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Research papers, University of Canterbury Library

In this paper we apply Full waveform tomography (FWT) based on the Adjoint-Wavefield (AW) method to iteratively invert a 3-D geophysical velocity model for the Canterbury region (Lee, 2017) from a simple initial model. The seismic wavefields was generated using numerical solution of the 3-D elastodynamic/ visco- elastodynamic equations (EMOD3D was adopted (Graves, 1996)), and through the AW method, gradients of model parameters (compression and shear wave velocity) were computed by implementing the cross-adjoint of forward and backward wavefields. The reversed-in-time displacement residual was utilized as the adjoint source. For inversion, we also account for the near source/ station effects, gradient precondition, smoothening (Gaussian filter in spatial domain) and optimal step length. Simulation-to-observation misfit measurements based on 191 sources at 78 seismic stations in the Canterbury region (Figure 1) were used into our inversion. The inversion process includes multiple frequency bands, starting from 0-0.05Hz, and advancing to higher frequency bands (0-0.1Hz and 0-0.2Hz). Each frequency band was used for up to 10 iterations or no optimal step length found. After 3 FWT inversion runs, the simulated seismograms computed using our final model show a good matching with the observed seismograms at frequencies from 0 - 0.2 Hz and the normalized least-squared misfit error has been significantly reduced. Over all, the synthetic study of FWT shows a good application to improve the crustal velocity models from the existed geological models and the seismic data of the different earthquake events happened in the Canterbury region.

Images, UC QuakeStudies

One of the tents set up in the Fine Arts car park at the University of Canterbury, used for teaching while lecture theatres were closed for structural testing. The photographer comments, "Temporary lecture tents".

Images, eqnz.chch.2010

Photos taken in Lyttelton following the February 22 earthquake. Permit authorised by commanding officer HMNZS Canterbury. File ref: CCL-2011-03-05-After-The-Earthquake-P1110452 From the collection of Christchurch City Libraries

Research papers, University of Canterbury Library

Abstract This study provides a simplified methodology for pre-event data collection to support a faster and more accurate seismic loss estimation. Existing pre-event data collection frameworks are reviewed. Data gathered after the Canterbury earthquake sequences are analysed to evaluate the relative importance of different sources of building damage. Conclusions drawns are used to explore new approaches to conduct pre-event building assessment.

Research papers, University of Canterbury Library

Welcome to the Recover newsletter Issue 6 from the Marine Ecology Research Group (MERG) of the University of Canterbury. Recover is designed to keep you updated on our MBIE-funded earthquake recovery project called RECOVER (Reef Ecology, Coastal Values & Earthquake Recovery). This 6th instalment features the ‘new land’ created by the earthquake uplift of the coastline, recreational uses of beaches in Marlborough, and pāua survey work and hatchery projects with our partners in Kaikōura.

Images, UC QuakeStudies

A photograph of the earthquake-damaged Stone Chamber of the Canterbury Provincial Council Buildings on Durham Street North. Large sections of the Chamber have collapsed and the masonry and other rubble has spilled onto the footpath in front. To the left scaffolding constructed up the side of the building has also collapsed and twisted out of shape. Wire fences have been placed along the side of the building as a cordon.

Images, UC QuakeStudies

University of Canterbury ICT staff members prepare to be escorted to buildings by Civil Defence members in order to retrieve computers from offices. The photographer comments, "ICT staff head out to retrieve computers from buildings".

Images, UC QuakeStudies

University of Canterbury students walk along University Drive to get to lectures, after most pathways through campus were cordoned off while buildings were structurally tested. The photographer comments, "Lawns beside University Drive became main walkways".

Audio, UC QuakeStudies

An audio recording of a mayoral debate hosted by Generation Zero in partnership with 350 Christchurch. The event was titled Mayoral Debate: a climate-smart Christchurch. It was held on campus at the University of Canterbury on Thursday 22 September, 2016 and was moderated by Catarina Gutierrez of the Ministry of Awesome. The debate was structured as follows: Section 1: Candidates answered set questions sent prior to the event Section 2: Candidates answered set questions they have not seen before Interval Section 3: Candidates answered written questions from the audience (climate-related questions were submitted during the interval and a selection of these were given to the moderator). The audio recording was taken through the University's Echo system.

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.