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Audio, Radio New Zealand

Victorian Authorities are warning residents of significant aftershocks following on from the magnitude 5.8 earthquake which shook Melbourne around 9am yesterday, causing significant structural damage across the city. The University of Melbourne's Dr Mark Quigley is a professor of tectonics, who became a familiar voice and face through the Christchurch quakes. Our producer Matthew Theunissen asked him how yesterday's quake compared to those he experienced in Christchurch.

Research papers, The University of Auckland Library

This thesis presents the application of data science techniques, especially machine learning, for the development of seismic damage and loss prediction models for residential buildings. Current post-earthquake building damage evaluation forms are developed for a particular country in mind. The lack of consistency hinders the comparison of building damage between different regions. A new paper form has been developed to address the need for a global universal methodology for post-earthquake building damage assessment. The form was successfully trialled in the street ‘La Morena’ in Mexico City following the 2017 Puebla earthquake. Aside from developing a framework for better input data for performance based earthquake engineering, this project also extended current techniques to derive insights from post-earthquake observations. Machine learning (ML) was applied to seismic damage data of residential buildings in Mexico City following the 2017 Puebla earthquake and in Christchurch following the 2010-2011 Canterbury earthquake sequence (CES). The experience showcased that it is readily possible to develop empirical data only driven models that can successfully identify key damage drivers and hidden underlying correlations without prior engineering knowledge. With adequate maintenance, such models have the potential to be rapidly and easily updated to allow improved damage and loss prediction accuracy and greater ability for models to be generalised. For ML models developed for the key events of the CES, the model trained using data from the 22 February 2011 event generalised the best for loss prediction. This is thought to be because of the large number of instances available for this event and the relatively limited class imbalance between the categories of the target attribute. For the CES, ML highlighted the importance of peak ground acceleration (PGA), building age, building size, liquefaction occurrence, and soil conditions as main factors which affected the losses in residential buildings in Christchurch. ML also highlighted the influence of liquefaction on the buildings losses related to the 22 February 2011 event. Further to the ML model development, the application of post-hoc methodologies was shown to be an effective way to derive insights for ML algorithms that are not intrinsically interpretable. Overall, these provide a basis for the development of ‘greybox’ ML models.

Audio, Radio New Zealand

The Aromaunga Baxters Flowers nursery in Heathcote, Christchurch sits right above the point where the earthquake struck on 22 February 2011. The greenhouses on the steep slopes of the Port Hills, as well as a big old villa and other brick buildings were badly damaged. Ten years on co-owner John Baxter says the earthquake damage is still being repaired, but sales have been boosted by a lack of imported flowers due to Covid-19 restrictions.

Audio, Radio New Zealand

As Christchurch prepares to mark 10 years since its deadly earthquake, the impact of that day continues to be felt differently. The less affluent eastern suburbs, which bore the brunt of the damage, continue to lag behind the rest of the city in their recovery. The former dean of Christchurch and fellow east sider, Peter Beck, told Conan Young that while government agencies such as EQC often failed people in their hour of need, what did not fail was the willingness of people to help out their neighbours.

Research papers, University of Canterbury Library

Glazing systems are non-structural elements in a building that, more often than not, appear to be given little consideration in seismic design. Recent experimental work into glazing systems at the University of Canterbury, however, has shown that glazing systems can be very susceptible to serviceability damage, defined as loss of water-tightness. The focus of this paper is to highlight the difference in vulnerability of standard and seismic glazing systems and consider the implications of this for future repair costs and losses. The paper first describes the damage states chosen for glazing units according to the repair strategies required and expected repair costs. This includes three damage states: DS1: Water Leakage, DS2: Gasket Failure and DS3: Frame/Glass Failure. Implementing modern performance-based earthquake engineering, the paper proceeds to highlight a case study comparing costs and expected losses of a standard glazing unit and a seismic glazing unit installed on a case study building. It is shown that the use of seismic glazing units is generally beneficial over time, due to the early onset of serviceability damage in standard glazing units. Finally, the paper provides suggestions for designers aimed at reducing costs related to earthquake induced repairs of glazing.