during the Canterbury earthquake sequence, (b) less vulnerable sites that only liquefied in the strongest and most proximal contemporary earthquakes are unlikely to have liquefied in the last 1000-2000 years or more, (c) proximal strong earthquakes with large vertical accelerations favoured sill formation at some locations, (d) contemporary liquefaction was more severe than paleoliquefaction at all study sites, and (e) stratigraphic records of successive dike formation were more complete at sites with severe lateral spreading, (f) anthropogenic fill suppressed surface liquefaction features and altered subsurface liquefaction architecture.

Research papers, University of Canterbury Library

This presentation summarizes the development of high-resolution surficial soil velocity models in the Canterbury, New Zealand basin. Shallow (<30m) shear wave velocities were primarily computed based on a combination of a large database of over 15,000 cone penetration test (CPT) logs in and around Christchurch, and a recently-developed Christchurch-specific empirical correlation between soil shear wave velocity and CPT. Large active-source testing at 22 locations and ambient-wavefield surface wave and H/V testing at over 80 locations were utilized in combination with 1700 water well logs to constrain the inter-bedded stratigraphy and velocity of Quaternary sediments up to depths of several hundred meters. Finally, seismic reflection profiles and the ambient-wavefield surface wave data provide constraint on velocities from several hundred meters to several kilometres. At all depths, the high resolution data illustrates the complexity of the soil conditions in the region, and the developed 3D models are presently being used in broadband ground motion simulations to further interpret the observed strong ground motions in the 2010-2011 Canterbury earthquake sequence.

Research papers, University of Canterbury Library

The timeliness and quality of recovery activities are impacted by the organisation and human resourcing of the physical works. This research addresses the suitability of different resourcing strategies on post-disaster demolition and debris management programmes. This qualitative analysis primarily draws on five international case studies including 2010 Canterbury earthquake, 2009 L’Aquila earthquake, 2009 Samoan Tsunami, 2009 Victorian Bushfires and 2005 Hurricane Katrina. The implementation strategies are divided into two categories: collectively and individually facilitated works. The impacts of the implementation strategies chosen are assessed for all disaster waste management activities including demolition, waste collection, transportation, treatment and waste disposal. The impacts assessed include: timeliness, completeness of projects; and environmental, economic and social impacts. Generally, the case studies demonstrate that detritus waste removal and debris from major repair work is managed at an individual property level. Debris collection, demolition and disposal are generally and most effectively carried out as a collective activity. However, implementation strategies are affected by contextual factors (such as funding and legal constraints) and the nature of the disaster waste (degree of hazardous waste, geographical spread of waste etc.) and need to be designed accordingly. Community involvement in recovery activities such as demolition and debris removal is shown to contribute positively to psychosocial recovery.

Audio, Radio New Zealand

Post analysis of last night's All Black victory over the Wallabies and a look at the challenges ahead against Les Bleus; various looks at the Rena including mitigation of environmental impact and a 'please explain' summons to the lessees by the Transport Minister and; the Canterbury earthquake's Royal Commission hearings begin.

Research papers, University of Canterbury Library

Ongoing climate change triggers increasing temperature and more frequent extreme events which could limit optimal performance of haliotids, affect their physiology and biochemistry as well as influencing their population structure. Haliotids are a valuable nearshore fishery in a number of countries and many are showing a collapse of stocks because of overexploitation, environmental changes, loss of habitat, and disease. The haliotid in New Zealand commonly referred to as the blackfoot pāua (Haliotis iris) contribute a large and critical cultural, recreational and economic resource. Little was known about pāua responses to increasing temperature and acute environmental factors, as well as information about population size structure in Kaikoura after the earthquake 2016 and in Banks Peninsula. The aims of this study were to investigate the effects of temperature on scope for growth (SfG); physiological and biochemical responses of pāua subjected to different combined stressors including acute temperature, acute salinity and progressive hypoxia; and describe population size structure and shell morphology in different environments in Kaikoura and Banks Peninsula. The main findings of the present study found that population size structures of pāua were site-specific, and the shell length and shell height ratio of 3.25 could distinguish between stunted and non-stunted populations. The study found that high water temperature resulted in a reduction in absorbed energy from food, an increase in respiration energy, and ammonia excretion energy. Surveys were conducted at six study sites around the Canterbury Region over three years in order to better understand the population size structure and shell morphology of pāua. The findings found that the population size structure at 6 sites differed. Both juveniles and adults were found in intertidal areas at five sites. However, at Cape Three Points, pāua were found only in subtidal zones. One of the sites, Little Port Cooper, had a stunted population where only two pāua reached 125 mm in length over three years. In addition, most pāua in Little Port Cooper and Cape Three Points were adults, while Seal Reef had mostly juveniles. Wakatu Quay and Omihi had a full size range of pāua. Oaro population was dominated with juveniles and sub-adults. Recruitment and growth of pāua were successful after the earthquake in 2016. Research into pāua shell morphologies also determined that shell dimensions differed between sites. The relationships of shell length to shell width were linear and the relationship of shell length to shell height was curvilinear. Interestingly, SL:SH ratio of 3.25 is able to be used to identify stunted and non-stunted populations for pāua larger than 90 mm in length. Little Port Cooper was a stunted population with mean SL:SH ratio being 3.16. In the laboratory, scope for growth of pāua was investigated at four different temperatures of 12oC, 15oC, 18oC and 21oC over four weeks’ acclimation. The current study has found that SfG of pāua highly depended on temperature. Absorbed energy and respiration energy accounted for the highest proportion of the SfG of pāua. The respiration energy of pāua accounted for approximately 36%, 40%, 49% and 69% of the absorbed energy at 12°C, 15°C, 18°C and 21°C, respectively. The pāua at all acclimation temperatures had a positive scope for growth. The study suggested that the SfG was highest at 15°C, while the value at 21°C was the lowest. However, SfG at 18°C and 21°C decreased after 14 days of acclimation. Because of maintaining almost unchanged oxygen consumption over four weeks’ acclimation, pāua showed their poor abilities to acclimate to an increase in temperature. Therefore, they may be more vulnerable in future warming scenarios. The physiological and biochemical responses of pāua toward different combined stressors included three experiments. In terms of the acute temperature experiment, pāua were acclimated at 12oC, 15oC, 18oC or 21oC for two weeks before stepwise exposure to four temperatures of 12oC, 15oC, 18oC and 21oC every 4 hours. The acute salinity change, pāua were acclimated at 12oC, 15oC or 18oC over two weeks. Pāua were then exposed to a stepwise decrease of salinity of 2‰ every two hours from 34 – 22‰. Regarding the declining oxygen level, pāua were acclimated at 15 oC or 18oC for two weeks before exposure to one of four temperatures at 12oC, 15oC, 18oC or 21oC in one hour. After that acute progressive hypoxia was studied in closed respirometers for around six hours. The findings showed that there were interactions between combined stressors, affecting physiology of pāua (metabolism and heart rate). This suggests that environmental factors do not have a separate effect, but they also have interactions that enhance negative effects on pāua. Also, both oxygen uptake and heart rate responded quickly to temperature change and increased with rising temperature. On the other hand, oxygen uptake and heart rate decreased with reducing salinity and progressive hypoxia (before critical oxygen tension - Pcrit). Pcrit over four acute temperature exposures, ranged between 30.2 and 80.0 mmHg, depending on the exposure temperature. Acclimation temperature, combined with acute temperature, salinity or hypoxia stress affected the biochemistry of pāua. Pāua are osmoconformers so decreased salinity resulted in reducing haemolymph ionic concentration and increasing body volume. They were hypo-ionic with respect to sodium and potassium over the salinity ranges of 34 - 22‰. Haemocyanin accounts for a large pecentage of haemolymph protein, so trends of protein followed haemocyanin. Pāua tended to store oxygen in haemocyanin under extreme salinity stress at 22‰ and extreme hypoxia around 10 mmHg, rather than in oxygen transport. In conclusion, pāua at different sites had different population structures and morphologies. Pāua are sensitive to environmental stressors. They consumed more oxygen at high temperatures because they do not have thermal acclimation capacity. They are also osmoconformers with haemolymph sodium and potassium decreasing with salinity medium. Under progressive hypoxia, pāua could regulate oxygen and heart rate until Pcrit depending on temperature. Acute environmental changes also disturbed haemolyph parameters. 12°C and 15°C could be in the range of optimal temperature with higher SfG and less stress when exposed to acute environmental changes. Meanwhile long term exposure to 21°C is likely to be outside of the optimal range for the pāua. With ongoing climate change, pāua populations are more vulnerable so conservation is necessary. The research contributes to improving fishery management, providing insights into different environmental stressors affecting the energy demand and physiological and biochemical responses of pāua. It also allow to predicting the growth patterns and responses of pāua to adapt to climate change.

Research papers, University of Canterbury Library

Access to clean and safe drinking water is a fundamental human requirement. However, in many areas of the world natural water sources have been impacted by a variety of biological and chemical contaminants. The ingestion of these contaminants may cause acute or chronic health problems. To prevent such illnesses, many technologies have been developed to treat, disinfect and supply safe drinking water quality. However, despite these advancements, water supply distribution systems can adversely affect the drinking water quality before it is delivered to consumers. The primary aim of this research was to investigate the effect that water distribution systems may have on household drinking water quality in Christchurch, New Zealand and Addis Ababa, Ethiopia. Water samples were collected from the source water and household taps in both cities. The samples were then tested for various physical, chemical and biological water quality parameters. The data collected was also used to determine if water samples complied with national drinking water quality standards in both countries. Independent samples t-test statistical analyses were also performed to determine if water quality measured in the samples collected from the source and household taps was significantly different. Water quality did not vary considerably between the source and tap water samples collected in Christchurch City. No bacteria were detected in any sample. However, the pH and total iron concentrations measured in source and tap water samples were found to be significantly different. The lower pH values measured in tap water samples suggests that corrosion may be taking place in the distribution system. No water samples transgressed the Drinking Water Standards for New Zealand (DWSNZ) MAVs. Monitoring data collected by the Christchurch City Council (CCC) was also used for comparison. A number of pH, turbidity and total iron concentration measurements collected by the CCC in 2011 were found to exceed the guideline values. This is likely due to structural damage to the source wells and pump-stations that occurred during the 2011 earthquake events. Overall, it was concluded that the distribution system does not adversely affect the quality of Christchurch City’s household drinking water. The water quality measured in samples collected from the source (LTP) and household taps in Addis Ababa was found to vary considerably. The water collected from the source complied with the Ethiopian (WHO) drinking water quality standards. However, tap water samples were often found to have degraded water quality for the physical and chemical parameters tested. This was especially the case after supply interruption and reinstatement events. Bacteria were also often detected in household tap water samples. The results from this study indicate that water supply disruptions may result in degraded water quality. This may be due to a drop in pipeline pressure and the intrusion of contaminants through the leaky and cross-connected pipes in the distribution network. This adversely affects the drinking water quality in Addis Ababa.

Images, eqnz.chch.2010

Demolition of the relatively new seven-storey Waters Edge Apartments in Ferrymead continues. CERES Environmental NZ are doing the job for CERA (Canterbury Earthquake Recovery Authority). Some will be pleased to see this block go as there was lot of resentment to it being built on the site of the old Ferrymead Tavern, Selected for Explore, #347...

Research Papers, Lincoln University

The University of Canterbury held its inaugural Earthquake Forum on the 2nd September 2011. It was an opportunity to hear the diversity of earthquake-related research currently being undertaken in Canterbury and a chance for researchers and those working on the recovery to identify further areas where the research can support the recovery effort.The morning consisted of presentations showcasing the breadth of research currently underway and the afternoon will create the opportunity for people to connect in a series of concurrent workshops on the land, buildings and people. Neil Challenger's presentation covers landscape architecture, temporary landscapes, exploration of design ideas and specific student research related to urban design and earthquake recovery.