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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.

Images, UC QuakeStudies

Damage to Lyttelton following the 22 February 2011 earthquake. Ground Culinary Centre on the corner of London and Canterbury Streets. The wall on the top storey has crumbled into the street, covering the footpath in bricks. Large cracks can be seen above the door, coming out from the corners of the window.

Images, UC QuakeStudies

A broken window at ground level has building rubble behind it, some of which has been pushed out through the broken glass. The photographer comments, "The alternate title is 'Under Pressure'. A bulldozer must have pushed earthquake debris up against the internal wall not realising there was a glass reinforced window at ground level".

Images, UC QuakeStudies

A photograph of the earthquake damage to the Christchurch Chinese Methodist Church on Papanui Road. The gable walls have crumbled, bricks spilling onto the ground. The tower has been removed and braced on the ground in front. Cordon fencing has been placed around the building. Parts of the fence have been decorated with hearts and the word 'love'.

Images, Canterbury Museum

One landscape colour digital photograph taken on 6 September 2010 showing liquefaction in Hagley Park. Liquefaction is the name of the process where water pushes sand and silt above ground. These puddles of sand and silt are left above ground. Liquefaction caused huge problems when it occurred in residential suburbs as was as likely to push thr...