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Research papers, University of Canterbury Library

The 4 September 2010 Darfield and 22 February 2011 Christchurch earthquakes caused significant damage to Christchurch and surrounding suburbs as a result of the widespread liquefaction and lateral spreading that occurred. Ground surveying-based field investigations were conducted following these two events in order to measure permanent ground displacements in areas significantly affected by lateral spreading. Data was analysed with respect to the distribution of lateral spreading vs. distance from the waterway, and the failure patterns observed. Two types of failure distribution patterns were observed, a typical distributed pattern and an atypical block failure. Differences in lateral spreading measurements along adjacent banks of the Avon River in the area of Dallington were also examined. The spreading patterns between the adjacent banks varied with the respective river geometry and/or geotechnical conditions at the banks.

Research papers, University of Canterbury Library

In the period between September 2010 and December 2011, Christchurch was shaken by a series of strong earthquakes including the MW7.1 4 September 2010, Mw 6.2 22 February 2011, MW6.2 13 June 2011 and MW6.0 23 December 2011 earthquakes. These earthquakes produced very strong ground motions throughout the city and surrounding areas that resulted in soil liquefaction and lateral spreading causing substantial damage to buildings, infrastructure and the community. The stopbank network along the Kaiapoi and Avon River suffered extensive damage with repairs projected to take several years to complete. This presented an opportunity to undertake a case-study on a regional scale of the effects of liquefaction on a stopbank system. Ultimately, this information can be used to determine simple performance-based concepts that can be applied in practice to improve the resilience of river protection works. The research presented in this thesis draws from data collected following the 4th September 2010 and 22nd February 2011 earthquakes. The stopbank damage is categorised into seven key deformation modes that were interpreted from aerial photographs, consultant reports, damage photographs and site visits. Each deformation mode provides an assessment of the observed mechanism of failure behind liquefaction-induced stopbank damage and the factors that influence a particular style of deformation. The deformation modes have been used to create a severity classification for the whole stopbank system, being ‘no or low damage’ and ‘major or severe damage’, in order to discriminate the indicators and factors that contribute to ‘major to severe damage’ from the factors that contribute to all levels of damage a number of calculated, land damage, stopbank damage and geomorphological parameters were analysed and compared at 178 locations along the Kaiapoi and Avon River stopbank systems. A critical liquefiable layer was present at every location with relatively consistent geotechnical parameters (cone resistance (qc), soil behaviour type (Ic) and Factor of Safety (FoS)) across the study site. In 95% of the cases the critical layer occurred within two times the Height of the Free Face (HFF,). A statistical analysis of the geotechnical factors relating to the critical layer was undertaken in order to find correlations between specific deformation modes and geotechnical factors. It was found that each individual deformation mode involves a complex interplay of factors that are difficult to represent through correlative analysis. There was, however, sufficient data to derive the key factors that have affected the severity of deformation. It was concluded that stopbank damage is directly related to the presence of liquefaction in the ground materials beneath the stopbanks, but is not critical in determining the type or severity of damage, instead it is merely the triggering mechanism. Once liquefaction is triggered it is the gravity-induced deformation that causes the damage rather than the shaking duration. Lateral spreading and specifically the depositional setting was found to be the key aspect in determining the severity and type of deformation along the stopbank system. The presence or absence of abandoned or old river channels and point bar deposits was found to significantly influence the severity and type of deformation. A review of digital elevation models and old maps along the Kaiapoi River found that all of the ‘major to severe’ damage observed occurred within or directly adjacent to an abandoned river channel. Whilst a review of the geomorphology along the Avon River showed that every location within a point bar deposit suffered some form of damage, due to the depositional environment creating a deposit highly susceptible to liquefaction.

Videos, UC QuakeStudies

A video of a dug-out soil pit on a farm near River Road in Lincoln. There is a thick layer of saturated sand between the topsoil and the subsoil where the grass roots end. The saturated soil is collapsing as a result of contractor Tony Fisher, of Fisher Agriculture Ltd, having jumped lightly up and down on the edge of the pit.

Videos, UC QuakeStudies

A video of a dug-out soil pit on a farm near River Road in Lincoln. There is a thick layer of saturated sand between the topsoil and the subsoil where the grass roots end. The saturated soil is collapsing as a result of contractor Tony Fisher, of Fisher Agriculture Ltd, jumping lightly up and down on the edge of the pit.

Videos, UC QuakeStudies

A video of contractor Tony Fisher, of Fisher Agricultural Ltd, jumping lightly up and down on the edge of a dug-out soil pit on a farm near River Road in Lincoln. There is a thick layer of saturated sand between the topsoil and the subsoil where the grass roots end. The saturated soil starts to collapse as a result of the movement.

Images, UC QuakeStudies

Pallet Golf', a Gap Golf course on a the site of a demolished building. It has been built by Gap Filler to look like a journey through Christchurch. A plastic road cone as well as mini road cones, road signs, tunnels and rivers can be seen. The course has been built using green felt, wooden pallets, tyres, planks of wood and bricks.

Images, UC QuakeStudies

Photograph captioned by Fairfax, "Members of the Red Cross civil defence response team and South Canterbury Police have been in Christchurch helping with the earthquake clean up. Welfare checks required the team to walk along River Road checking on householders. Pictured from left are Aaron Sole, Andy Todd, Anna Munro, Ken Weavers, Tim Mitchell (Emergency Management Officer) and Tom Connolly".

Videos, UC QuakeStudies

A video of the removal of the earthquake-damaged Medway Street bridge from the banks of the Avon River. The video shows members of the Stronger Christchurch Infrastructure Rebuild Team removing the bridge and preparing it for transport to the Ferrymead Heritage Park. It will remain at the park until a permanent home can be found for it as an earthquake memorial.

Images, UC QuakeStudies

Damage to a house in Richmond. The brick wall is badly cracked and twisted, and some bricks have fallen, exposing the lining paper and framing below. The driveway is cracked and covered in liquefaction. The photographer comments, "These photos show our old house in River Rd and recovery work around Richmond and St Albans. Does that wall look straight to you?

Images, eqnz.chch.2010

There are occasional sewerage spills into the Avon River while all the sewer and road repairs are carried out. This rock wall was level and well above high tide level prior to the eathquakes. All the houses that can been seen here (except for those on the distant Port Hills) are in the suburban "red zone" and are still to be demolished.

Images, eqnz.chch.2010

The area beside the lower Avon River in New Brighton of Evans Avenue and Admirals Way has been cleared of houses and boundary fences (there were between 15 and 20 houses on this block) , fully fenced with post and wire and "spray on" grass applied. These were all red zone properties acquired by the crown after the land was deemed too damaged t...

Images, eqnz.chch.2010

A month after the 1st anniversary of the deadly Christchurch earthquake (22/02/11) a road cone lies on New Brighton Road, alongside the Avon River. Part of the earthquake 1st anniversary remembrance was for people to place flowers in road cones (and there are hundreds of thousands in the city). Many had flowers in them, as this one did. Photo ...

Research papers, University of Canterbury Library

The Canterbury region of New Zealand experienced a sequence of strong earthquakes during 2010-2011. Responses included government acquisition of many thousands of residential properties in the city of Christchurch in areas with severe earthquake effects. A large and contiguous tract of this ‘red zoned’ land lies in close proximity to the Ōtākaro / Avon River and is known as the Avon-Ōtākaro Red Zone (AORZ). The focus of this study was to provide an overview of the floodplain characteristics of the AORZ and review of international experience in ecological restoration of similar river margin and floodplain ecosystems to extract restoration principles and associated learnings. Compared to pre-earthquake ground levels, the dominant trend in the AORZ is subsidence, together with lateral movement especially in the vicinity of waterway. An important consequence of land subsidence in the lower Ōtākaro / Avon River is greater exposure to flooding and the effects of sea level rise. Scenario modelling for sea level rise indicates that much of the AORZ is exposed to inundation within a 100 year planning horizon based on a 1 m sea level rise. As with decisions on built infrastructure, investments in nature-based ‘green infrastructure’ also require a sound business case including attention to risks posed by climate change. Future-proofing of the expected benefits of ecological restoration must therefore be secured by design. Understanding and managing the hydrology and floodplain dynamics are vital to the future of the AORZ. However, these characteristics are shared by other floodplain and river restoration projects worldwide. Identifying successful approaches provides a useful a source of useful information for floodplain planning in the AORZ. This report presents results from a comparative case study of three international examples to identify relevant principles for large-scale floodplain management at coastal lowland sites.

Images, Alexander Turnbull Library

The cartoon shows a flag which looks rather like that of both Australia and New Zealand but not exactly like either; the Union Jack is half out of the top left corner and there are just three of New Zealand's four red stars and three of Australia's white stars. The cartoonist's title is 'Aust NZ united in tragedy'. Context - The Queensland floods of December 2010 to January 2011. Colour and black and white versions available. Quantity: 2 digital cartoon(s).

Audio, Radio New Zealand

A review of the week's news including: Labour struggling to put a dent in the National Party's lead in the polls, questions over Israelis caught up in the Christchurch earthquake, the latest from the Pike River Mine inquiry, electricity price rises fuelling inflation, an Auckland school wanting all students to take an iPad to class and Steve Williams dropped as Tiger Wood's caddy.

Articles, UC QuakeStudies

Photograph captioned, "Dallington used to be the most popular suburb in New Zealand to live in. And that makes sense, because it's halfway between the beach and the city. It's close enough to town but far enough away, as well. There were good schools in the area. The mall was close. It's got the river and the tree lined sections, everything. It was special all right".

Images, UC QuakeStudies

Two people examine damage to a house in Richmond. The brick wall is badly cracked and twisted, and some bricks have fallen, exposing the lining paper and framing below. The photographer comments, "These photos show our old house in River Rd and recovery work around Richmond and St Albans. The near wall is leaning at an alarming angle. I didn't like walking past it".

Images, UC QuakeStudies

A group of residents stand talking on the footpath beside River Road. The photographer comments, "Our neighbours were mostly already displaced by the Sep 4 2010 quakes. We all happened to arrive at the same time, so we had a good chat. From L-R; Deidre Crichton (389), Julie and Philip Cheyne (391), Marike Begg (363), Susannah and Kim Collins (383), Andy Corbin (389)".

Images, UC QuakeStudies

A wooden house in Wainoni has visibly bowed inwards towards its centre. The photographer comments, "During the numerous earthquakes in Christchurch the land which ran alongside the Avon river on Avonside Drive slumped towards the waterway. In a line parallel to the road the road, but around 20m away a ground movement occurred which caused some houses to rise up or sink down".

Audio, Radio New Zealand

A proposal to put houses back into Christchurch red zones is being shot down by some worried locals who say it's unfair and potentially unsafe. On Friday the crown-led agency, Regenerate Christchurch, released ten options for one area by the Avon river that 9 thousand people used to call home. Almost every house in the 602 hectare zone was demolished after the earthquakes.

Images, eqnz.chch.2010

The flooded Bexley Wetlands, now about 1 - 1.5metre below pre earthquake level. The short length of fence (mid ground) was on the "river track" that the council closed about three years ago. The whole track in this view is now under about 500mm water at high tide. The main track in front of the houses was, prior to earthquakes, below the leve...

Images, eqnz.chch.2010

Prior to the earthquakes (mainly the February 22 2011 event) this park bench was at track level. Shortly after the February quake someone in the council did the sums and realised that the area near the Avon River had dropped between a metre and 1.4m (about 4 foot), so a rush job by contractors shifted in many tonnes of rock and gravel to raise a...

Images, eqnz.chch.2010

The permanent closure (to motor vehicles) of the Bexley red zone streets has started. This was once the main south-north route just west of the Avon River in the New Brighton area, till an expressway (ring road) was built about 80m to the west (right) about 12-13 years ago. Then it became just another suburban street, but now all the houses ...

Research Papers, Lincoln University

Prognostic modelling provides an efficient means to analyse the coastal environment and provide effective knowledge for long term urban planning. This paper outlines how the use of SWAN and Xbeach numerical models within the ESRI ArcGIS interface can simulate geomorphological evolution through hydrodynamic forcing for the Greater Christchurch coastal environment. This research followed the data integration techniques of Silva and Taborda (2012) and utilises their beach morphological modelling tool (BeachMM tool). The statutory requirements outlined in the New Zealand Coastal Policy Statement 2010 were examined to determine whether these requirements are currently being complied with when applying the recent sea level rise predictions by the Intergovernmental Panel on Climate Change (2013), and it would appear that it does not meet those requirements. This is because coastal hazard risk has not been thoroughly quantified by the installation of the Canterbury Earthquake Recovery Authority (CERA) residential red zone. However, the Christchurch City Council’s (CCC) flood management area does provide an extent to which managed coastal retreat is a real option. This research assessed the effectiveness of the prognostic models, forecasted a coastline for 100 years from now, and simulated the physical effects of extreme events such as storm surge given these future predictions. The results of this research suggest that progradation will continue to occur along the Christchurch foreshore due to the net sediment flux retaining an onshore direction and the current hydrodynamic activity not being strong enough to move sediment offshore. However, inundation during periods of storm surge poses a risk to human habitation on low lying areas around the Avon-Heathcote Estuary and the Brooklands lagoon similar to the CCC’s flood management area. There are complex interactions at the Waimakariri River mouth with very high rates of accretion and erosion within a small spatial scale due to the river discharge. There is domination of the marine environment over the river system determined by the lack of generation of a distinct river delta, and river channel has not formed within the intertidal zone clearly. The Avon-Heathcote ebb tidal delta aggrades on the innner fan and erodes on the outer fan due to wave domination. The BeachMM tool facilitates the role of spatial and temporal analysis effectively and the efficiency of that performance is determined by the computational operating system.