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Images, UC QuakeStudies

A photograph captioned by BeckerFraserPhotos, "The failed column near the south-east corner of the ground floor of the Hotel Grand Chancellor. This corner of the building slumped 700mm when this column and a nearby sheer wall failed. Scaffolding was erected all around it and then sprayed with concrete to stabilise the building".

Images, UC QuakeStudies

Crack repairs on the Rendezvous Hotel in Gloucester Street. Cracks have been injected with epoxy resin using syringes. The epoxy resin leaves a peak around each hole which will be ground down to a smooth surface. The wall will then be repainted. This process actually makes the wall stronger than it was originally.

Images, UC QuakeStudies

A photograph captioned by BeckerFraserPhotos, "The failed column near the south-east corner of the ground floor of the Hotel Grand Chancellor. This corner of the building slumped 700mm when this column and a nearby sheer wall failed. Scaffolding was erected all around it and then sprayed with concrete to stabilise the building".

Images, UC QuakeStudies

The southern side of the Christ Church Cathedral with boarded up windows and damage to the roof above both of the transepts. Damaged masonry has been piled on the ground in front and one of the spires has been removed and braced with steel in the foreground.

Images, UC QuakeStudies

A sewage pumping station on Avonside Drive near the intersection with Robson Avenue has been lifted out of the ground by liquefaction. The photographer comments, "A Sunday afternoon ride to New Brighton, then back via Aranui, Wainoni, Dallington, and Richmond. Not a cheerful experience. Pumping station. Another hydraulically-lifted sewage pumping station, this time on Avonside Drive".

Images, UC QuakeStudies

A photograph of stencilled words on a footpath on Peterborough Street. The words read, "On Peterborough Street the houses are wonky. The ground has been pulled out from underneath them. The trick worked and the houses stayed up, but they are wonky. If you lived in them you might become wonky too".

Research papers, University of Canterbury Library

Damage distribution maps from strong earthquakes and recorded data from field experiments have repeatedly shown that the ground surface topography and subsurface stratigraphy play a decisive role in shaping the ground motion characteristics at a site. Published theoretical studies qualitatively agree with observations from past seismic events and experiments; quantitatively, however, they systematically underestimate the absolute level of topographic amplification up to an order of magnitude or more in some cases. We have hypothesized in previous work that this discrepancy stems from idealizations of the geometry, material properties, and incident motion characteristics that most theoretical studies make. In this study, we perform numerical simulations of seismic wave propagation in heterogeneous media with arbitrary ground surface geometry, and compare results with high quality field recordings from a site with strong surface topography. Our goal is to explore whether high-fidelity simulations and realistic numerical models can – contrary to theoretical models – capture quantitatively the frequency and amplitude characteristics of topographic effects. For validation, we use field data from a linear array of nine portable seismometers that we deployed on Mount Pleasant and Heathcote Valley, Christchurch, New Zealand, and we compute empirical standard spectral ratios (SSR) and single-station horizontal-to-vertical spectral ratios (HVSR). The instruments recorded ambient vibrations and remote earthquakes for a period of two months (March-April 2017). We next perform two-dimensional wave propagation simulations using the explicit finite difference code FLAC. We construct our numerical model using a high-resolution (8m) Digital Elevation Map (DEM) available for the site, an estimated subsurface stratigraphy consistent with the geomorphology of the site, and soil properties estimated from in-situ and non-destructive tests. We subject the model to in-plane and out-of-plane incident motions that span a broadband frequency range (0.1-20Hz). Numerical and empirical spectral ratios from our blind prediction are found in very good quantitative agreement for stations on the slope of Mount Pleasant and on the surface of Heathcote Valley, across a wide range of frequencies that reveal the role of topography, soil amplification and basin edge focusing on the distribution of ground surface motion.

Research papers, University of Canterbury Library

essential systems upon which the well-being and functioning of societies depend. They deliver a service or a good to the population using a network, a combination of spatially-distributed links and nodes. As they are interconnected, network elements’ functionality is also interdependent. In case of a failure of one component, many others could be momentarily brought out-of-service. Further problems arise for buried infrastructure when it comes to buried infrastructure in earthquake and liquefaction-prone areas for the following reasons: • Technically more demanding inspections than those required for surface horizontal infrastructure • Infrastructure subject to both permanent ground displacement and transient ground deformation • Increase in network maintenance costs (i.e. deterioration due to ageing material and seismic hazard) These challenges suggest careful studies on network resilience will yield significant benefits. For these reasons, the potable water network of Christchurch city (Figure 1) has been selected for its well-characterized topology and its extensive repair dataset.

Images, UC QuakeStudies

Damage to the Visitors Centre in Kaiapoi, after the September 4th earthquake. The foundations have lifted at the back of the building, giving it a forward lean. Cables have been attached to the balcony over the walkway and braced to posts cemented into the ground. This is to stop the building from slumping further.

Images, UC QuakeStudies

Damage to the Visitors Centre in Kaiapoi, after the September 4th earthquake. The foundations have lifted at the back of the building, giving it a forward lean. Cables have been attached to the balcony over the walkway and braced to posts cemented into the ground. This is to stop the building from slumping further.

Images, UC QuakeStudies

The damaged Ozone Hotel on Marine Parade. Fallen bricks lie on the ground in front of the building, which is surrounded by security fencing. The photographer comments, "A bike ride to New Brighton and the beach 3 weeks after the Feb 22 quake. Roads were still very rough and under reconstruction. Some buildings are still standing. but don't look too healthy".

Images, UC QuakeStudies

A photograph submitted by Scott Thomas to the QuakeStories website. The description reads, "The two separate piles of dirt outside on the street from mine and the 5 other townhouses I share my driveway with. In the distance you can see rubble on the ground and if you look carefully you can make out the bumps where the energy released has warped the road. Taken 28 February 2011.".

Images, UC QuakeStudies

St John's Presbyterian Church on Winchester Street in Lyttelton. The ground around the church has been strewn with masonry from the church's walls and collapsed tower. The building's front door has been red-stickered and a sign that reads "No entry" is stuck to it. The spire of the collapsed tower has fallen in front of the church, which has been enclosed by a safety fence.

Images, UC QuakeStudies

A photograph looking north up an alleyway on Tuam Street. The alleyway leads to Sol Square. There is a road cone in the middle of the alleyway. The message 'keep out' has been spray-painted on the ground on each side of the cone. In the distance there are bricks from several earthquake-damaged buildings in the alleyway.

Images, UC QuakeStudies

A photograph captioned by BeckerFraserPhotos, "Pieces of iron fretwork from the entrance to the Warners Hotel carefully laid on the ground in front of the building. Thisshows the careful salvaging which has taken place during the demolistion of many heritage building in order to be able to re-use significant pieces later".

Images, UC QuakeStudies

A photograph of the earthquake damage to a house on Woodham Road. The bottom storey of the house has crumbled, bringing the top storey to the ground. A large pile of bricks and two bay windows now lie beneath the top storey. A red sticker on one of the bay windows indicates that the house is unsafe to enter.

Images, UC QuakeStudies

A photograph of the earthquake damage to the Provincial Hotel on the corner of Barbadoes and Cashel Streets. The second storey walls have crumbled, and the bricks have fallen onto the ground below. Scaffolding erected in front of the building is now on a lean. Wire fencing has been placed around the building as a cordon.

Images, UC QuakeStudies

A photograph of the earthquake-damaged Cathedral of the Blessed Sacrament on Barbadoes Street. Rubble from the collapsed tower is lying on the ground in front. A car has been crushed under this rubble. Wire fencing, shipping containers, and road cones have been placed around the building as a cordon.

Images, UC QuakeStudies

A photograph of the earthquake-damaged Cathedral of the Blessed Sacrament on Barbadoes Street. Rubble from the collapsed tower is lying on the ground in front. A car has been crushed under this rubble. Wire fencing, shipping containers, and road cones have been placed around the building as a cordon.

Images, UC QuakeStudies

A photograph of the earthquake-damaged Cathedral of the Blessed Sacrament on Barbadoes Street. Rubble from the collapsed tower is lying on the ground in front. A car has been crushed under this rubble. Wire fencing, shipping containers, and road cones have been placed around the building as a cordon.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team inside an office. In the foreground, the drawers of filing cabinets have opened. Files and posters litter the ground. The coverings over the lights have shaken loose, and one is hanging just behind the ERT member.

Images, eqnz.chch.2010

It would have been a glorious Spring day in Christchurch had it not been for the magnitude 7.1 earthquake at 4:30 am. All the water and silt you can see covering the street in this photo erupted from the ground following the earthquake.

Images, UC QuakeStudies

A photograph of a block of damaged shops on the corner of Gloucester Street and Woodham Road. The top of the façade has crumbled. The bricks have fallen to the ground and taken the awnings with them. Wire fencing has been placed around the buildings as a cordon. Signs on the fences indicated that the T Bakery and Red Chilli are open.

Images, UC QuakeStudies

A plaque on the ground in front of the 'Passing Time' sculpture on the corner of Madras Street and St Asaph Street. The 'Passing Time' sculpture was installed outside the CPIT Building for the 6th SCAPE (a contemporary public art programme in Christchurch) a few days prior to the 22 February 2011 earthquake. The work features twisting boxes depicting each year between 1906 (the founding of CPIT) and 2010 (the date of the sculpture's production).

Images, UC QuakeStudies

A car stuck in a large pothole on River Road. The wheels on the right hand side of the car have fallen into the hole, leaving the car grounded against the road surface. The photographer comments, "This car belonged to a postal delivery worker - the NZ Post bike rack is mounted on the towbar. The owner must have biked home. Later a tow truck arrived to extract the car from the hole that had opened under its front wheel".

Research papers, University of Canterbury Library

Geospatial liquefaction models aim to predict liquefaction using data that is free and readily-available. This data includes (i) common ground-motion intensity measures; and (ii) geospatial parameters (e.g., among many, distance to rivers, distance to coast, and Vs30 estimated from topography) which are used to infer characteristics of the subsurface without in-situ testing. Since their recent inception, such models have been used to predict geohazard impacts throughout New Zealand (e.g., in conjunction with regional ground-motion simulations). While past studies have demonstrated that geospatial liquefaction-models show great promise, the resolution and accuracy of the geospatial data underlying these models is notably poor. As an example, mapped rivers and coastlines often plot hundreds of meters from their actual locations. This stems from the fact that geospatial models aim to rapidly predict liquefaction anywhere in the world and thus utilize the lowest common denominator of available geospatial data, even though higher quality data is often available (e.g., in New Zealand). Accordingly, this study investigates whether the performance of geospatial models can be improved using higher-quality input data. This analysis is performed using (i) 15,101 liquefaction case studies compiled from the 2010-2016 Canterbury Earthquakes; and (ii) geospatial data readily available in New Zealand. In particular, we utilize alternative, higher-quality data to estimate: locations of rivers and streams; location of coastline; depth to ground water; Vs30; and PGV. Most notably, a region-specific Vs30 model improves performance (Figs. 3-4), while other data variants generally have little-to-no effect, even when the “standard” and “high-quality” values differ significantly (Fig. 2). This finding is consistent with the greater sensitivity of geospatial models to Vs30, relative to any other input (Fig. 5), and has implications for modeling in locales worldwide where high quality geospatial data is available.