Search

found 15843 results

Images for B&B; more images...

Articles, UC QuakeStudies

This study updated the 1999 Earthquake hazard and risk assessment study Stage 1 Part B: Probabilistic seismic hazard assessment and Earthquake scenarios for the Canterbury region, and historic earthquakes in Christchurch report. It incorporated new fault data, a new distributed seismicity model and new methods for estimating Modified Mercalli intensities. See Object Overview for background and usage information.

Articles, UC QuakeStudies

The Canterbury earthquakes destroyed the Christchurch CBD and caused massive disruption to business across the region. There was an urgent need to support business survival and foster economic recovery. Recover Canterbury is a hub providing seamless support for businesses affected by the earthquakes, giving them easy access to government and commercial expertise in a one-stop shop.

Images, eqnz.chch.2010

Broken head-stones as a result of the magnitude 6.3 quake in Christchurch - 22 February 2011. HDR process to add the "feeling" I felt at seeing this sort of damage.

Research papers, The University of Auckland Library

Micro - electro - mechanical system (MEMS) based accelerometers are now frequently used in many different parts of our day - to - day lives. It is also increasingly being used for structural testing applications. Researchers have had res ervation of using these devices as they are relatively untested, but now with the wider adoption, it provides a much cheaper and more versatile tool for structural engineering researchers. A number of damaged buildings in the Christchurch Central Business District (CBD) were instrumented with a number of low - cost MEMS accelerometers after the major Christchurch earthquakes. The accelerometers captured extremely high quality building response data as the buildings experienced thousands of aftershocks. This d ata set was amongst one of only a handful of data set s available around the world which provides building response data subjected to real ground motion. Furthermore, due to technological advances, a much larger than usual number of accelerometers has been deployed making the data set one of the most comprehensive available. This data set is utilised to extract modal parameters of the buildings. This paper summarises the operating requirements and preference for using such accelerometers for experimental mod al analysis. The challenges for adapting MEMS based devices for successful modal parameters identification are also discussed.

Research papers, University of Canterbury Library

Using case studies from the 2010-2011 Canterbury, New Zealand earthquake sequence, this study assesses the accuracies of paleoliquefaction back-analysis methods and explores the challenges, techniques, and uncertainties associated with their application. While liquefaction-based back-analyses have been widely used to estimate the magnitudes of paleoearthquakes, their uncertain efficacies continue to significantly affect the computed seismic hazard in regions where they are relied upon. Accordingly, their performance is evaluated herein using liquefaction data from modern earthquakes with known magnitudes. It is shown that when the earthquake source location and mechanism are known, back-analysis methods are capable of accurately deriving seismic parameters from liquefaction evidence. However, because the source location and mechanism are often unknown in paleoseismic studies, and because accurate interpretation is shown to be more difficult in such cases, new analysis techniques are proposed herein. An objective parameter is proposed to geospatially assess the likelihood of any provisional source location, enabling an analyst to more accurately estimate the magnitude of a liquefaction-inducing paleoearthquake. This study demonstrates the application of back-analysis methods, provides insight into their potential accuracies, and provides a framework for performing paleoliquefaction analyses worldwide.

Research papers, University of Canterbury Library

This report examines and compares case studies of labour market policy responses in APEC economies to natural disasters. It first reviews the policies and practice within APEC economies and internationally in managing the labour market effects of natural disasters. By using comparative case studies, the report then compares recent disaster events in the Asia-Pacific region, including: - the June 2013 Southern Alberta floods in Canada; - the 2010 and 2011 Queensland floods in Australia; - the 2010 and 2011 Canterbury earthquakes in New Zealand; - the 2011 Great East Japan Earthquake and Tsunami in Japan; and - the 2008 Wenchuan earthquake in China.

Research papers, University of Canterbury Library

Active faults capable of generating highly damaging earthquakes may not cause surface rupture (i.e., blind faults) or cause surface ruptures that evade detection due to subsequent burial or erosion by surface processes. Fault populations and earthquake frequency-­‐magnitude distributions adhere to power laws, implying that faults too small to cause surface rupture but large enough to cause localized strong ground shaking densely populate continental crust. The rupture of blind, previously undetected faults beneath Christchurch, New Zealand in a suite of earthquakes in 2010 and 2011, including the fatal 22 February 2011 moment magnitude (Mw) 6.2 Christchurch earthquake and other large aftershocks, caused a variety of environmental impacts, including major rockfall, severe liquefaction, and differential surface uplift and subsidence. All of these effects occurred where geologic evidence for penultimate effects of the same nature existed. To what extent could the geologic record have been used to infer the presence of proximal, blind and / or unidentified faults near Christchurch? In this instance, we argue that phenomena induced by high intensity shaking, such as rock fragmentation and rockfall, revealed the presence of proximal active faults in the Christchurch area prior to the recent earthquake sequence. Development of robust earthquake shaking proxy datasets should become a higher scientific priority, particularly in populated regions.

Research papers, University of Canterbury Library

Deep shear wave velocity (Vs) profiles (>400 m) were developed at 14 sites throughout Christchurch, New Zealand using surface wave methods. This paper focuses on the inversion of surface wave data collected at one of these sites, Hagley Park. This site is located on the deep soils of the Canterbury Plains, which consist of alluvial gravels inter-bedded with estuarine and marine sands, silts, clays and peats. Consequently, significant velocity contrasts exist at the interface between geologic formations. In order to develop realistic velocity models in this complex geologic environment, a-priori geotechnical and geologic data were used to identify the boundaries between geologic formations. This information aided in developing the layering for the inversion parameters. Moreover, empirical reference Vs profiles based on material type and confining pressure were used to develop realistic Vs ranges for each layer. Both the a-priori layering information and the reference Vs curves proved to be instrumental in generating realistic velocity models that account for the complex inter-bedded geology in the Canterbury Plains.

Research papers, University of Canterbury Library

Data from the 2010-2011 Canterbury earthquake sequence (CES) provides an unprecedented opportunity to assess and advance the current state of practice for evaluating liquefaction triggering. Towards this end, select case histories from the CES are used herein to assess the predictive capabilities of three alternative CPT-based simplified liquefaction evaluation procedures: Robertson and Wride (1998); Moss et al. (2006); and Idriss and Boulanger (2008). Additionally, the Liquefaction Potential Index (LPI) framework for predicting the severity of surficial liquefaction manifestations is also used to assess the predictive capabilities of the liquefaction evaluation procedures. Although it is not without limitations, use of the LPI framework for this purpose circumvents the need for selecting “critical” layers and their representative properties for study sites, which inherently involves subjectivity and thus has been a point of contention among researchers. It was found that while all the assessed liquefaction triggering evaluation procedures performed well for the parameter ranges of the sites analyzed, the procedure proposed by Idriss and Boulanger (2008) yielded predictions that are more consistent with field observations than the other procedures. However, use of the Idriss and Boulanger (2008) procedure in conjunction with a Christchurch-specific correlation to estimate fines content showed a decreased performance relative to using a generic fines content correlation. As a result, the fines correction for the Idriss and Boulanger (2008) procedure needs further study.

Research papers, University of Canterbury Library

In practice, several competing liquefaction evaluation procedures (LEPs) are used to compute factors of safety against soil liquefaction, often for use within a liquefaction potential index (LPI) framework to assess liquefaction hazard. At present, the influence of the selected LEP on the accuracy of LPI hazard assessment is unknown, and the need for LEP-specific calibrations of the LPI hazard scale has never been thoroughly investigated. Therefore, the aim of this study is to assess the efficacy of three CPT-based LEPs from the literature, operating within the LPI framework, for predicting the severity of liquefaction manifestation. Utilising more than 7000 liquefaction case studies from the 2010–2011 Canterbury (NZ) earthquake sequence, this study found that: (a) the relationship between liquefaction manifestation severity and computed LPI values is LEP-specific; (b) using a calibrated, LEP-specific hazard scale, the performance of the LPI models is essentially equivalent; and (c) the existing LPI framework has inherent limitations, resulting in inconsistent severity predictions against field observations for certain soil profiles, regardless of which LEP is used. It is unlikely that revisions of the LEPs will completely resolve these erroneous assessments. Rather, a revised index which more adequately accounts for the mechanics of liquefaction manifestation is needed.

Research papers, University of Canterbury Library

Despite their good performance in terms of their design objectives, many modern code-prescriptive buildings built in Christchurch, New Zealand had to be razed after the 2010-2011 Canterbury earthquakes because repairs were deemed too costly due to widespread sacrificial damage. Clearly a more effective design paradigm is needed to create more resilient structures. Rocking, post-tensioned connections with supplemental energy dissipation can contribute to a damage avoidance designs (DAD). However, few have achieved all three key design objectives of damage-resistant rocking, inherent recentering ability, and repeatable, damage-free energy dissipation for all cycles, which together offer a response which is independent of loading history. Results of experimental tests are presented for a near full-scale rocking beam-column sub-assemblage. A matrix of test results is presented for the system under varying levels of posttensioning, with and without supplemental dampers. Importantly, this parametric study delineates each contribution to response. Practical limitations on posttensioning are identified: a minimum to ensure static structural re-centering, and a maximum to ensure deformability without threadbar yielding. Good agreement between a mechanistic model and experimental results over all parameters and inputs indicates the model is robust and accurate for design. The overall results indicate that it is possible to create a DAD connection where the non-linear force-deformation response is loading history independent and repeatable over numerous loading cycles, without damage, creating the opportunity for the design and implementation of highly resilient structures.

Research papers, University of Canterbury Library

This study uses 44 high quality liquefaction case histories taken from 22 locations affected by the 2010-2011 Canterbury earthquake sequence to evaluate four commonly used CPT-VS correlations (i.e., Robertson, 2009; Hegazy and Mayne, 2006; Andrus et al., 2007; McGann et al., 2015b). Co-located CPT soundings and VS profiles, developed from surface wave testing, were obtained at 22 locations and case histories were developed for the Mw 7.1, 4 September 2010 Darfield and Mw 6.2, 22 February 2011 Christchurch earthquakes. The CPT soundings are used to generate VS profiles using each of four CPT-VS correlations. These correlated VS profiles are used to estimate the factor of safety against liquefaction using the Kayen et al. (2013) VS-based simplified liquefaction evaluation procedure. An error index is used to quantify the predictive capabilities of these correlations in relation to the observations of liquefaction (or the lack thereof). Additionally, the error indices from the CPT-correlated VS profiles are compared to those obtained using: (1) the Kayen et al. (2013) procedure with surface wave-derived VS profiles, and (2) the Idriss and Boulanger (2008) CPT-based liquefaction evaluation procedure. Based on the error indices, the evaluation procedures based on direct measurements of either CPT or VS provided more accurate liquefaction triggering estimates than those obtained from any of the CPT-VS correlations. However, the performance of the CPT-VS correlations varied, with the Robertson (2009) and Hegazy and Mayne (2006) correlations performing relatively poorly for the Christchurch soils and the Andrus et al. (2007) and McGann et al. (2015b) correlations performing better. The McGann et al. (2015b) correlation had the lowest error indices of the CPT-VS correlations tested, however, none of the CPT-VS correlations provided accurate enough VS predictions to be used for the evaluation of liquefaction triggering using the VS-based liquefaction evaluation procedures.

Images, eqnz.chch.2010

With the land dropping about 1metre to 1.4metres after the earthquakes, a few roads besides the Avon and Heathcote Rivers are flooded with very high tides. Extra stop banks (on right) erected after the quakes have helped, but the road is now well below high water level. New Brighton Road, just short of New Brighton. The Pages Road bridge may b...

Research papers, University of Canterbury Library

Science education research shows that a traditional, stand-and-deliver lecture format is less effective than teaching strategies that are learner-centred and that promote active engagement. The Carl Wieman Science Education Initiative (CWSEI) has used this research to develop resources to improve learning in university science courses. We report on a successful adaptation and implementation of CWSEI in the New Zealand university context. This two-year project at Massey University and the University of Canterbury began by using perception and concept surveys before and after undergraduate science courses to measure students’ attitudes towards science as well as their knowledge. Using these data, and classroom observations of student engagement and corroborating focus groups, the research team worked with lecturers to create interventions to enhance student engagement and learning in those courses. Results show several positive changes related to these interventions and they suggest several recommendations for lecturers and course coordinators. The recommendations include:1. Make learning outcomes clear, both for the lecturer and the students; this helps to cull extraneous material and scaffold student learning. 2. Use interactive activities to improve engagement, develop deeper levels of thinking, and improve learning. 3. Intentionally foster “expert-like thinking” amongst students in the first few semesters of the degree programme. 4. Be flexible because one size does not fit all and contextual events are beyond anyone’s control.In addition to these recommendations, data collected at the Canterbury site during the 2010 and 2011 earthquakes reinforced the understanding that the most carefully designed teaching innovations are subject to contextual conditions beyond the control of academics.

Research papers, University of Canterbury Library

his poster presents the ongoing development of a 3D Canterbury seismic velocity model which will be used in physics-based hybrid broadband ground motion simulation of the 2010-2011 Canterbury earthquakes. Velocity models must sufficiently represent critical aspects of the crustal structure over multiple length scales which will influence the results of the simulations. As a result, numerous sources of data are utilized in order to provide adequate resolution where necessary. Figure 2: (a) Seismic reflection line showing P-wave velocities and significant geologic horizons (Barnes et al. 2011), and (b) Shear wave profiles at 10 locations (Stokoe et al. 2013). Figure 4: Cross sections of the current version of the Canterbury velocity model to depths of 10km as shown in Figure 1: (a) at a constant latitude value of -43.6˚, and (b) at a constant longitude value of 172.64˚. 3. Ground Surface and Geologic Horizon Models Figure 3: (a) Ground surface model derived from numerous available digital elevation models, and (b) Base of the Quaternary sediments derived from structural contours and seismic reflection line elevations. The Canterbury region has a unique and complex geology which likely has a significant impact on strong ground motions, in particular the deep and loose deposits of the Canterbury basin. The Canterbury basin has several implications on seismic wave phenomena such as long period ground motion amplification and wave guide effects. Using a realistic 3D seismic velocity model in physics-based ground motion simulation will implicitly account for such effects and the resultant simulated ground motions can be studied to gain a fundamental understanding of the salient ground motion phenomena which occurred during the Canterbury earthquakes, and the potential for repeat occurrences in the Canterbury region. Figure 1 shows the current model domain as a rectangular area between Lat=[-43.2˚,-44.0˚], and Lon=[171.5˚,173.0˚]. This essentially spans the area between the foot of the Southern Alps in the North West to Banks Peninsula in the East. Currently the model extends to a depth of 50km below sea level.

Research papers, University of Canterbury Library

Describes an extensive experimental program at the University of Canterbury, for the development of new structural systems and connections for multi-storey laminated veneer lumber (LVL) timber buildings in earthquake-prone areas. The proposed innovative ductile timber connections are conceptually similar to recent seismic solutions successfully developed for precast concrete multi- storey buildings. The paper gives an overview of the research program, and the results of quasi-static cyclic tests on frame subassemblies, including exterior beam-column joints and cantilever columns, as well as pseudo-dynamic tests on cantilever columns. The experimental results showed significant dissipation of hysteretic energy, good self-centering capacity and no appreciable damage of the structural elements, confirming the expected enhanced performance of the proposed structural systems.

Research papers, University of Canterbury Library

A three dimensional approximately half scale experimental subassemblage is currently being tested at the University of Canterbury to investigate the effect of precast-prestressed floor units, which do not span past the internal columns, on the seismic performance of reinforced concrete moment resisting frames. This paper reports the preliminary results from the test, with the focus on elongation within the plastic hinges and strength enhancement in the frames. The preliminary results have shown that elongation between the external and internal plastic hinges varies by more than two fold. With the addition of the prestressed floor units, the strength of the moment resisting frame used in the test was found to be 25% higher than the current code specified value. In other situations, particularly where there are more than 2 bays in a moment resisting frame, greater strength enhancement may be expected. Any underestimation of beam strength is undesirable as it may result in the development of nonductile failure modes in a major earthquake.

Research papers, The University of Auckland Library

In the aftermath of the 2010-2011 Canterbury earthquakes in New Zealand, the residual capacity and reparability of damaged reinforced concrete (RC) structures was an issue pertinent to building owners, insurers, and structural engineers. Three precast RC moment-resisting frame specimens were extracted during the demolition of the Clarendon Tower in Christchurch after sustaining earthquake damage. These specimens were subjected to quasi-static cyclic testing as part of a research program to determine the reparability of the building. It was concluded that the precast RC frames were able to be repaired and retrofitted to an enhanced strength capacity with no observed reduction in displacement capacity, although the frames with “shear-ductile” detailing exhibited less displacement ductility capacity and energy dissipation capacity than the more conventionally detailed RC frames. Furthermore, the cyclic test results from the earthquake-damaged RC frames were used to verify the predicted inelastic demands applied to the specimens during the 2010-2011 Canterbury earthquakes. https://www.concrete.org/publications/acistructuraljournal.aspx

Images, Alexander Turnbull Library

Christ Church Cathedral, Christchurch, with spire being rebuilt after the 1901 earthquake. Photographer unidentified. The nave, tower and spire of Christchurch Cathedral was completed in 1881. Work on completeing the rest of the building began in 1900. In 1902 the transcepts were finished and work started on the chancel and apse. An earthquake in 1901 cracked the upper part of the spire in two places. In this photograph which dates from late 1902/1903 (see scaffolding beyond the transcept indicating work on chancel) the upper part of the spire has been removed by Messrs Graham and Greig in preparation for replacing this section with a copper covered wooden structure. The Cathedral was completed in 1904. (Information from "Vision and Reality; Christchurch Cathedral in the Square," Colin Brown, Christchurch, 2000 and "A Dream of Spires," Ian Lochhead, Canterbury University Press, 1999, page 153.) Preparation for erecting the scaffolding was reported in the Christchurch Star 15 January 1902. The cross was replaced on the top of the new copper covered wooden section of the spire on 29 June 1903. Source of descriptive information - Notes on file print. Source of title - Title supplied by Library Quantity: 1 b&w original negative(s). Physical Description: Glass negative

Research papers, Victoria University of Wellington

<b>Construction and Demolition (C&D) waste contributes to over 50% of New Zealand’s overall waste. Materials such as timber, plasterboard, and concrete make up 81% of the C&D waste that goes into landfills each year. Alongside this, more than 235 heritage-listed buildings have been demolished in Christchurch since the 2011 earthquakes. This research portfolio aims to find a solution to decrease C&D waste produced by demolishing heritage buildings.</b> With the recent announcement of The Cathedral of the Blessed Sacrament’s demolition, this will be another building added to the list of lost heritage in Christchurch. This research portfolio aims to bridge the relationship between heritage and waste through the recycling and reuse of the demolished materials, exploring the idea that history and heritage are preserved through building material reuse. This research portfolio mainly focuses on reducing construction and demolition waste in New Zealand, using the design of a new Catholic Cathedral as a vessel. This thesis will challenge how the construction and design industry deals with the demolition of heritage buildings and their contribution to New Zealand’s waste. It aims to explore the idea of building material reuse not only to reduce waste but also to retain the history and heritage of the demolished building within the materials.

Research papers, Victoria University of Wellington

<b>Ōtautahi-Christchurch faces the future in an enviable position. Compared to other New Zealand cities Christchurch has lower housing costs, less congestion, and a brand-new central city emerging from the rubble of the 2011 earthquakes. ‘Room to Breathe: designing a framework for medium density housing (MDH) in Ōtautahi-Christchurch’ seeks to answer the timely question how can medium density housing assist Ōtautahi-Christchurch to respond to growth in a way that supports a well-functioning urban environment? Using research by design, the argument is made that MDH can be used to support a safe, accessible, and connected urban environment that fosters community, while retaining a level of privacy. This is achieved through designing a neighbourhood concept addressing 3 morphological scales- macro- the city; meso- the neighbourhood; and micro- the home and street. The scales are used to inform a design framework for MDH specific to Ōtautahi-Christchurch, presenting a typological concept that takes full advantage of the benefits higher density living has to offer.</b> Room to Breathe proposes repurposing underutilised areas surrounding existing mass transit infrastructure to provide a concentrated populous who do not solely rely on private vehicles for transport. By considering all morphological scales Room to Breathe provides one suggestion on how MDH could become accepted as part of a well-functioning urban environment.

Research papers, University of Canterbury Library

The Porters Pass fault (PPF) is a prominent element of the Porters Pass-Amberley Fault Zone (PPAFZ) which forms a broad zone of active earth deformation ca 100 km long, 60-90 km west and north of Christchurch. For a distance of ca 40 km the PPF is defined by a series of discontinuous Holocene active traces between the Rakaia and Waimakariri Rivers. The amount of slip/event and the timing of paleoearthquakes are crucial components needed to estimate the earthquake potential of a fault. Movement was assumed to be, coseismic and was quantified by measuring displaced geomorphic features using either tape measure or surveying equipment. Clustering of offset data suggests that four to five earthquakes occurred on the PPF during the Holocene and these range between ca 5-7 m/event. Timing information was obtained from four trenches excavated across the fault and an auger adjacent to the fault. Organic samples from these sites were radiocarbon dated and used in conjunction with data from previous studies to identify the occurrence of at least four earthquakes at 8500 ± 200, 5300 ± 700, 2500 ± 200 and 1000 ± 100 years B.P. Evidence suggests that an additional event is also possible at 6200 ± 500 years B.P. The ~1000, 5300 and 6200 years B.P. paleoearthquakes were previously unrecognised, while the 500 year event previously inferred from rock-avalanche data has been discarded. The present data set produces recurrence intervals of ~2000-2500 years for the Holocene. The identification of only one Holocene PPF rupture to the west of Red Lakes indicates the presence of a segment boundary that prevents the propagation of rupture beyond this point. This is consistent with displacement data and results in slip rates of 0.5-0.7 mm/yr and 2.5-3.4 mm/yr to the west and east of Red Lakes respectively. It is possible that the nearby extensional Red Hill Fault influences PPF rupture propagation. The combination of geometric, slip rate and timing data has enabled the magnitude of prehistoric earthquakes on the PPF to be estimated. These magnitudes range from an average of between 6.9 for a fault rupture from Waimakariri River to Red Lakes, to a maximum of 7.4 that ruptures the entire length of the PPAFZ, including the full length of the PPF. These estimates are approximately consistent with previous magnitude estimates along the full length of the PPAFZ of between 7.0 and 7.5.

Research papers, University of Canterbury Library

This paper describes part of an extensive experimental programme in progress at the University of Canterbury to develop Laminated Veneer Lumber (LVL) structural systems and connections for multistorey timber buildings in earthquake-prone areas. The higher mechanical properties of LVL, when compared to sawn timber, in addition to its low mass, flexibility of design and rapidity of construction, create the potential for increased use of LVL in multi-storey buildings. The development of these innovative ductile connections in LVL, proposed here for frame systems, have been based on the successful implementation of jointed ductile connections for precast concrete systems, started in the early 1990s with the PRESSS Program at the University of California, San Diego, further developed in Italy and currently under further refinement at the University of Canterbury. This paper investigates the seismic behaviour of the so-called “hybrid” connection, characterised by the combination of unbonded post-tensioned tendons and either external or internal energy dissipaters passing through the critical contact surface between the structural elements. Experimental results on hybrid exterior beam-to-column and column-to-foundation subassemblies under cyclic quasi-static unidirectional loading are presented. The proposed innovative solutions exhibit a very satisfactory seismic performance characterised by an appreciable energy dissipation capacity (provided by the dissipaters) combined with self-centring properties (provided by the unbonded tendons) and negligible damage of the LVL structural elements.

Research papers, University of Canterbury Library

Seismic behaviour of typical unreinforced masonry (URM) brick houses, that were common in early last century in New Zealand and still common in many developing countries, is experimentally investigated at University of Canterbury, New Zealand in this research. A one halfscale model URM house is constructed and tested under earthquake ground motions on a shaking table. The model structure with aspect ratio of 1.5:1 in plan was initially tested in the longitudinal direction for several earthquakes with peak ground acceleration (PGA) up to 0.5g. Toppling of end gables (above the eaves line) and minor to moderate cracking around window and door piers was observed in this phase. The structure was then rotated 90º and tested in the transverse (short) direction for ground motions with PGA up to 0.8g. Partial out-of-plane failure of the face loaded walls in the second storey and global rocking of the model was observed in this phase. A finite element analysis and a mechanism analysis are conducted to assess the dynamic properties and lateral strength of the model house. Seismic fragility function of URM houses is developed based on the experimental results. Damping at different phases of the response is estimated using an amplitude dependent equivalent viscous damping model. Financial risk of similar URM houses is then estimated in term of expected annual loss (EAL) following a probabilistic financial risk assessment framework. Risks posed by different levels of damage and by earthquakes of different frequencies are then examined.

Research papers, The University of Auckland Library

The region in and around Christchurch, encompassing Christchurch city and the Selwyn and Waimakariri districts, contains more than 800 road, rail, and pedestrian bridges. Most of these bridges are reinforced concrete, symmetric, and have small to moderate spans (15–25 m). The 22 February 2011 moment magnitude (Mw) 6.2 Christchurch earthquake induced high levels of localized ground shaking (Bradley and Cubrinovski 2011, page 853 of this issue; Guidotti et al. 2011, page 767 of this issue; Smyrou et al. 2011, page 882 of this issue), with damage to bridges mainly confined to the central and eastern parts of Christchurch. Liquefaction was evident over much of this part of the city, with lateral spreading affecting bridges spanning both the Avon and Heathcote rivers.

Images, eqnz.chch.2010

The two nice trees in the front of my old property (now owned by the government) have been cut down so the main section of the house behind could be trucked down the drive. The truck must have been up against the fence to get the height above the house to the left (15 Velsheda Street). Down this drive were numbers 17, 19 and 21 (still occupied b...

Research papers, University of Canterbury Library

The Lake Coleridge Rock Avalanche Deposits (LCRADs) are located on Ryton Station in the middle Rakaia Valley, approximately 80 km west of Christchurch. Torlesse Supergroup greywacke is the basement material and has been significantly influenced by both active tectonics and glaciation. Both glacial and post-glacial processes have produced large volumes of material which blanket the bedrock on slopes and in the valley floors. The LCRADs were part of a regional study of rock avalanches by WHITEHOUSE (1981, 1983) and WHITEHOUSE and GRIFFITHS (1983), and a single rock avalanche event was recognised with a weathering rind age of 120 years B.P. that was later modified to 150 ± 40 years B.P. The present study has refined details of both the age and the sequence of events at the site, by identifying three separate rock avalanche deposits (termed the LCRA1, LCRA2 and LCRA3 deposits), which are all sourced from near the summit of Carriage Drive. The LCRA1 deposit is lobate in shape and had an estimated original deposit volume of 12.5 x 10⁶ m³, although erosion by the Ryton River has reduced the present day debris volume to 5.1 x 10⁶ m³. An optically stimulated luminescence date taken from sandy loess immediately beneath the LCRA1 deposit provided a maximum age for the rock avalanche event of 9,720 ± 750 years B.P., which is believed to be realistic given that this is shortly after the retreat of Acheron 3 ice from this part of the valley. Emplacement of rock avalanche material into an ancestral Ryton riverbed created a natural dam with a ~17 M m³ lake upstream. The river is thought to have created a natural spillway over the dam structure at ~557 m (a.s.l), and to have existed for a number of years before any significant downcutting occurred. Although a triggering mechanism for the LCRA1 deposit was poorly constrained, it is thought that stress rebound after glacial ice removal may have initiated failure. Due to the event occurring c.10,000 years ago, there was a lack of definition for a possible earthquake trigger, though the possibility is obvious. The LCRA₂ event had an original deposit volume of 0.66 x 10⁶ m³, and was constrained to the low-lying area adjacent to the Ryton River that had been created by river erosion of the LCRA1 deposit. Further erosion by the Ryton River has reduced the deposit volume to 0.4 x 10⁶ m³. A radiocarbon date from a piece of mānuka found within the LCRA2 deposit provided an age of 668 ± 36 years B.P., and this is thought to reliably date the event. The LCRA2 event also dammed the Ryton River, and the preservation of dam-break outwash terraces downstream from the deposit provides clear evidence of rapid dam erosion and flooding after overtopping, and breaching by the Ryton River. Based on the mean annual flow of the Ryton River, the LCRA2 lake would have taken approximately two weeks to fill assuming that there were no preferred breach paths and the material was relatively impermeable. The LCRA2 event is thought to have been coseismic with a fault rupture along the western segment of the PPAFZ, which has been dated at 600 ± 100 years B.P. by SMITH (2003). The small LCRA3 event was not able to be dated, but it is believed to have failed shortly after the LCRA2 event and it may in fact be a lag deposit of the second rock avalanche event possibly triggered by an aftershock. The deposit is only visible at one locality within the cliffs that line the Ryton River, and its lack of geomorphic expression is attributed to it occurring closely after the LCRA2 event, while the Ryton River was still dammed from the second rock avalanche event. A wedge-block of some 35,000 m³ of source material for a future rock avalanche was identified at the summit of Carriage Drive. The dilation of the rock mass, combined with unfavourably oriented sub-vertical bedding in the Torlesse Supergroup bedrock, has allowed toppling-style failure on both of the main ridge lines around the source area for the LCRADs. In the event of a future rock avalanche occurring within the Ryton riverbed an emergency response plan has been developed to provide a staged response, especially in relation to the camping ground located at the mouth of the Ryton River. A long-term management plan has also been developed for mitigation measures for the Ryton riverbed and adjacent floodplain areas downstream of a future rock avalanche at the LCRAD site.