A large crack in the road surface in Kaiapoi, surrounded by liquefaction.
Damage to the asphalt surface of a car park in Kaiapoi.
A damaged road surface filled in with gravel. In the background is a cemetery.
A photograph of the undulating surface of Main Road in Mt Pleasant.
A photograph of the undulating surface of Main Road in Mt Pleasant.
Liquefaction in a horse paddock. In the foreground cracks are visible in the road surface.
A photograph of the warped surface of a car park in Antigua Street.
Despite the relatively low seismicity, a large earthquake in the Waikato region is expected to have a high impact, when the fourth-largest regional population and economy and the high density critical infrastructure systems in this region are considered. Furthermore, Waikato has a deep soft sedimentary basin, which increases the regional seismic hazard due to trapping and amplification of seismic waves and generation of localized surface waves within the basin. This phenomenon is known as the “Basin Effect”, and has been attributed to the increased damage in several historic earthquakes, including the 2010-2011 Canterbury earthquakes. In order to quantitatively model the basin response and improve the understanding of regional seismic hazard, geophysical methods will be used to develop shear wave velocity profiles across the Waikato basin. Active surface wave methods involve the deployment of linear arrays of geophones to record the surface waves generated by a sledge hammer. Passive surface wave methods involve the deployment of two-dimensional seismometer arrays to record ambient vibrations. At each site, the planned testing includes one active test and two to four passive arrays. The obtained data are processed to develop dispersion curves, which describe surface wave propagation velocity as a function of frequency (or wavelength). Dispersion curves are then inverted using the Geopsy software package to develop a suite of shear wave velocity profiles. Currently, more than ten sites in Waikato are under consideration for this project. This poster presents the preliminary results from the two sites that have been tested. The shear wave velocity profiles from all sites will be used to produce a 3D velocity model for the Waikato basin, a part of QuakeCoRE flagship programme 1.
Peraki Street in Kaiapoi, near the railway level crossing. The road and footpath surfaces are cracked and buckled.
Peraki Street in Kaiapoi, near the railway level crossing. The road and footpath surfaces are cracked and buckled.
Peraki Street in Kaiapoi, near the railway level crossing. The road and footpath surfaces are cracked and buckled.
Workers repairing power lines on Settlers Crescent in Ferrymead. Liquefaction silt can be seen on the road surface.
A photograph of damaged road surface. The photograph is captioned by Paul Corliss, "River Road, Avonside".
Signs at the entrance to the Gap Filler Pallet Pavilion read "No heels. No smoking. No climbing. Uneven surface please take care".
Damage to the footpath on Hereford Street. Yellow zigzags have been spray painted on the round to warn people of the irregular surface.
A woman inspecting a crack in the footpath in Avonside. Cones on either side warn pedestrians and cyclists of the uneven surface.
A man walks across his cracked and liquefaction-covered lawn in Richmond. The photographer comments, "Andy Corbin checks liquefaction and surface water in his lawn".
Cars slow for road works on Lineside Road, outside Kaiapoi, near the intersection with Revells Road. A truck is dumping gravel to fill cracks in the road surface.
Children play on the netball court at Lyttelton Main primary school. The surface of the court has been warped by the earthquakes.
A woman inspecting a crack in the footpath in Avonside. Cones on either side warn pedestrians and cyclists of the uneven surface.
A view over the Avon River towards Oxford Terrace where the road is badly cracked and slumping towards the river. Road cones mark the uneven surface.
A view down Robson Avenue in Avonside showing damage to the road surface and the footpath that has resulted from the 4 September 2010 earthquake.
A view down Robson Avenue in Avonside showing damage to the road surface and the footpath that has resulted from the 4 September 2010 earthquake.
A road roller parked on the side of Banks Avenue. The street is under repair and has a gravel surface. The photographer comments, "Road works in Banks Avenue".
We present initial results from a set of three-dimensional (3D) deterministic earthquake ground motion simulations for the northern Canterbury plains, Christchurch and the Banks Peninsula region, which explicitly incorporate the effects of the surface topography. The simu-lations are done using Hercules, an octree-based finite-element parallel software for solving 3D seismic wave propagation problems in heterogeneous media under kinematic faulting. We describe the efforts undertaken to couple Hercules with the South Island Velocity Model (SIVM), which included changes to the SIVM code in order to allow for single repetitive que-ries and thus achieve a seamless finite-element meshing process within the end-to-end ap-proach adopted in Hercules. We present our selection of the region of interest, which corre-sponds to an area of about 120 km × 120 km, with the 3D model reaching a depth of 60 km. Initial simulation parameters are set for relatively high minimum shear wave velocity and a low maximum frequency, which we are progressively scaling up as computing resources permit. While the effects of topography are typically more important at higher frequencies and low seismic velocities, even at this initial stage of our efforts (with a maximum of 2 Hz and a mini-mum of 500 m/s), it is possible to observe the importance of the topography in the response of some key locations within our model. To highlight these effects we compare the results of the 3D topographic model with respect to those of a flat (squashed) 3D model. We draw rele-vant conclusions from the study of topographic effects during earthquakes for this region and describe our plans for future work.
A photograph captioned by BeckerFraserPhotos, "A view looking along Poplar Lane. Two weeks earlier the surface of the lane was clear".
Damage to River Road in Richmond. The road surface is badly cracked and slumped, and liquefaction silt covers part of the road. The photographer comments, "Lateral spreading cracks in River Rd".
A photograph captioned by BeckerFraserPhotos, "The road surface of the Colombo Street bridge over the River Avon, showing the effect of compression".
A rubbish truck collects rubbish from the red bins along Rocking Horse Road in Southshore. The uneven surface of the road can be seen, with water pooling in the foreground.
Cracking along the pavement at Halswell Primary School. The ground has risen and fallen in places leaving an uneven surface where the children usually play.