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Research papers, University of Canterbury Library

Since the early 1980s seismic hazard assessment in New Zealand has been based on Probabilistic Seismic Hazard Analysis (PSHA). The most recent version of the New Zealand National Seismic Hazard Model, a PSHA model, was published by Stirling et al, in 2012. This model follows standard PSHA principals and combines a nation-wide model of active faults with a gridded point-source model based on the earthquake catalogue since 1840. These models are coupled with the ground-motion prediction equation of McVerry et al (2006). Additionally, we have developed a time-dependent clustering-based PSHA model for the Canterbury region (Gerstenberger et al, 2014) in response to the Canterbury earthquake sequence. We are now in the process of revising that national model. In this process we are investigating several of the fundamental assumptions in traditional PSHA and in how we modelled hazard in the past. For this project, we have three main focuses: 1) how do we design an optimal combination of multiple sources of information to produce the best forecast of earthquake rates in the next 50 years: can we improve upon a simple hybrid of fault sources and background sources, and can we better handle the uncertainties in the data and models (e.g., fault segmentation, frequency-magnitude distributions, time-dependence & clustering, low strain-rate areas, and subduction zone modelling)? 2) developing revised and new ground-motion predictions models including better capturing of epistemic uncertainty – a key focus in this work is developing a new strong ground motion catalogue for model development; and 3) how can we best quantify if changes we have made in our modelling are truly improvements? Throughout this process we are working toward incorporating numerical modelling results from physics based synthetic seismicity and ground-motion models.

Images, Canterbury Museum

Plastic and wood model of three liquefaction volcanoes. The working model pumps water over the grey surface which is decorated with a basket of laundry, a bucket of pegs and a football. The model is surrounded by artificial green grass and rests atop a black wooden base.

Research papers, University of Canterbury Library

Semi-empirical models based on in-situ geotechnical tests have become the standard of practice for predicting soil liquefaction. Since the inception of the “simplified” cyclic-stress model in 1971, variants based on various in-situ tests have been developed, including the Cone Penetration Test (CPT). More recently, prediction models based soley on remotely-sensed data were developed. Similar to systems that provide automated content on earthquake impacts, these “geospatial” models aim to predict liquefaction for rapid response and loss estimation using readily-available data. This data includes (i) common ground-motion intensity measures (e.g., PGA), which can either be provided in near-real-time following an earthquake, or predicted for a future event; and (ii) geospatial parameters derived from digital elevation models, which are used to infer characteristics of the subsurface relevent to liquefaction. However, the predictive capabilities of geospatial and geotechnical models have not been directly compared, which could elucidate techniques for improving the geospatial models, and which would provide a baseline for measuring improvements. Accordingly, this study assesses the realtive efficacy of liquefaction models based on geospatial vs. CPT data using 9,908 case-studies from the 2010-2016 Canterbury earthquakes. While the top-performing models are CPT-based, the geospatial models perform relatively well given their simplicity and low cost. Although further research is needed (e.g., to improve upon the performance of current models), the findings of this study suggest that geospatial models have the potential to provide valuable first-order predictions of liquefaction occurence and consequence. Towards this end, performance assessments of geospatial vs. geotechnical models are ongoing for more than 20 additional global earthquakes.

Images, Canterbury Museum

One oblong perspex covered 3-D model of the fault plains associated with the 4 September 2010 Darfield earthquake; top of the model also acts as a map overlay. Geologists continue to study the 4 September 2010 earthquake and consider it is likely to have been a complex event with several faults rupturing simultaneously. This model provides one ...

Images, Canterbury Museum

One model of the Temple for Christchurch with a rectangular base of Jarrah and solid silver conical shapes and wave like walls representing the movement of the 22 February 2011 earthquake. Based on the Temple for Christchurch sculpture that was designed by Hippathy Valentine.

Images, Canterbury Museum

One oblong perspex covered 3-D model of the fault plains that ruptured to cause the 22 February and 13 June 2011 earthquakes; top of the model also acts as a map overlay. This model provides a visual demonstration of the geological forces that caused the 22 February and 13 June 2011 earthquakes. These forces were so strong that parts of the Por...

Research papers, University of Canterbury Library

A team of earthquake geologists, seismologists and engineering seismologists from GNS Science, NIWA, University of Canterbury, and Victoria University of Wellington have collectively produced an update of the 2002 national probabilistic seismic hazard (PSH) model for New Zealand. The new model incorporates over 200 new onshore and offshore fault sources, and utilises newly developed New Zealand-based scaling relationships and methods for the parameterisation of the fault and subduction interface sources. The background seismicity model has also been updated to include new seismicity data, a new seismicity regionalisation, and improved methodology for calculation of the seismicity parameters. Background seismicity models allow for the occurrence of earthquakes away from the known fault sources, and are typically modelled as a grid of earthquake sources with rate parameters assigned from the historical seismicity catalogue. The Greendale Fault, which ruptured during the M7.1, 4 September 2010 Darfield earthquake, was unknown prior to the earthquake. However, the earthquake was to some extent accounted for in the PSH model. The maximum magnitude assumed in the background seismicity model for the area of the earthquake is 7.2 (larger than the Darfield event), but the location and geometry of the fault are not represented. Deaggregations of the PSH model for Christchurch at return periods of 500 years and above show that M7-7.5 fault and background source-derived earthquakes at distances less than 40 km are important contributors to the hazard. Therefore, earthquakes similar to the Darfield event feature prominently in the PSH model, even though the Greendale Fault was not an explicit model input.

Audio, Radio New Zealand

Christchurch artist Mike Beer creates miniature models of Christchurch buildings that were lost in the Canterbury earthquakes. Through these tiny models Mike hopes to remind people of the buildings that once shaped the city - and bring back the feelings and memories associated with them. Mike, who goes by the name Ghostcat, says It's all about the connections people have with a time, and place. His models are to be displayed at Fiksate Gallery in Christchuch from April 9.

Research papers, University of Canterbury Library

This research aims to explore how business models of SMEs revolve in the face of a crisis to be resilient. The business model canvas was used as a tool to analyse business models of SMEs in Greater Christchurch. The purpose was to evaluate the changes SMEs brought in their business models after hit by a series of earthquake in 2010 and 2011. The idea was to conduct interviews of business owners and analyse using grounded theory methods. Because this method is iterative, a tentative theoretical framework was proposed, half way through the data collection. It was realised that owner specific characteristics were more prominent in the data than the elements business model. Although, SMEs in this study experienced several operational changes in their business models such as change of location and modification of payment terms. However, the suggested framework highlights how owner specific attributes influence the survival of a small business. Small businesses and their owners are extremely interrelated that the business models personify the owner specific characteristics. In other words, the adaptation of the business model reflects the extent to which the owner possess these attributes. These attributes are (a) Mindsets – the attitude and optimism of business owner; (b) Adaptive coping – the ability of business owner to take corrective actions; and (c) Social capital – the network of a business owner, including family, friends, neighbours and business partners.

Research papers, University of Canterbury Library

The paper discusses modelling of cyclic stress-strain behaviour of soil, in particular a simple model that can produce a desired stiffness and hysteretic damping for a given strain level as observed in laboratory testing is formulated. The unloading-reloading relationship is developed for total stress seismic site response analysis with appropriate damping at large strain. The constitutive model employs a hyperbolic equation as the backbone curve, and uses a modification of the extended Masing unloading-reloading relationship leading to correct measured modulus reduction and damping curves simultaneously. A quasi-static cyclic loading of increasing amplitude is used to demonstrate the model’s performance and its capability to allow improved modelling of the magnitude of energy dissipation based on an experimental program on native sandy soils from Christchurch, New Zealand.

Research papers, University of Canterbury Library

A 3D high-resolution model of the geologic structure and associated seismic velocities in the Canterbury, New Zealand region is developed utilising data from depthconverted seismic reflection lines, petroleum and water well logs, cone penetration tests, and implicitly guided by existing contour maps and geologic cross sections in data sparse subregions. The model, developed using geostatistical Kriging, explicitly represents the significant and regionally recognisable geologic surfaces that mark the boundaries between geologic units with distinct lithology and age. The model is examined in the form of both geologic surface elevation contour maps as well as vertical cross sections of shear wave velocity, with the most prominent features being the Banks Peninsula Miocene-Pliocene volcanic edifice, and the Pegasus and Rakaia late Mesozoic-Neogene sedimentary basins. The adequacy of the modelled geologic surfaces is assessed through a residual analysis of point constraints used in the Kriging and qualitative comparisons with previous geologic models of subsets of the region. Seismic velocities for the lithological units between the geologic surfaces have also been derived, thus providing the necessary information for a Canterbury velocity model (CantVM) for use in physics-based seismic wave propagation. The developed model also has application for the determination of depths to specified shear wave velocities for use in empirical ground motion modelling, which is explicitly discussed via an example.

Images, UC QuakeStudies

A photograph of components of a model of the ChristChurch Cathedral being built from LEGO by Sam Butcher. Sam comments "Fixing a large variety of bits that were wrong/annoying/cheating (not purist) about the last model. The new one is set AFTER the Feb 22 earthquake. This newer, and much stronger model is also completely modular for easier transport. Obviously still a WIP, I'm currently waiting for a pretty large bricklink order at the moment, and will probably need to place a couple more after that too. Here you can see a couple of aspects of how the model is put together. The technique used proved - from what I tried - to be the best and strongest way to do it".

Images, UC QuakeStudies

A photograph of components of a model of the ChristChurch Cathedral being built from LEGO by Sam Butcher. Sam comments "Fixing a large variety of bits that were wrong/annoying/cheating (not purist) about the last model. The new one is set AFTER the Feb 22 earthquake. This newer, and much stronger model is also completely modular for easier transport. Obviously still a WIP, I'm currently waiting for a pretty large bricklink order at the moment, and will probably need to place a couple more after that too. Here you can see a couple of aspects of how the model is put together. The technique used proved - from what I tried - to be the best and strongest way to do it".

Images, UC QuakeStudies

A photograph of components of a model of the ChristChurch Cathedral being built from LEGO by Sam Butcher. Sam comments "Fixing a large variety of bits that were wrong/annoying/cheating (not purist) about the last model. The new one is set AFTER the Feb 22 earthquake. This newer, and much stronger model is also completely modular for easier transport. Obviously still a WIP, I'm currently waiting for a pretty large bricklink order at the moment, and will probably need to place a couple more after that too. Here you can see a couple of aspects of how the model is put together. The technique used proved - from what I tried - to be the best and strongest way to do it".

Images, UC QuakeStudies

A photograph of components of a model of the ChristChurch Cathedral being built from LEGO by Sam Butcher. Sam comments "Fixing a large variety of bits that were wrong/annoying/cheating (not purist) about the last model. The new one is set AFTER the Feb 22 earthquake. This newer, and much stronger model is also completely modular for easier transport. Obviously still a WIP, I'm currently waiting for a pretty large bricklink order at the moment, and will probably need to place a couple more after that to".