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Images, UC QuakeStudies

HITLab NZ's Andreas Dunser and UC clinical psychologists Dr Janet Carter, Dr Eileen Britt and Associate Professor Martin Dorahy, who are creating an earthquake simulator at the University of Canterbury to investigate ways to help Cantabrians overcome post-traumatic stress disorders caused by ongoing seismic activity.

Images, UC QuakeStudies

HITLab NZ's Andreas Dunser and UC clinical psychologists Dr Janet Carter, Dr Eileen Britt and Associate Professor Martin Dorahy, who are creating an earthquake simulator at the University of Canterbury to investigate ways to help Cantabrians overcome post-traumatic stress disorders caused by ongoing seismic activity.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

Damaged rose window of the St John the Baptist Church at Latimer Square; aftermath of the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Videos, eqnz.chch.2010

At Greendale Faultline on Highfield Road in mid-Canterbury, where the magnitude 7.1 earthquake on 4 September 2010 originated.

Images, eqnz.chch.2010

Repairs being carried out on this restaurant (converted from a church) at the Hereford Street / Manchester Street intersection;aftermath of the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Heaving and subsidence on the faultline left scars where the magnitude 7.1 earthquake on Saturday 4 September 2010 originated.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

The latest (but temporary) tourist attraction in mid-Canterbury! This was the previously unknown faultline where the Saturday 4 September 2010 earthquake originated.

Videos, eqnz.chch.2010

At Greendale Faultline on Highfield Road in mid-Canterbury, where the magnitude 7.1 earthquake on 4 September 2010 originated.

Videos, eqnz.chch.2010

At Greendale Faultline on Highfield Road in mid-Canterbury, where the magnitude 7.1 earthquake on 4 September 2010 originated.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

Tension cracks at least 300 mm deep, on the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.

Images, eqnz.chch.2010

This beautiful building on Madras Street is red stickered and may be condemned if the structural damage it suffered in the magnitude 7,1 earthquake on Saturday 4 September 2010 cannot be repaired.

Images, eqnz.chch.2010

Toppled grain silos on the outskirts of Darfield near the epicentre of the magnitude 7,1 earthquake that struck on Saturday 4 September 2010.

Images, eqnz.chch.2010

This beautiful building on Madras Street is red stickered and may be condemned if the structural damage it suffered in the magnitude 7,1 earthquake on Saturday 4 September 2010 cannot be repaired.

Images, eqnz.chch.2010

On the way to Darfield to locate the faultline where the tectonic plates slipped, causing the magnitude 7.1 earthquake on Saturday 4 September 2010.

Images, eqnz.chch.2010

This beautiful building on Madras Street is red stickered and may be condemned if the structural damage it suffered in the magnitude 7,1 earthquake on Saturday 4 September 2010 cannot be repaired.

Research papers, The University of Auckland Library

The full scale, in-situ investigations of instrumented buildings present an excellent opportunity to observe their dynamic response in as-built environment, which includes all the real physical properties of a structure under study and its surroundings. The recorded responses can be used for better understanding of behavior of structures by extracting their dynamic characteristics. It is significantly valuable to examine the behavior of buildings under different excitation scenarios. The trends in dynamic characteristics, such as modal frequencies and damping ratios, thus developed can provide quantitative data for the variations in the behavior of buildings. Moreover, such studies provide invaluable information for the development and calibration of realistic models for the prediction of seismic response of structures in model updating and structural health monitoring studies. This thesis comprises two parts. The first part presents an evaluation of seismic responses of two instrumented three storey RC buildings under a selection of 50 earthquakes and behavioral changes after Ms=7.1 Darfield (2010) and Ms=6.3 Christchurch (2011) earthquakes for an instrumented eight story RC building. The dynamic characteristics of the instrumented buildings were identified using state-of-the-art N4SID system identification technique. Seismic response trends were developed for the three storey instrumented buildings in light of the identified frequencies and the peak response accelerations (PRA). Frequencies were observed to decrease with excitation level while no trends are discernible for the damping ratios. Soil-structure interaction (SSI) effects were also determined to ascertain their contribution in the seismic response. For the eight storey building, it was found through system identification that strong nonlinearities in the structural response occurred and manifested themselves in all identified natural frequencies of the building that exhibited a marked decrease during the strong motion duration compared to the pre-Darfield earthquakes. Evidence of foundation rocking was also found that led to a slight decrease in the identified modal frequencies. Permanent stiffness loss was also observed after the strong motion events. The second part constitutes developing and calibrating finite element model (FEM) of the instrumented three storey RC building with a shear core. A three dimensional FEM of the building is developed in stages to analyze the effect of structural, non-structural components (NSCs) and SSI on the building dynamics. Further to accurately replicate the response of the building following the response trends developed in the first part of the thesis, sensitivity based model updating technique was applied. The FEMs were calibrated by tuning the updating parameters which are stiffnesses of concrete, NSCs and soil. The updating parameters were found to generally follow decreasing trends with the excitation level. Finally, the updated FEM was used in time history analyses to assess the building seismic performance at the serviceability limit state shaking. Overall, this research will contribute towards better understanding and prediction of the behavior of structures subjected to ground motion.

Research papers, University of Canterbury Library

The 2010-2011 Canterbury earthquakes were recorded over a dense strong motion network in the near-source region, yielding significant observational evidence of seismic complexities, and a basis for interpretation of multi-disciplinary datasets and induced damage to the natural and built environment. This paper provides an overview of observed strong motions from these events and retrospective comparisons with both empirical and physics-based ground motion models. Both empirical and physics-based methods provide good predictions of observations at short vibration periods in an average sense. However, observed ground motion amplitudes at specific locations, such as Heathcote Valley, are seen to systematically depart from ‘average’ empirical predictions as a result of near surface stratigraphic and topographic features which are well modelled via sitespecific response analyses. Significant insight into the long period bias in empirical predictions is obtained from the use of hybrid broadband ground motion simulation. The comparison of both empirical and physics-based simulations against a set of 10 events in the sequence clearly illustrates the potential for simulations to improve ground motion and site response prediction, both at present, and further in the future.

Research papers, University of Canterbury Library

This research employs a deterministic seismic risk assessment methodology to assess the potential damage and loss at meshblock level in the Christchurch CBD and Mount Pleasant primarily due to building damage caused by earthquake ground shaking. Expected losses in terms of dollar value and casualties are calculated for two earthquake scenarios. Findings are based on: (1) data describing the earthquake ground shaking and microzonation effects; (2) an inventory of buildings by value, floor area, replacement value, occupancy and age; (3) damage ratios defining the performance of buildings as a function of earthquake intensity; (4) daytime and night-time population distribution data and (5) casualty functions defining casualty risk as a function of building damage. A GIS serves as a platform for collecting, storing and analyzing the original and the derived data. It also allows for easy display of input and output data, providing a critical functionality for communication of outcomes. The results of this study suggest that economic losses due to building damage in the Christchurch CBD and Mount Pleasant will possibly be in the order of $5.6 and $35.3 million in a magnitude 8.0 Alpine fault earthquake and a magnitude 7.0 Ashley fault earthquake respectively. Damage to non-residential buildings constitutes the vast majority of the economic loss. Casualty numbers are expected to be between 0 and 10.

Research Papers, Lincoln University

There is a critical strand of literature suggesting that there are no ‘natural’ disasters (Abramovitz, 2001; Anderson and Woodrow, 1998; Clarke, 2008; Hinchliffe, 2004). There are only those that leave us – the people - more or less shaken and disturbed. There may be some substance to this; for example, how many readers recall the 7.8 magnitude earthquake centred in Fiordland in July 2009? Because it was so far away from a major centre and very few people suffered any consequences, the number is likely to be far fewer than those who remember (all too vividly) the relatively smaller 7.1 magnitude Canterbury quake of September 4th 2010 and the more recent 6.3 magnitude February 22nd 2011 event. One implication of this construction of disasters is that seismic events, like those in Canterbury, are as much socio-political as they are geological. Yet, as this paper shows, the temptation in recovery is to tick boxes and rebuild rather than recover, and to focus on hard infrastructure rather than civic expertise and community involvement. In this paper I draw upon different models of community engagement and use Putnam’s (1995) notion of ‘social capital’ to frame the argument that ‘building bridges’ after a disaster is a complex blend of engineering, communication and collaboration. I then present the results of a qualitative research project undertaken after the September 4th earthquake. This research helps to illustrate the important connections between technical rebuilding, social capital, recovery processes and overall urban resilience.

Research papers, University of Canterbury Library

This poster presents work to date on ground motion simulation validation and inversion for the Canterbury, New Zealand region. Recent developments have focused on the collection of different earthquake sources and the verification of the SPECFEM3D software package in forward and inverse simulations. SPECFEM3D is an open source software package which simulates seismic wave propagation and performs adjoint tomography based upon the spectral-element method. Figure 2: Fence diagrams of shear wave velocities highlighting the salient features of the (a) 1D Canterbury velocity model, and (b) 3D Canterbury velocity model. Figure 5: Seismic sources and strong motion stations in the South Island of New Zealand, and corresponding ray paths of observed ground motions. Figure 3: Domain used for the 19th October 2010 Mw 4.8 case study event including the location of the seismic source and strong motion stations. By understanding the predictive and inversion capabilities of SPECFEM3D, the current 3D Canterbury Velocity Model can be iteratively improved to better predict the observed ground motions. This is achieved by minimizing the misfit between observed and simulated ground motions using the built-in optimization algorithm. Figure 1 shows the Canterbury Velocity Model domain considered including the locations of small-to-moderate Mw events [3-4.5], strong motion stations, and ray paths of observed ground motions. The area covered by the ray paths essentially indicates the area of the model which will be most affected by the waveform inversion. The seismic sources used in the ground motion simulations are centroid moment tensor solutions obtained from GeoNet. All earthquake ruptures are modelled as point sources with a Gaussian source time function. The minimum Mw limit is enforced to ensure good signal-to-noise ratio and well constrained source parameters. The maximum Mw limit is enforced to ensure the point source approximation is valid and to minimize off-fault nonlinear effects.

Research papers, The University of Auckland Library

This thesis presents an assessment of historic seismic performance of the New Zealand stopbank network from the 1968 Inangahua earthquake through to the 2016 Kaikōura earthquake. An overview of the types of stopbanks and the main aspects of the design and construction of earthen stopbanks was presented. Stopbanks are structures that are widely used on the banks of rivers and other water bodies to protect against the impact of flood events. Earthen stopbanks are found to be the most used for such protection measures. Different stopbank damage or failure modes that may occur due to flooding or earthquake excitation were assessed with a focus on past earthquakes internationally, and examples of these damage and failure modes were presented. Stopbank damage and assessment reports were collated from available reconnaissance literature to develop the first geospatial database of stopbank damage observed in past earthquakes in New Zealand. Damage was observed in four earthquakes over the past 50 years, with a number of earthquakes resulting in no stopbank damage. The damage database therefore focussed on the Edgecumbe, Darfield, Christchurch and Kaikōura earthquakes. Cracking of the crest and liquefaction-induced settlement were the most common forms of damage observed. To understand the seismic demand on the stopbank network in past earthquakes, geospatial analyses were undertaken to approximate the peak ground acceleration (PGA) across the stopbank network for ten large earthquakes that have occurred in New Zealand over the past 50 years. The relationship between the demand, represented by the peak ground acceleration (PGA) and damage is discussed and key trends identified. Comparison of the seismic demand and the distribution of damage suggested that the seismic performance of the New Zealand stopbank network has been generally good across all events considered. Although a significant length of the stopbank networks were exposed to high levels of shaking in past events, the overall damage length was a small percentage of this. The key aspect controlling performance was the performance of the underlying foundation soils and the effect of this on the stopbank structure and stability.