
Damage to TJ's Kazbah in New Brighton. The east and north walls and part of the upper floor have collapsed, tipping rubble and the contents of the rooms out onto the street. The photographer comments, "The occupants of the business and rooms all managed to escape alive. A digger was used to make the building safe and then used to sift through the rubble for any surviving belongings. It was a very emotional time for the ex-occupants".
One of the less understood geotechnical responses to the cyclic loading from the MW6.2 Christchurch Earthquake, on the 22nd of February 2011, is the fissuring in the loessial soil-mantled, footslope positions of the north-facing valleys of the Port Hills. The fissures are characterized by mostly horizontal offset (≤500mm), with minor vertical displacement (≤300mm), and they extend along both sides of valleys for several hundred metres in an approximately contour-parallel orientation. The fissure traces correspond to extensional features mapped in other studies. Previous studies have suggested that the fissures are the headscarps of incipient landslides, but the surface and subsurface features are not typical of landslide movement. Whilst there are some features that correlate with landslide movement, there are many features that contradict the landslide movement hypothesis. Of critical importance to this investigation was the fact that there are no landslide flanks, there has been no basal shear surface found, there is little deformation in the so-called ‘landslide body’, and there have been no recorded zones of low shear strength in the soil deposit that are indicative of a basal shear surface. This thesis is a detailed geotechnical study on the fissures along part of Ramahana Road in the Hillsborough Valley, Christchurch. Shallow and deep investigation methods found that the predominant soil is loess-colluvium, to depths of ~20m, and this soil has variable geotechnical characteristics depending on the layer sampled. The factor that has the most influence on shear strength was found to be the moisture content. Direct shear-box testing of disturbed, recompacted loess-colluvium found that the soil had a cohesion of 35-65kPa and a friction angle of 38-43° when the soil moisture content was at 8-10%. However when the moisture content was at 19-20% the soil’s cohesion decreased to 3-5kPa and its friction angle decreased to 33-38°, this moisture content is at or slightly above the plastic limit. An electrical resistivity geophysical survey was conducted perpendicular to multiple fissure traces and through the compressional zone at 17 Ramahana Road. The electrical resistivity line found that there was an area of high resistivity at the toe of the slope, and an area of high conductivity downslope of this and at greater depths. This area correlated to the compressional zone recorded by previous studies. Moisture content testing of the soil in these locations showed that the soil in the resistive area was relatively dry (9%) compared to the surrounding soil (13%), whilst the soil in the conductive area was relatively wet (22%)compared to the surrounding soil (19%). Density tests of the soil in the compressional zone recorded that the resistive area had a higher dry density than the surrounding soil (~1790 kg/m3 compared to ~1650 kg/m3). New springs arose downslope of the compressional zone contemporaneously with the fissures, and it is interpreted that these have arisen from increased hydraulic head in the Banks Peninsula bedrock aquifer system, and earthquake induced-bedrock fracturing. A test pit was dug across an infilled fissure trace at 17 Ramahana Road to a depth of 3m. The fissure trace had an aperture of 450-470mm at the ground surface, but it gradually lost aperture with depth until 2.0-2.1m where it became a segmented fissure trace with 1-2mm aperture. A mixed-colluvium layer was intercepted by the fissure trace at 2.4m depth, and there was no observable vertical offset of this layer. The fissure trace was at an angle of 78° at the ground surface, but it also flattened with depth, which gave it a slightly curved appearance. The fissure trace was at an assumed angle of 40-50° near the base of the test pit. Rotational slide, translational slide and lateral spread landslide movement types were compared and contrasted as possibilities for landslide movement types, whilst an alternative hypothesis was offered that the fissures are tensile failures with a quasi-toppling motion involving a cohesive block of loessial soil moving outwards from the slope, with an accommodating compressional strain in the lower less cohesive soil. The mechanisms behind this movement are suggested to be the horizontal earthquake inertia forces from the Christchurch Earthquake, the static shear stress of the slope, and bedrock uplift of the Port Hills in relation to the subsidence of the Christchurch city flatlands. Extremely high PGA is considered to be a prerequisite to the fissure trace development, and these can only be induced in the Hillsborough Valley from a Port Hills Fault rupture, which has a recurrence interval of ~10,000 years. The current understanding of how the loess-colluvium soil would behave under cyclic loading is limited, and the mechanisms behind the suggested movement type are not completely understood. Further research is needed to confirm the proposed mechanism of the fissure traces. Laboratory tests such as the cyclic triaxial and cyclic shear test would be beneficial in future research to quantitatively test how the soil behaves under cyclic loading at various moisture contents and clay contents, and centrifuge experiments would be of great use to qualitatively test the suggested mode of movement in the loessial soil.
Following the 22nd February 2011, Mw 6.2 earthquake located along a previously unknown fault beneath the Port Hills of Christchurch, surface cracking was identified in contour parallel locations within fill material at Quarry Road on the lower slopes of Mount Pleasant. GNS Science, in the role of advisor to the Christchurch City Council, concluded that these cracks were a part of a potential rotational mass movement (named zone 11A) within the fill and airfall loess material present. However, a lack of field evidence for slope instability and an absence of laboratory geotechnical data on which slope stability analysis was based, suggested this conclusion is potentially incorrect. It was hypothesised that ground cracking was in fact due to earthquake shaking, and not mass movement within the slope, thus forming the basis of this study. Three soil units were identified during surface and subsurface investigations at Quarry Road: fill derived from quarry operations in the adjacent St. Andrews Quarry (between 1893 and 1913), a buried topsoil, and underlying in-situ airfall loess. The fill material was identified by the presence of organic-rich topsoil “clods” that were irregular in both size (∼10 – 200 mm) and shape, with variable thicknesses of 1 – 10 m. Maximum thickness, as indicated by drill holes and geophysical survey lines, was identified below 6 Quarry Road and 7 The Brae where it is thought to infill a pre-existing gully formed in the underlying airfall loess. Bearing strength of the fill consistently exceeded 300 kPa ultimate below ∼500 mm depth. The buried topsoil was 200 – 300 mm thick, and normally displayed a lower bearing strength when encountered, but not below 300 kPa ultimate (3 – 11 blows per 100mm or ≥100 kPa allowable). In-situ airfall loess stood vertically in outcrop due to its characteristic high dry strength and also showed Scala penetrometer values of 6 – 20+ blows per 100 mm (450 – ≥1000 kPa ultimate). All soils were described as being moist to dry during subsurface investigations, with no groundwater table identified during any investigation into volcanic bedrock. In-situ moisture contents were established using bulk disturbed samples from hand augers and test pitting. Average moisture contents were low at 9% within the fill, 11 % within the buried topsoil, and 8% within the airfall loess: all were below the associated average plastic limit of 17, 15, and 16, respectively, determined during Atterberg limit analysis. Particle size distributions, identified using the sieve and pipette method, were similar between the three soil units with 11 – 20 % clay, 62 – 78 % silt, and 11 – 20 % fine sand. Using these results and the NZGS soil classification, the loess derived fill and in-situ airfall loess are termed SILT with some clay and sand, and the buried topsoil is SILT with minor clay and sand. Dispersivity of the units was found using the Emerson crumb test, which established that the fill can be non- to completely dispersive (score 0 – 4). The buried topsoil was always non-dispersive (score 0), and airfall loess completely dispersive (score 4). Values for cohesion (c) and internal friction angle (φ) of the three soil units were established using the direct shear box at field moisture contents. Results showed all soil units had high shear strengths at the moisture contents tested (c = 18 – 24 kPa and φ = 42 – 50°), with samples behaving in a brittle fashion. Moisture content was artificially increased to 16% within the buried topsoil, which reduced the shear strength (c = 10 kPa, φ = 18°) and allowed it to behave plastically. Observational information indicating stability at Quarry Road included: shallow, discontinuous, cracks that do not display vertical offset; no scarp features or compressional zones typical of landsliding; no tilted or deformed structures; no movement in inclinometers; no basal shear zone identified in logged core to 20 m depth; low field moisture contents; no groundwater table; and high soil strength using Scala penetrometers. Limit equilibrium analysis of the slope was conducted using Rocscience software Slide 5.0 to verify the slope stability identified by observational methods. Friction, cohesion, and density values determined during laboratory were input into the two slope models investigated. Results gave minimum static factor of safety values for translational (along buried topsoil) and rotational (in the fill) slides of 2.4 – 4.2. Sensitivity of the slope to reduced shear strength parameters was analysed using c = 10 kPa and φ = 18° for the translational buried topsoil plane, and a cohesion of 0 kPa within the fill for the rotational plane. The only situation that gave a factor of safety <1.0 was in nonengineered fill at 0.5 m depth. Pseudostatic analysis based on previous peak ground acceleration (PGA) values for the Canterbury Earthquake Sequence, and predicted PGAs for future Alpine Fault and Hope Fault earthquakes established minimum factor of safety values between 1.2 and 3.3. Yield acceleration PGAs were computed to be between 0.8g and 1.6g. Based on all information gathered, the cracking at Quarry Road is considered to be shallow deformation in response to earthquake shaking, and not due to deep-seated landsliding. It is recommended that the currently bare site be managed by smoothing the land, installing contour drainage, and bioremediation of the surface soils to reduce surface water infiltration and runoff. Extensive earthworks, including removal of the fill, are considered unnecessary. Any future replacement of housing would be subject to site-specific investigations, and careful foundation design based on those results.
Photograph captioned by Fairfax, "Chris Lin and his wife Caleen Xue at the door of their cool store safe where they slept for three weeks after the 4 September earthquake to guard what was left of their stock, while their teenage children rented a single room in a house up the road for their safety".
The number of speed camera tickets being issued skyrockets, police say it's about road safety, the AA's not so sure. Crisis talks in Europe over the Greek debt crisis... and its impact on the Eurozone and there were angry scenes at a Christchurch meeting last night as residents tried to stop a dump for earthquake debris being built in their suburb.
The New Zealand Shipping Federation says the government needs to take the resilience of ports seriously as the Kaikoura earthquake has shown the vulnerability of roading - and consider what their role is when auditing them. Annabel Young is the Executive Director of the NZ Shipping Federation. Canterbury University Professor of Geological Sciences Tim Davies, says improving and increasing the transport network through coastal shipping is essential.
Tomorrow will mark four years since a huge 7.8 magnitude earthquake rocked North Canterbury. As well as severely damaging homes and roads, it left some hill country farms in the area with up to 40 percent of their land unusable. Four years on, sheep and beef farmers are finding new ways to work. Rural reporter, Maja Burry and cameraman Nate McKinnon have the story.
Photograph captioned by Fairfax, "Chris Lin and his wife Caleen Xue at the door of their cool store safe where they slept for three weeks after the 4 September earthquake to guard what was left of their stock, while their teenage children rented a single room in a house up the road for their safety".
Photograph captioned by Fairfax, "Christchurch Earthquake. University student Sam Johnson organised through Facebook students to go into the suburbs to help residents clean up after Saturday morning's earthquake. They gathered in Halswell to help residents clean up the silt from their properties. James Litchwark (L) and James Wigzell shovel dirt from 2A Larsons Road, Halswell".
The farmer swore that his fence was erected in a straingt line, but mother nature had other ideas! Aftermath of the Saturday 4 September 2010 magnitude 7.1 earthquake at the previously unknown faultline along which the quake originated.
The farmer swore that his hedge was planted in a straingt line, but mother nature had other ideas! Aftermath of the Saturday 4 September 2010 magnitude 7.1 earthquake at the previously unknown faultline along which the quake originated.
The farmer swore that his fence was erected in a straingt line, but mother nature had other ideas! Aftermath of the Saturday 4 September 2010 magnitude 7.1 earthquake at the previously unknown faultline along which the quake originated.
A view down Beresford Street in New Brighton, looking west towards the city at sunset. The photographer comments, "On the other side of the Avon river from New Brighton is the Bexley red zone. Here numerous earthquake damaged streets of houses will be flattened due to it being to uneconomical in the current climate to repair the land to be suitable for housing. There is a campaign at the moment to try and convert all this red zone land, which is mainly adjacent to the Avon river to a giant park".
Photograph captioned by Fairfax, "Gorge Road School held a 'Red & Black' themed dress day and a gold coin donation (which they made into a coin trail) to raise funds for earthquake-stricken Canterbury. Pictured with their coins are Logan Marshall (5) on the left and Aaron Hart (6), with school pupils in behind. The fifty-pupil school managed to raise $136.00".
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".
Liquefaction in North New Brighton. The photographer comments, "This was the liquefaction pouring out of a split in the road where it joins the side-walk. The quakes felt pretty violent, but the damage was less severe than the February one. Unlucky for me the epicentre was only 9.6km away and smaller aftershocks were a lot closer".
Photograph captioned by Fairfax, "Christchurch Earthquake. A massive 7.4 magnitude earthquake has hit Christchurch and the wider South Island, causing widespread damage, two serious injuries and power cuts to most of the city. Anna Lipsham begins the clean up at Ashton, Wheelans and Hegan in Kaiapoi. Lipsham empties dirt from the building into a large fissure in the road".
Photograph captioned by Fairfax, "Christchurch Earthquake. A massive 7.4 magnitude earthquake has hit Christchurch and the wider South Island, causing widespread damage, two serious injuries and power cuts to most of the city. Anna Lipsham begins the clean up at Ashton, Wheelans and Hegan in Kaiapoi. Lipsham empties dirt from the building into a large fissure in the road".
Photograph captioned by Fairfax, "Christchurch Earthquake. A massive 7.4 magnitude earthquake has hit Christchurch and the wider South Island, causing widespread damage, two serious injuries and power cuts to most of the city. Warren Lipsham begins the clean up at Ashton, Wheelans and Hegan in Kaiapoi. Lipsham empties dirt from the building into a large fissure in the road".
The only Christchurch street still closed following the 2011 earthquake will reopen later in 2018 only to close again in 2019 so the council can extend the route for the tram. The proposal has raised the ire of fledgling businesses along High st worried about the disruption the road works will cause them and wanting the work done now, before they open their doors to the public.
The farmer swore that his fence and hedge were in a straingt line, but mother nature had other ideas! Aftermath of the Saturday 4 September 2010 magnitude 7.1 earthquake at the previously unknown faultline along which the quake originated.
This is the pedestrian bridge in Kaiapoi close to Christchurch. Not the best angle but the whole bridge on the right hand side is twisted and looks like some kind of rollercoaster. Taken one month after the Quake Twitter |
There are quite a few signs like this around Christchurch after the Quake. This is one of them. Off shot to the right is a leveled patch of ground where the owners furniture restoration shop used to be. Twitter |
Refers to the reopening of the Christchurch strip club 'Calendar Girls' after more than a year inside the central-city cordon. The building suffered minimal damage but was inaccessible because damage to neighbouring buildings meant the road (Hereford Street) were closed. Quantity: 1 digital cartoon(s).
The Cranmer Court building, on the corner of Kilmore and Montreal Streets, after the 22 February 2011 earthquake. Large pieces of the building have collapsed, including the octagonal corner section that housed Plato Creative from March 2008 to November 2009. Masonry has fallen onto the footpath and road, and the site has been enclosed in a safety fence to keep people away. The whitewashed interior walls of one of the apartments can be seen.
Christchurch is still struggling 10 years on from the earthquake with vacant spaces and little development. In the surrounding areas of Christchurch in Selwyn, inland and in the Waimakariri District to the north it's boom times, with the councils unable to keep up with building consents. The regions have continued to grow over the last 10 years after people initially moved there after the earthquake to escape the bumpy roads, red zones and EQC battles. RNZ's Sally Murphy reports.
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. Pictured from left are Trooper Jesse Gaffney (ex-Timaru), St Andrews Police Constable Tim Hartnell and Constable Cath Hone of Timaru. They have been posted around Christchurch road blocks over the last week. They are pictured at the Manchester and Tuam cordon".
An access point into the CBD cordon at the corner of Gloucester and Oxford Terrace. Road cones and fencing can be seen in the background with a sign saying 'Access point. Hours of operation 6am-7pm daily. Outside this house use Manchester St/Cambridge Terrace access point'. Inside the cordon, a station can be seen on the left, as well as some workers and cars. The demolition site at the back is where the Brannigans Building used to be.
A PDF copy of pages 214-215 of the book Christchurch: The Transitional City Pt IV. The pages document the transitional project 'Christchurch: A Board Game'. Photo (top): Peter Walker, Three Chairs Photography. With permission from Volunteer Army Foundation. Photo (bottom): Irene Boles.
A photograph captioned, "We get the young fellas to come in and do the upkeep on the government houses that have been sold. They cut down all the long grass and just tidy up all the fire risk sections. This one's easier cos the house is gone. If you keep it tidy it looks tidy from the road. There's people living here, and there's nothing worse than looking over your house and seeing grass this high".