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Articles, Christchurch uncovered

It’s very easy to think of 19th century New Zealand as being a place isolated from the rest of the world. Yet as we research and investigate colonial Christchurch, we are constantly being reminded of the connections that existed between … Continue reading →

Articles, Christchurch uncovered

At the start of an archaeological investigation we often consult historical documents to learn as much as we can about a site’s past. Such research can identify the buildings that were once present, the people associated with the site through … Continue reading →

Articles, Christchurch uncovered

It’s that time of year again. Behold! Some of our favourite discoveries and images from 2015. It’s been an eventful twelve months. Archaeology happened. Sites were surveyed, excavated, photographed, investigated, disseminated and ruminated upon. Clues were followed and mysteries unrav...

Audio, Radio New Zealand

Toni Collins is a Canterbury University PhD researcher in law, who is investigating how commercial leases could be written to better deal with the aftermath of earthquakes, and how cases of disputes could progress through the courts.

Audio, Radio New Zealand

A lawyer who is suing Southern Response on behalf of earthquake claimants says he was intimidated by private investigators for another government agency in 2013. Southern Response is in charge of settling the outstanding quake claims of former AMI customers in Christchurch, but is now under investigation by the public sector watchdog, the State Services Commission. The Commission is looking at whether standards of integrity and conduct for state servants have been breached in its hiring of security company, Thompson and Clark. Southern Response says it hired the firm in 2014 to assess the level of risk some customers posed to staff. Lawyer Grant Shand tells Guyon Espiner he's waiting to see the results of the inquiry.

Audio, Radio New Zealand

The Prime Minister prepares for the Christchurch Call Summit in Paris saying governments need to protect their citizens from radicalisation, Police investigate who sent a threatening letter to the Earthquake Commission, A powerful 7.5 magnitude quake strikes PNG overnight.

Research papers, University of Canterbury Library

Earthquake events can be sudden, stressful, unpredictable, and uncontrollable events in which an individual’s internal and external assumptions of their environment may be disrupted. A number of studies have found depression, and other psychological symptoms may be common after natural disasters. They have also found an association between depression, losses and disruptions for survivors. The present study compared depression symptoms in two demographically matched communities differentially affected by the Canterbury (New Zealand) earthquakes. Hypotheses were informed by the theory of learned helplessness (Abramson, Seligman & Teasdale, 1978). A door-to-door survey was conducted in a more physically affected community sample (N=67) and a relatively unaffected community sample (N=67), 4 months after the February 2011 earthquake. Participants were again assessed approximately 10 months after the quake. Measures of depression, acute stress, anxiety, aftershock anxiety, losses, physical disruptions and psychological disruptions were taken. In addition, prior psychological symptoms, medication, alcohol and cigarette use were assessed. Participants in the more affected community reported higher depression scores than the less affected community. Overall, elevated depressive score at time 2 were predicted by depression at time 1, acute stress and anxiety symptoms at time 2, physical disruptions following the quake and psychosocial functioning disruptions at time 2. These results suggest the influence of acute stress, anxiety and disruptions in predicting depression sometime after an earthquake. Supportive interventions directed towards depression, and other psychological symptoms, may prove helpful in psychological adjustment following ongoing disruptive stressors and uncontrollable seismic activity.

Research papers, University of Canterbury Library

Geosynthetic reinforced soil (GRS) walls involve the use of geosynthetic reinforcement (polymer material) within the retained backfill, forming a reinforced soil block where transmission of overturning and sliding forces on the wall to the backfill occurs. Key advantages of GRS systems include the reduced need for large foundations, cost reduction (up to 50%), lower environmental costs, faster construction and significantly improved seismic performance as observed in previous earthquakes. Design methods in New Zealand have not been well established and as a result, GRS structures do not have a uniform level of seismic and static resistance; hence involve different risks of failure. Further research is required to better understand the seismic behaviour of GRS structures to advance design practices. The experimental study of this research involved a series of twelve 1-g shake table tests on reduced-scale (1:5) GRS wall models using the University of Canterbury shake-table. The seismic excitation of the models was unidirectional sinusoidal input motion with a predominant frequency of 5Hz and 10s duration. Seismic excitation of the model commenced at an acceleration amplitude level of 0.1g and was incrementally increased by 0.1g in subsequent excitation levels up to failure (excessive displacement of the wall panel). The wall models were 900mm high with a full-height rigid facing panel and five layers of Microgird reinforcement (reinforcement spacing of 150mm). The wall panel toe was founded on a rigid foundation and was free to slide. The backfill deposit was constructed from dry Albany sand to a backfill relative density, Dr = 85% or 50% through model vibration. The influence of GRS wall parameters such as reinforcement length and layout, backfill density and application of a 3kPa surcharge on the backfill surface was investigated in the testing sequence. Through extensive instrumentation of the wall models, the wall facing displacements, backfill accelerations, earth pressures and reinforcement loads were recorded at the varying levels of model excitation. Additionally, backfill deformation was also measured through high-speed imaging and Geotechnical Particle Image Velocimetry (GeoPIV) analysis. The GeoPIV analysis enabled the identification of the evolution of shear strains and volumetric strains within the backfill at low strain levels before failure of the wall thus allowing interpretations to be made regarding the strain development and shear band progression within the retained backfill. Rotation about the wall toe was the predominant failure mechanism in all excitation level with sliding only significant in the last two excitation levels, resulting in a bi-linear displacement acceleration curve. An increase in acceleration amplification with increasing excitation was observed with amplification factors of up to 1.5 recorded. Maximum seismic and static horizontal earth pressures were recorded at failure and were recorded at the wall toe. The highest reinforcement load was recorded at the lowest (deepest in the backfill) reinforcement layer with a decrease in peak load observed at failure, possibly due to pullout failure of the reinforcement layer. Conversely, peak reinforcement load was recorded at failure for the top reinforcement layer. The staggered reinforcement models exhibited greater wall stability than the uniform reinforcement models of L/H=0.75. However, similar critical accelerations were determined for the two wall models due to the coarseness of excitation level increments of 0.1g. The extended top reinforcements were found to restrict the rotational component of displacement and prevented the development of a preliminary shear band at the middle reinforcement layer, contributing positively to wall stability. Lower acceleration amplification factors were determined for the longer uniform reinforcement length models due to reduced model deformation. A greater distribution of reinforcement load towards the top two extended reinforcement layers was also observed in the staggered wall models. An increase in model backfill density was observed to result in greater wall stability than an increase in uniform reinforcement length. Greater acceleration amplification was observed in looser backfill models due to their lower model stiffness. Due to greater confinement of the reinforcement layers, greater reinforcement loads were developed in higher density wall models with less wall movement required to engage the reinforcement layers and mobilise their resistance. The application of surcharge on the backfill was observed to initially increase the wall stability due to greater normal stresses within the backfill but at greater excitation levels, the surcharge contribution to wall destabilising inertial forces outweighs its contribution to wall stability. As a result, no clear influence of surcharge on the critical acceleration of the wall models was observed. Lower acceleration amplification factors were observed for the surcharged models as the surcharge acts as a damper during excitation. The application of the surcharge also increases the magnitude of reinforcement load developed due to greater confinement and increased wall destabilising forces. The rotation of the wall panel resulted in the progressive development of shears surface with depth that extended from the backfill surface to the ends of the reinforcement (edge of the reinforced soil block). The resultant failure plane would have extended from the backfill surface to the lowest reinforcement layer before developing at the toe of the wall, forming a two-wedge failure mechanism. This is confirmed by development of failure planes at the lowest reinforcement layer (deepest with the backfill) and at the wall toe observed at the critical acceleration level. Key observations of the effect of different wall parameters from the GeoPIV results are found to be in good agreement with conclusions developed from the other forms of instrumentation. Further research is required to achieve the goal of developing seismic guidelines for GRS walls in geotechnical structures in New Zealand. This includes developing and testing wall models with a different facing type (segmental or wrap-around facing), load cell instrumentation of all reinforcement layers, dynamic loading on the wall panel and the use of local soils as the backfill material. Lastly, the limitations of the experimental procedure and wall models should be understood.

Research papers, University of Canterbury Library

1. Background and Objectives This poster presents results from ground motion simulations of small-to-moderate magnitude (3.5≤Mw≤5.0) earthquake events in the Canterbury, New Zealand region using the Graves and Pitarka (2010,2015) methodology. Subsequent investigation of systematic ground motion effects highlights the prediction bias in the simulations which are also benchmarked against empirical ground motion models (e.g. Bradley (2013)). In this study, 144 earthquake ruptures, modelled as point sources, are considered with 1924 quality-assured ground motions recorded across 45 strong motion stations throughout the Canterbury region, as shown in Figure 1. The majority of sources are Mw≥4.0 and have centroid depth (CD) 10km or shallower. Earthquake source descriptions were obtained from the GeoNet New Zealand earthquake catalogue. The ground motion simulations were performed within a computational domain of 140km x 120km x 46km with a finite difference grid spacing of 0.1km. The low-frequency (LF) simulations utilize the 3D Canterbury Velocity Model while the high-frequency (HF) simulations utilize a generic regional 1D velocity model. In the LF simulations, a minimum shear wave velocity of 500m/s is enforced, yielding a maximum frequency of 1.0Hz.

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11

Images, UC QuakeStudies

Time Capsule from the Oxford Terrace Baptist Church investigated by left to right Rev Chris Chamberlain, Senior Minister OTBC. Mike Crudge, Minister OTBC Lynn Campbell, Paper Conservator Christchurch Art Gallery Jeff Palmer, archivist Jill Durney from the Macmillan Brown library. 15.7.11