Knowledge of past climate variability is essential for understanding present and future climate trends. This study used Halocarpus biformis (pink pine) ring-width chronologies to investigate palaeotemperature history in Westland, New Zealand. The ensuing reconstruction is among the longest palaeoseries produced for New Zealand to date. It is in good agreement with other tree-ring-based records, and with instrumental (both local and hemispheric) data.
Thirteen pink pine chronologies were developed. Ring-width measurements were detrended using the Regional Curve Standardisation method to retain as much low-frequency variance as possible. Crossdating revealed the existence of a strong common signal among trees. Inter-site comparison indicated that a common control mechanism affected tree growth not only within sites, but also across sites.
To determine whether climate was the main factor that controlled the growth of pink pine in Westland, correlation and response function analyses were employed. Temperature, precipitation and the Southern Oscillation Index were tested for their relationship with tree growth. Mean monthly temperature was identified as the primary growth-limiting factor. Chronologies were positively correlated with temperature over an extended period (5-17 months), and climate response modelling showed that temperature explained 11-60% variance in the tree-ring data. The highest and most stable correlations occurred between tree growth and summer (January-March) temperatures.
Tree-ring data from the six sites that contained the strongest temperature signal were combined, and the Westland Regional Chronology (WRC) was developed. The WRC was then used to reconstruct January-March temperatures back to A.D. 1480. The calibration model explained 43% of the variance in temperature, and all calibration and verification tests were passed at high levels of significance. The reconstruction showed that temperatures in Westland have been following a positive trend over the last 520 years. The coolest 25-year period was 1542-1566, while temperatures reached their maximum in 1966-1990. Spectral analysis of the Westland palaeotemperature record revealed cycles at periods of about 3, 5-6, 11, 14, 22, 45 and 125 years.
This study also confirmed that climate response is species-dependent. A separate exercise, which compared two species from the same site, demonstrated that while pink pine's growth was mainly influenced by summer temperatures, Libocedrus bidwillii was affected by conditions at the beginning of the growing season. However, the temperature signal in Westland's Libocedrus bidwillii was insufficient to produce a reliable reconstruction. It might be because the climate signal in this species was obscured by disturbances, as was shown in the final section of this project. Frequent growth releases and suppressions implied that Libocedrus bidwillii integrated both major (Alpine Fault earthquakes) and minor (windthrow) disturbances in its ring widths. Pink pine, on the other hand, was not sensitive to disturbance, and was therefore a better indicator of palaeotemperatures in Westland.
This research has strengthened the New Zealand network of chronology sites, and confirmed that pink pine has great dendroclimatic value. The last 520 years of temperature fluctuations were reconstructed with a high degree of fidelity - the model developed in this thesis is currently the most accurate estimate of a temperature-growth relationship in the country.
The Ballantynes' Department Store fire in November 1947 claimed 41 lives and left a lasting scar on Christchurch — the city’s biggest single disaster until the 2011 earthquake. The events of that spring day are explored in this short film which intersperses archive footage with a fictional account of workers and customers in the tailoring department as the dramas of everyday life are suddenly overwhelmed. It was directed by Aileen O’Sullivan, shot by Alun Bollinger and made with the NZ Drama School graduating class of 2002 (with music by Gareth Farr).
The Acheron rock avalanche is located in the Red Hill valley almost 80 km west of Christchurch and is one of 42 greywacke-derived rock avalanches identified in the central Southern Alps. It overlies the Holocene active Porters Pass Fault; a component of the Porters Pass-Amberley Fault Zone which extends from the Rakaia River to beyond the Waimakariri River. The Porters Pass Fault is a dextral strike-slip fault system viewed as a series of discontinuous fault scarps. The location of the fault trace beneath the deposit suggests it may represent a possible source of seismic shaking resulting in the formation of the Acheron rock avalanche. The rock mass composition of the rock avalanche source scar is Torlesse Supergroup greywacke consisting of massive sandstone and thinly bedded mudstone sequences dipping steeply north into the centre of the source basin. A stability analysis identified potential instability along shallow north dipping planar defects, and steep south dipping toppling failure planes. The interaction of the defects with bedding is considered to have formed conditions for potential instability most likely triggered by a seismic event. The dTositional area of the rock avalanche covers 7.2 x 105 m2 with an estimated volume of 9 x 10 m3 The mobilised rock mass volume was calculated at 7.5 x 106 m3• Run out of the debris from the top of the source scar to the distal limit reached 3500m, descending over a vertical fall of almost 700m with an estimated Fahrboschung of 0.2. The run out of the rock avalanche displayed moderate to high mobility, travelling at an estimated maximum velocity of 140-160 km/hour. The rapid emplacement of the deposit is confirmed by highly fragmented internal composition and burial of forest vegetation New radiocarbon ages from buried wood retrieved from the base of Acheron rock avalanche deposit represents an emplacement age closely post-dating (Wk 12094) 1152 ± 51 years B.P. This differs significantly from a previous radiocarbon age of (NZ547) 500 ± 69 years B.P. and modal lichenometry and weathering-rind thickness ages of approximately 460 ± 10 yrs and 490 ± 50 years B.P. The new age shows no resemblance to an earthquake event around 700- 500 years B.P. on the Porters Pass-Amberley Fault Zone. The DAN run out simulation using a friction model rheology successfully replicated the long run out and velocity of the Acheron rock avalanche using a frictron angle of 27° and high earth pressure coefficients of 5.5, 5.2, and 5.9. The elevated earth pressure coefficients represent dispersive pressures derived from dynamic fragmentation of the debris within the mobile rock avalanche, supporting the hypothesis of Davies and McSaveney (2002). The DAN model has potential applications for areas prone to large-scale instability in the elevated slopes and steep waterways of the Southern Alps. A paleoseismic investigation of a newly identified scarp of the Porters Pass Fault partially buried by the rock avalanche was conducted to identify any evidence of a coseismic relationship to the Acheron rock avalanche. This identified three-four fault traces striking at 078°, and a sag pond displaying a sequence of overbank deposits containing two buried soils representing an earthquake event horizon. A 40cm vertical offset of the ponded sediment and lower buried soil horizqn was recorded, which was dated to (Wk 13112 charcoal in palosol) 653 ± 54 years B.P. and (Wk 13034 palosol) 661 ± 34 years B.P. The evidence indicates a fault rupture occurred along the Porters Pass Fault, west of Porters Pass most likely extending to the Red Lakes terraces, post-dating 700 years B.P., resulting in 40cm of vertical displacement and an unknown component of dextral strike slip movement. This event post dates the event one (1000 ± 100 years B.P) at Porters Pass previously considered to represent the most recent rupture along the fault line. This points to a probable source for resetting of the modal weathering-rind thicknesses and lichen size populations in the Red Hill valley and possibly the Red Lakes terraces. These results suggest careful consideration must be given to the geomorphic and paleoseismic history of a specific site when applying surface dating techniques and furthermore the origin of dates used in literature and their useful range should be verified. An event at 700-500 years B.P did not trigger the Acheron rock avalanche as previously assumed supporting Howard's conclusions. The lack of similar aged rupture evidence in either of the Porters Pass and Coleridge trenches supports Howard's hypothesis of segmentation of the Porters Pass Fault; where rupture occurs along one fault segment but not along another. The new rock avalanche age closely post-dating 1200-1100 years B.P. resembles the poorly constrained event one rupture age of 1700-800 years B.P for the Porters Pass Fault and the tighter constrained Round Top event of 1010 ± 50 years B.P. on the Alpine Fault. Eight other rock avalanche deposits spread across the central Southern Alps also resemble the new ages however are unable to be assigned specific earthquake events due to the large associated error bars of± 270 years. This clustering of ages does represent compelling lines of evidence for large magnitude earthquake events occurring over the central Southern Alps. The presence of a rock avalanche deposit does not signify an earthquake based on the historical evidence in the Southern Alps however clustering of ages does suggest that large Mw >7 earthquakes occurred across the Southern Alps between 1200-900 years BP.
This study contains an evaluation of the seismic hazard associated with the Springbank Fault, a blind structure discovered in 1998 close to Christchurch. The assessment of the seismic hazard is approached as a deterministic process in which it is necessary to establish: 1) fault characteristics; 2) the maximum earthquake that the fault is capable of producing and 3) ground motions estimations. Due to the blind nature of the fault, conventional techniques used to establish the basic fault characteristics for seismic hazard assessments could not be applied. Alternative methods are used including global positioning system (GPS) surveys, morphometric analyses along rivers, shallow seismic reflection surveys and computer modelling. These were supplemented by using multiple empirical equations relating fault attributes to earthquake magnitude, and attenuation relationships to estimate ground motions in the near-fault zone. The analyses indicated that the Springbank Fault is a reverse structure located approximately 30 km to the northwest of Christchurch, along a strike length of approximately 16 km between the Eyre and Ashley River. The fault does not reach the surface, buy it is associated with a broad anticline whose maximum topographic expression offers close to the mid-length of the fault. Two other reverse faults, the Eyrewell and Sefton Faults, are inferred in the study area. These faults, together with the Springbank and Hororata Faults and interpreted as part of a sys of trust/reverse faults propagating from a decollement located at mid-crustal depths of approximately 14 km beneath the Canterbury Plains Within this fault system, the Springbank Fault is considered to behave in a seismically independent way, with a fault slip rate of ~0.2 mm/yr, and the capacity of producing a reverse-slip earthquake of moment magnitude ~6.4, with an earthquake recurrence of 3,000 years. An earthquake of the above characteristics represents a significant seismic hazard for various urban centres in the near-fault zone including Christchurch, Rangiora, Oxford, Amberley, Kaiapoi, Darfield, Rollestion and Cust. Estimated peak ground accelerations for these towns range between 0.14 g to 0.5 g.
Environmental assessment in New Zealand is governed by the provisions of the Resource Management Act (RMA) 1991. The Act requires persons wishing to undertake certain activities to apply for resource consent from their local or regional council - a procedure termed the Resource Consent Process. The key component of a resource consent application is an Assessment of Environmental Effects (AEE) report; a statement of the environmental effects of a proposed activity.
Problems arise when environmental assessments are complicated by uncertain and abnormal circumstances such as natural hazards. Natural hazards (including earthquakes, floods, tsunami, and coastal erosion) can be catastrophic to an environment. If hazards are not avoided or successfully mitigated, they can result in serious consequences to proposed development and to the environment which the proposal relates. The aim of this study is to assess the adequacy of the resource consent process (as outlined in the Resource Management Act 1991) for dealing with proposed development affected by natural hazards.
This study reviews the context of the resource consent process for dealing with natural hazards to identify potential issues in the assessment process. Guidance criteria for assessing natural hazards (termed Natural Hazard Assessment) are developed to evaluate against two resource consent applications affected by natural hazards. The findings of the consent process review and case study evaluation are discussed to determine the adequacy of the consent process for dealing with natural hazards.
From the review of the consent process it was evident that the process has a number of problems for accommodating natural hazards into the assessment. Although many important traits are provided for in the process, such traits are not always reflected in environmental assessments.
Evaluation of two resource consent applications against the process of Natural Hazard Assessment (NHA) showed that these consent applications did not adequately detail key information relating to natural hazards. Many problems evident in these applications were not amended by the Consent Authorities in the review process and subsequently consent was granted to information-deficient applications. Problematic issues identified in this study include:
• A distinct lack of guidance (legal or otherwise) for the applicant and Consent Authority regarding the boundaries of inclusion of an effect;
• Deficiencies in planning documents are reflected in AEE reports, the review of the consent application and in the end-decision;
• Under-utilisation of "experts" throughout the consent process;
• Minimal identification and account for the degree of uncertainty throughout the consent process;
• Resource consents are being granted even though information in consent applications, and the means for assessing the information is deficient.
These issues reflect that decisions are not being made based on all elements involved in a potential hazard. Subsequently, the resource consent process is not adequate for dealing with all aspects of natural hazards.
The Natural Hazard Assessment process provides educated assessment criteria to assess development affected by natural hazards. By accounting for the problems evident in the consent process, the introduction of a three-tier identification, risk and vulnerability assessment, and evaluation process to account for uncertainties, Natural Hazard Assessment provides a platform for a thorough assessment of natural hazards. The application of the principles of Natural Hazard Assessment to the consent applications affected by natural hazards showed that many key issues were not covered in the assessment under the consent process.
The nature of a natural event is that one may not occur in a given region over many lifetimes, however they will occur at some stage and planning and environmental assessment needs to provide for the associated hazards. Implementation of Natural Hazard Assessment is needed to help provide answers for the problems experienced in the resource consent process. Natural Hazard Assessment would allow decision-makers to make informed judgements on the situation at hand, leading to better planning and land-use options.
Change to current practice is needed, as following the current path of environmental assessment will be the hazard in the end.
Slender precast concrete wall panels are currently in vogue for the construction of tall single storey warehouse type buildings. Often their height to thickness ratio exceed the present New Zealand design code (NZS 3101) limitations of 30:1. Their real performance under earthquake attack is unknown. Therefore, this study seeks to assess the dynamic performance of slender precast concrete wall panels with different base connection details. Three base connections (two fixed base and one rocking) from two wall specimens with height to thickness ratios of 60:1 were tested under dynamic loading. The two fixed based walls had longitudinal steel volumes of 1.27% to 0.54% and were tested on the University of Canterbury shaking table to investigate their proneness to out-of-plane buckling. Based on an EUler-type theoretical formula derived as part of the study, an explanation is made as to why walls with high in-plane capacity are more prone to buckling. The theory was validated against the present and past experimental evidence. The rocking base connection designed and built in accordance with a damage avoidance philosophy was tested on the shaking table in a similar fashion to the fixed base specimens. Results show that in contrast with their fixed base counterparts, rocking walls can indeed fulfil a damage-free design objective while also remaining stable under strong earthquake ground shaking.
