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Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team standing on the bank of the Avon River. In the background are the remains of the collapsed PGC Building. An excavator is on top of these remains, working to clear them away.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team standing on the bank of the Avon River. In the background are the remains of the collapsed PGC Building. An excavator is on top of these remains, working to clear them away.

Images, UC QuakeStudies

Detail of damage to a house in Richmond. The brick wall is badly cracked and twisted. The photographer comments, "These photos show our old house in River Rd and recovery work around Richmond and St Albans. More ruptured brickwork".

Images, UC QuakeStudies

An earthquake-damaged bridge, the approach to which has slumped. The photographer comments, "Due to lateral spread and the land slumping the road leading to this bridge has moved down greatly. Just imagine making the street lamps upright and how much that section of road would rise up at the end. When you go over bridges in the east side of Christchurch it is quite a climb up and a big drop down on the other side. The bridges in most cases coped very well, but not so the land leading to them".

Images, UC QuakeStudies

A string quartet from Christchurch Girls High School plays on the riverbank before the River of Flowers event held in Riccarton Bush, commemorating the second anniversary of the 22 February earthquake. In the foreground people wait for the event to start.

Images, UC QuakeStudies

A string quartet from Christchurch Girls High School plays on the riverbank before the River of Flowers event held in Riccarton Bush, commemorating the second anniversary of the 22 February earthquake. In the foreground people wait for the event to start.

Images, UC QuakeStudies

A view over the Avon river, looking at the Boulevard Restaurant and Bar. The canopy over the outside seating area has been distorted, and on the doors are spray painted codes left by USAR after the building had been cleared.

Research papers, University of Canterbury Library

Spatial variations in river facies exerted a strong influence on the distribution of liquefaction features observed in Christchurch during the 2010-11 Canterbury Earthquake Sequence (CES). Liquefaction and liquefaction-induced ground deformation was primarily concentrated near modern waterways and areas underlain by Holocene fluvial deposits with shallow water tables (< 1 to 2 m). In southern Christchurch, spatial variations of liquefaction and subsidence were documented in the suburbs within inner meander loops of the Heathcote River. Newly acquired geospatial data, geotechnical reports and eye-witness discussions are compiled to provide a detailed account of the surficial effects of CES liquefaction and ground deformation adjacent to the Heathcote River. LiDAR data and aerial photography are used to produce a new series of original figures which reveal the locations of recurrent liquefaction and subsidence. To investigate why variable liquefaction patterns occurred, the distribution of surface ejecta and associated ground damage is compared with near-surface sedimentologic, topographic, and geomorphic variability to seek relationships between the near-surface properties and observed ground damages. The most severe liquefaction was concentrated within a topographic low in the suburb of St Martins, an inner meander loop of the Heathcote River, with liquefaction only minor or absent in the surrounding areas. Subsurface investigations at two sites in St Martins enable documentation of fluvial stratigraphy, the expressions of liquefaction, and identification of pre-CES liquefaction features. Excavation to water table depths (~1.5 m below the surface) across sand boils reveals multiple generations of CES liquefaction dikes and sills that cross-cut Holocene fluvial and anthropogenic stratigraphy. Based on in situ geotechnical tests (CPT) indicating sediment with a factor of safety < 1, the majority of surface ejecta was sourced from well-sorted fine to medium sand at < 5 m depth, with the most damaging liquefaction corresponding with the location of a low-lying sandy paleochannel, a remnant river channel from the Holocene migration of the meander in St Martins. In the adjacent suburb of Beckenham, where migration of the Heathcote River has been laterally confined by topography associated with the volcanic lithologies of Banks Peninsula, severe liquefaction was absent with only minor sand boils occurring closest to the modern river channel. Auger sampling across the suburb revealed thick (>1 m) clay-rich overbank and back swamp sediments that produced a stratigraphy which likely confined the units susceptible to liquefaction and prevented widespread ejection of liquefied material. This analysis suggests river migration promotes the formation and preservation of fluvial deposits prone to liquefaction. Trenching revealed the strongest CES earthquakes with large vertical accelerations favoured sill formation and severe subsidence at highly susceptible locations corresponding with an abandoned channel. Less vulnerable sites containing deeper and thinner sand bodies only liquefied in the strongest and most proximal earthquakes forming minor localised liquefaction features. Liquefaction was less prominent and severe subsidence was absent where lateral confinement of a Heathcote meander has promoted the formation of fluvial stratum resistant to liquefaction. Correlating CES liquefaction with geomorphic interpretations of Christchurch’s Heathcote River highlights methods in which the performance of liquefaction susceptibility models can be improved. These include developing a reliable proxy for estimating soil conditions in meandering fluvial systems by interpreting the geology and geomorphology, derived from LiDAR data and modern river morphology, to improve the methods of accounting for the susceptibility of an area. Combining geomorphic interpretations with geotechnical data can be applied elsewhere to identify regional liquefaction susceptibilities, improve existing liquefaction susceptibility datasets, and predict future earthquake damage.

Images, UC QuakeStudies

A digitally manipulated photograph of the badly twisted Medway Street footbridge. The photographer comments, "This bridge over the Avon River in Christchurch, New Zealand has been left in place since the first major earthquake back in September 2010. Graffiti artists or taggers are still leaving their marks on it even though it is nearly twisted at 90 degrees at one point".

Images, UC QuakeStudies

A photograph of a warning sign placed next to a river in Christchurch. The sign reads, "Warning contaminated water. Due to sewage overflows this water is unsafe to human contact and activity and a public health risk. Please keep all people and pets out of contact with the water and do not consume any seafood or shellfish collected from this area".

Images, UC QuakeStudies

Damage to Fitzgerald Avenue. The northbound lanes have collapsed towards the river, and a pile of rubble from the damaged road is heaped on the road. Road cones divert traffic onto the southbound lanes. The photographer comments, "Fitzgerald Avenue between Kilmore Street and Bealey Ave is a mess. Half of the road has slumped towards the river by a good metre or two. My brother-in-law was here when the 22nd earthquake hit and he said the damage wasn't as bad as this at first. A local resident told me that the road is slumping more and more each day".

Images, UC QuakeStudies

Damage to Fitzgerald Avenue. The northbound lanes have collapsed towards the river, and a pile of rubble from the damaged road is heaped on the road. Road cones divert traffic onto the southbound lanes. The photographer comments, "Fitzgerald Avenue between Kilmore Street and Bealey Ave is a mess. Half of the road has slumped towards the river by a good metre or two. My brother-in-law was here when the 22nd earthquake hit and he said the damage wasn't as bad as this at first. A local resident told me that the road is slumping more and more each day".

Images, UC QuakeStudies

Damage to Fitzgerald Avenue. The northbound lanes have collapsed towards the river, and a pile of rubble from the damaged road is heaped on the road. Road cones divert traffic onto the southbound lanes. The photographer comments, "Fitzgerald Avenue between Kilmore Street and Bealey Ave is a mess. Half of the road has slumped towards the river by a good metre or two. My brother-in-law was here when the 22nd earthquake hit and he said the damage wasn't as bad as this at first. A local resident told me that the road is slumping more and more each day".

Images, UC QuakeStudies

A photograph of contractor Tony Fisher of Fisher Agricultural Ltd. inspecting 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.