A zone of active tectonism occurs in mid and north Canterbury, from the Rakaia to the Waipara Rivers, which coincides with seismicity concentrations and several Quaternary surface anomalies and is here defined as the Porters Pass Tectonic Zone. Although parallel to the Marlborough faults to the north, the lack of regional definition suggests this zone is much younger in its inception reflecting a southward movement of the plate rotation vector. The objectives of this study were to map the structures associated with this zone in the segment between the Rakaia and Waimakariri Rivers with detailed analysis concentrated in the upper Kawai Valley. Quaternary offsets on the main lineament of the Porters Pass Fault were traced through the area and evidence for the rate of movement, probable magnitudes and return periods of related seismic events was sought. The basement was found to be complicated by pre-existing deformation structures in Torlesse Group rocks which have been subsequently been re-activated or rotated by recent fault movement probably beginning in the Pleistocene. This phase is dominantly thrusting and uplift has lead to the erosion of most of the overlying sedimentary cover. Remnants of the Cret-Tertiary sediments still remain as fault-bounded packets. Evidence suggests that a change to development of a regional lateral shear associated with the Porters Pass Tectonic Zone transects the thrust system with complex interaction between the older reverse and new strike-slip faults. Offset rates along the segments of the Porters Pass Fault are not well constrained but are believed to be approximately in the range of 11-13 mm/year for at least the last 130,000 years. This rate is similar to other large faults in the Marlborough region. Two earthquake events have been identified and dated at 600 and 2000 years ago, with a magnitude of greater than 6.5. Evidence suggests characteristic earthquakes along the Porters Pass Fault are greater than Magnitude 7. This result has some major ramifications for the expected seismic hazards for nearby Christchurch.
This paper presents a seismic velocity model of Canterbury, New Zealand based on 3D geologic surfaces and velocities from a range of data sources. The model provides the 3D crustal structure in the region at multiple length scales for seismic wave propagation simulations, such as broadband ground motion and shallow site response analyses related to understanding the ground motions and site responses during the 2010- 2011 Canterbury earthquakes. Pre-Quaternary geologic horizons are calculated based on the reinterpretation of a comprehensive network of seismic reflection surveys from seven different campaigns over the past 50 years, as well as point constraints across an array of petroleum industry drill holes. Particular attention is given to a detailed representation of Quaternary stratigraphy, representing shallow (z<250m) near-surface layers in the model. Seismic velocities are obtained from seismic reflection processing (for Vp) and also recently performed active and passive surface wave analyses (for Vs). Over 1,700 water wells in the region are used to constrain the complex inter-bedded Quaternary stratigraphy (gravels, sands, silts, organics etc.) near the coastline, including beneath urban Christchurch, which has resulted from fluvial deposition and marine regression and transgression. For the near-surface Springston and Christchurch Formations in the Christchurch urban area (z<50m), high-spatial resolution seismic velocities (including Vs30 ) were obtained from over 13,000 cone penetration tests combined with a recently developed CPT-Vs correlation.
A 3D high-resolution model of the geologic structure and associated seismic velocities in the Canterbury, New Zealand region is developed utilising data from depthconverted seismic reflection lines, petroleum and water well logs, cone penetration tests, and implicitly guided by existing contour maps and geologic cross sections in data sparse subregions. The model, developed using geostatistical Kriging, explicitly represents the significant and regionally recognisable geologic surfaces that mark the boundaries between geologic units with distinct lithology and age. The model is examined in the form of both geologic surface elevation contour maps as well as vertical cross sections of shear wave velocity, with the most prominent features being the Banks Peninsula Miocene-Pliocene volcanic edifice, and the Pegasus and Rakaia late Mesozoic-Neogene sedimentary basins. The adequacy of the modelled geologic surfaces is assessed through a residual analysis of point constraints used in the Kriging and qualitative comparisons with previous geologic models of subsets of the region. Seismic velocities for the lithological units between the geologic surfaces have also been derived, thus providing the necessary information for a Canterbury velocity model (CantVM) for use in physics-based seismic wave propagation. The developed model also has application for the determination of depths to specified shear wave velocities for use in empirical ground motion modelling, which is explicitly discussed via an example.
Blog of Julian, educational outreach facilitator at GNS Science. Includes information on GNS Science field trips; explanations of New Zealand geology; video clips; and sections on the Christchurch earthquakes, and New Zealand fossils.
Provides news and information to residents of Canterbury after the 2010 and 2011 earthquakes. Includes ideas discussion page, blog, services directory, list of damaged suburbs, geological information including recent aftershocks, and photos.
Deep shear wave velocity (Vs) profiles (>400 m) were developed at 14 sites throughout Christchurch, New Zealand using surface wave methods. This paper focuses on the inversion of surface wave data collected at one of these sites, Hagley Park. This site is located on the deep soils of the Canterbury Plains, which consist of alluvial gravels inter-bedded with estuarine and marine sands, silts, clays and peats. Consequently, significant velocity contrasts exist at the interface between geologic formations. In order to develop realistic velocity models in this complex geologic environment, a-priori geotechnical and geologic data were used to identify the boundaries between geologic formations. This information aided in developing the layering for the inversion parameters. Moreover, empirical reference Vs profiles based on material type and confining pressure were used to develop realistic Vs ranges for each layer. Both the a-priori layering information and the reference Vs curves proved to be instrumental in generating realistic velocity models that account for the complex inter-bedded geology in the Canterbury Plains.
Provides a map, the geological background, describes the effects, both in Christchurch and its surrounding areas, the damage to notable buildings, the financial exposure, the emergency response and relief efforts and the media coverage of the earthquake.
Erosion to earthquakes with geologist and paleontologist Dr Hamish Campbell from GNS science. Chatham Islands geology and it's links with Christchurch and Canterbury.
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The Mw 7.8 Kaikōura earthquake ruptured ~200 km at the ground surface across the New Zealand plate boundary zone in the northern South Island. This study was conducted in an area of ~600 km2 in the epicentral region where the faults comprise two main non-coplanar sets that strike E-NE and NNE-NW with mainly steep dips (60о-80°). Analysis of the surface rupture using field and LiDAR data provides new information on the dimensions, geometries and kinematics of these faults which was not previously available from pre-earthquake active faults or bedrock structure. The more northerly striking fault set are sub-parallel to basement bedding and accommodated predominantly left-lateral reverse slip with net slips of ~1 and ~5 m for the Stone Jug and Leader faults, respectively. The E-NE striking Conway-Charwell and The Humps faults accrued right-lateral to oblique reverse with net slips of ~2 and ~3 m, respectively. The faults form a hard-linked system dominated by kinematics consistent with the ~260° trend of the relative plate motion vector and the transpressional structures recorded across the plate boundary in the NE South Island. Interaction and intersection of the main fault sets facilitated propagation of the earthquake and transfer of slip northwards across the plate boundary zone.
Surface rupture and slip from the Mw 7.8 2016 Kaikōura Earthquake have been mapped in the region between the Leader and Charwell rivers using field mapping and LiDAR data. The eastern Humps, north Leader and Conway-Charwell faults ruptured the ground surface in the study area. The E-NE striking ‘The Humps’ Fault runs along the base of the Mt Stewart range front, appears to dip steeply NW and intersects the NNW-NNE Leader Fault which itself terminates northwards at the NE striking Conway-Charwell Fault. The eastern Humps Fault is up to the NW and accommodates oblique slip with reverse and right lateral displacement. Net slip on ‘The Humps’ Fault is ≤4 m and produced ≤4 m uplift of the Mt Stewart range during the earthquake. The Leader Fault strikes NNW-NNE with dips ranging from ~10° west to 80° east and accommodated ≤4 m net slip comprising left-lateral and up-to-the-west vertical displacement. Like the Humps west of the study area, surface-rupture of the Leader Fault occurred on multiple strands. The complexity of rupture on the Leader Fault is in part due to the occurrence of bedding-parallel slip within the Cretaceous-Cenozoic sequence. Although the Mt Stewart range front is bounded by ‘The Humps’ Fault, in the study area neither this fault nor the Leader Fault were known to have been active before the earthquake. Fieldwork and trenching investigations are ongoing to characterise the geometry, kinematics and paleoseismic history of the mapped active faults.
Provides a map, the geological background, describes the effects, both in Christchurch and its surrounding areas, the damage to notable buildings, the financial exposure, the emergency response and relief efforts and the media coverage of the earthquake.
Dr. Mark Quiqley is Senior Lecturer in Active Tectonics and Geomorphology in the Department of Geological Sciences at the University of Canterbury. He is part of the team involved in the scientific response to the Canterbury earthquake and has been monitoring it from the air.
This paper provides a photographic tour of the ground-surface rupture features of the Greendale Fault, formed during the 4th September 2010 Darfield Earthquake. The fault, previously unknown, produced at least 29.5 km of strike-slip surface deformation of right-lateral (dextral) sense. Deformation, spread over a zone between 30 and 300 m wide, consisted mostly of horizontal flexure with subsidiary discrete shears, the latter only prominent where overall displacement across the zone exceeded about 1.5 m. A remarkable feature of this event was its location in an intensively farmed landscape, where a multitude of straight markers, such as fences, roads and ditches, allowed precise measurements of offsets, and permitted well-defined limits to be placed on the length and widths of the surface rupture deformation.
Sue Holmes, resident of Seabreeze Close in Bexley, which was built on reclaimed land which has liquefied after the Canterbury earthquake; Dr Tom Wilson, lecturer in Hazard and Disaster Management, from the department of Geological Sciences, Canterbury University; and Bob Parker, Mayor of Christchurch.
his poster presents the ongoing development of a 3D Canterbury seismic velocity model which will be used in physics-based hybrid broadband ground motion simulation of the 2010-2011 Canterbury earthquakes. Velocity models must sufficiently represent critical aspects of the crustal structure over multiple length scales which will influence the results of the simulations. As a result, numerous sources of data are utilized in order to provide adequate resolution where necessary. Figure 2: (a) Seismic reflection line showing P-wave velocities and significant geologic horizons (Barnes et al. 2011), and (b) Shear wave profiles at 10 locations (Stokoe et al. 2013). Figure 4: Cross sections of the current version of the Canterbury velocity model to depths of 10km as shown in Figure 1: (a) at a constant latitude value of -43.6˚, and (b) at a constant longitude value of 172.64˚. 3. Ground Surface and Geologic Horizon Models Figure 3: (a) Ground surface model derived from numerous available digital elevation models, and (b) Base of the Quaternary sediments derived from structural contours and seismic reflection line elevations. The Canterbury region has a unique and complex geology which likely has a significant impact on strong ground motions, in particular the deep and loose deposits of the Canterbury basin. The Canterbury basin has several implications on seismic wave phenomena such as long period ground motion amplification and wave guide effects. Using a realistic 3D seismic velocity model in physics-based ground motion simulation will implicitly account for such effects and the resultant simulated ground motions can be studied to gain a fundamental understanding of the salient ground motion phenomena which occurred during the Canterbury earthquakes, and the potential for repeat occurrences in the Canterbury region. Figure 1 shows the current model domain as a rectangular area between Lat=[-43.2˚,-44.0˚], and Lon=[171.5˚,173.0˚]. This essentially spans the area between the foot of the Southern Alps in the North West to Banks Peninsula in the East. Currently the model extends to a depth of 50km below sea level.
Since the early 1980s seismic hazard assessment in New Zealand has been based on Probabilistic Seismic Hazard Analysis (PSHA). The most recent version of the New Zealand National Seismic Hazard Model, a PSHA model, was published by Stirling et al, in 2012. This model follows standard PSHA principals and combines a nation-wide model of active faults with a gridded point-source model based on the earthquake catalogue since 1840. These models are coupled with the ground-motion prediction equation of McVerry et al (2006). Additionally, we have developed a time-dependent clustering-based PSHA model for the Canterbury region (Gerstenberger et al, 2014) in response to the Canterbury earthquake sequence. We are now in the process of revising that national model. In this process we are investigating several of the fundamental assumptions in traditional PSHA and in how we modelled hazard in the past. For this project, we have three main focuses: 1) how do we design an optimal combination of multiple sources of information to produce the best forecast of earthquake rates in the next 50 years: can we improve upon a simple hybrid of fault sources and background sources, and can we better handle the uncertainties in the data and models (e.g., fault segmentation, frequency-magnitude distributions, time-dependence & clustering, low strain-rate areas, and subduction zone modelling)? 2) developing revised and new ground-motion predictions models including better capturing of epistemic uncertainty – a key focus in this work is developing a new strong ground motion catalogue for model development; and 3) how can we best quantify if changes we have made in our modelling are truly improvements? Throughout this process we are working toward incorporating numerical modelling results from physics based synthetic seismicity and ground-motion models.
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.
University of Canterbury geologist Mark Quigley has earned a reputation for being a great science communicator on the subject of earthquakes. But when he's not in the media spotlight, he's out and about around Canterbury building a picture of the region's tectonic history, and trying to understand what might happen in the future.
This report summarizes the development of a region-wide surficial soil shear wave velocity (Vs ) model based on the unique combination of a large high-spatial-density database of cone penetration test (CPT) logs in the greater Christchurch urban area (> 15, 000 logs as of 1 February 2014) and the Christchurch-specific empirical correlation between soil Vs and CPT data developed by McGann et al. [1, 2]. This model has applications for site characterization efforts via maps of time-averaged Vs over specific depths (e.g. Vs30, Vs10), and for numerical modeling efforts via the identification of typical Vs profiles for different regions and soil behaviour types within Christchurch. In addition, the Vs model can be used to constrain the near-surface velocities for the 3D seismic velocity model of the Canterbury basin [3] currently being developed for the purpose of broadband ground motion simulation. The general development of these region-wide near-surface Vs models includes the following general phases, with each discussed in separate chapters of this report. • An evaluation of the available CPT dataset for suitability, and the definition of other datasets and assumptions necessary to characterize the surficial sediments of the region to 30 m depth. • The development of time-averaged shear wave velocity (Vsz) surfaces for the Christchurch area from the adopted CPT dataset (and supplementary data/assumptions) using spatial interpolation. The Vsz surfaces are used to explore the characteristics of the near-surface soils in the regions and are shown to correspond well with known features of the local geology, the historical ecosystems of the area, and observations made following the 2010- 2011 Canterbury earthquakes. • A detailed analysis of the Vs profiles in eight subregions of Christchurch is performed to assess the variablity in the soil profiles for regions with similar Vsz values and to assess Vsz as a predictive metric for local site response. It is shown that the distrubution of soil shear wave velocity in the Christchurch regions is highly variable both spatially (horizontally) and with depth (vertically) due to the varied geological histories for different parts of the area, and the highly stratified nature of the nearsurface deposits. This variability is not considered to be greatly significant in terms of current simplified site classification systems; based on computed Vs30 values, all considered regions can be categorized as NEHRP sites class D (180 < Vs < 360 m/s) or E (Vs < 180 m/s), however, detailed analysis of the shear wave velocity profiles in different subregions of Christchurch show that the expected surficial site response can vary quite a bit across the region despite the relative similarity in Vs30
Under the caption, young people carrying their baggage flutter into the air, away from Canterbury and toward 'Oz'.
In September GNS Earth Sciences reported that after the earthquakes, the Greendale and associated faults were still moving as they settled into a new configuration. At the same time the young were leaving Canterbury (and New Zealand) for a better future in Australia. The population of New Zealand was moving into a new configuration.
Quantity: 1 digital cartoon(s).
Rolleston/Burnham, South Island, NZ
It's been a busy few weeks! Was away on geology fieldtrips all the previous two weeks, then on Saturday morning 4th September 2010 at 4.35 am we got woken in Westport to a reasonable but very long earthquake. My husband was back in Christchurch at the time and texted me saying "are you ok?". I replied, "yes!"...
Canadian-born Mark Quigley is a senior lecturer in Active Tectonics and Geomorphology at the Department of Geological Sciences at the University of Canterbury. He's become an unwitting star as the go-to scientific voice throughout the Canterbury earthquakes, using plain language to help people understand what's behind the earthquake sequence. He's also had his own personal quake story - his Avonside home was badly damaged and is in the red zone.
This paper presents the ongoing development of a new 3D seismic velocity model of Canterbury, New Zealand. The model explicitly represents the Canterbury sedimentary basin, and other significant geologic horizons, which are expected to have important implications on observed ground motions. The model utilizes numerous sources of data, including 3D regional tomography with a variable-depth inferred Moho, seismic reflection survey lines, geotechnical boreholes and well logs, spectral analysis of surface waves, and CPT logs which provide velocity constraints over their respective ranges of application. The model provides P- and S-wave velocity and density (i.e. Vp, Vs and p) over a grid of input points, and is presently being utilized in broadband ground motion simulations of the 2010-2011 Canterbury earthquakes. Comparison of simulated ground motions with those observed in the 2010-2011 Canterbury earthquakes will help provide a better understanding of the salient physical processes which characterized the unique set of strong ground motions recorded in this sequence of earthquake events.
This dissertation addresses a diverse range of topics in the area of physics-based ground motion simulation with particular focus on the Canterbury, New Zealand region. The objectives achieved provide the means to perform hybrid broadband ground motion simulation and subsequently validates the simulation methodology employed. In particu- lar, the following topics are addressed: the development of a 3D seismic velocity model of the Canterbury region for broadband ground motion simulation; the development of a 3D geologic model of the interbedded Quaternary formations to provide insight on observed ground motions; and the investigation of systematic effects through ground motion sim- ulation of small-to-moderate magnitude earthquakes. The paragraphs below outline each contribution in more detail. As a means to perform hybrid broadband ground motion simulation, a 3D model of the geologic structure and associated seismic velocities in the Canterbury region is devel- oped utilising data from depth-converted seismic reflection lines, petroleum and water well logs, cone penetration tests, and implicitly guided by existing contour maps and geologic cross sections in data sparse subregions. The model explicitly characterises five significant and regionally recognisable geologic surfaces that mark the boundaries between geologic units with distinct lithology and age, including the Banks Peninsula volcanics, which are noted to strongly influence seismic wave propagation. The Basement surface represents the base of the Canterbury sedimentary basin, where a large impedance contrast exists re- sulting in basin-generated waves. Seismic velocities for the lithological units between the geologic surfaces are derived from well logs, seismic reflection surveys, root mean square stacking velocities, empirical correlations, and benchmarked against a regional crustal model, thus providing the necessary information for a Canterbury velocity model for use in broadband seismic wave propagation. A 3D high-resolution model of the Quaternary geologic stratigraphic sequence in the Canterbury region is also developed utilising datasets of 527 high-quality water well logs, and 377 near-surface cone penetration test records. The model, developed using geostatistical Kriging, represents the complex interbedded regional Quaternary geology by characterising the boundaries between significant interbedded geologic formations as 3D surfaces including explicit modelling of the formation unconformities resulting from the Banks Peninsula volcanics. The stratigraphic layering present can result in complex wave propagation. The most prevalent trend observed in the surfaces was the downward dip from inland to the eastern coastline as a result of the dominant fluvial depositional environment of the terrestrial gravel formations. The developed model provides a benefi- cial contribution towards developing a comprehensive understanding of recorded ground motions in the region and also providing the necessary information for future site char- acterisation and site response analyses. To highlight the practicality of the model, an example illustrating the role of the model in constraining surface wave analysis-based shear wave velocity profiling is illustrated along with the calculation of transfer functions to quantify the effect of the interbedded geology on wave propagation. Lastly, an investigation of systematic biases in the (Graves and Pitarka, 2010, 2015) ground motion simulation methodology and the specific inputs used for the Canterbury region is presented considering 144 small-to-moderate magnitude earthquakes. In the simulation of these earthquakes, the 3D Canterbury Velocity Model, developed as a part of this dissertation, is used for the low-frequency simulation, and a regional 1D velocity model for the high-frequency simulation. Representative results for individual earthquake sources are first presented to highlight the characteristics of the small-to-moderate mag- nitude earthquake simulations through waveforms, intensity measure scaling with source- to-site distance, and spectral bias of the individual events. Subsequently, a residual de- composition is performed to examine the between- and within-event residuals between observed data, and simulated and empirical predictions. By decomposing the residuals into between- and within-event residuals, the biases in source, path and site effects, and their causes, can be inferred. The residuals are comprehensively examined considering their aggregated characteristics, dependence on predictor variables, spatial distribution, and site-specific effects. The results of the simulation are also benchmarked against empir- ical ground motion models, where their similarities manifest from common components in their prediction. Ultimately, suggestions to improve the predictive capability of the simulations are presented as a result of the analysis.
Two huge wrestlers, one representing 'Port Hills fault' and the other 'Greendale fault' struggle together over a broken Christchurch. Another wrestler, representing 'Other faults' appears in the distance yelling 'Is it my turn yet?' Context - Christchurch has now had three major earthquakes and thousands of aftershocks. It now appears likely that the Christchurch quakes resulted from activity on a fault extending directly eastward from the Alpine fault that remained unknown until last year, says Roger Musson, a seismologist at the British Geological Survey in Edinburgh. The new fault first came to light last September (4th) when a stronger but less calamitous quake shook Darfield, 40 kilometres west of Christchurch. Musson says the latest quake (Feb 22, 2011) probably resulted from an eastward continuation of activity on the same fault. "It has probably not moved for tens of thousands of years, so lots of strain built up," says Musson. The third major quake happened on 13th June 2011. (New Scientist - February 22, 2011)
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This article argues that active coordination of research engagement after disasters has the potential to maximize research opportunities, improve research quality, increase end-user engagement, and manage escalating research activity to mitigate ethical risks posed to impacted populations. The focus is on the coordination of research activity after the 22nd February 2011 Mw6.2 Christchurch earthquake by the then newly-formed national research consortium, the Natural Hazards Research Platform, which included a social science research moratorium during the declared state of national emergency. Decisions defining this organisation’s functional and structural parameters are analyzed to identify lessons concerning the need for systematic approaches to the management of post disaster research, in collaboration with the response effort. Other lessons include the importance of involving an existing, broadly-based research consortium, ensuring that this consortium's coordination role is fully integrated into emergency management structures, and ensuring that all aspects of decision-making processes are transparent and easily accessed.
Surface rupture of the previously unrecognised Greendale Fault extended west-east for ~30 km across alluvial plains west of Christchurch, New Zealand, during the Mw 7.1 Darfield (Canterbury) earthquake of September 2010. Surface rupture displacement was predominantly dextral strike-slip, averaging ~2.5 m, with maxima of ~5 m. Vertical displacement was generally less than 0.75 m. The surface rupture deformation zone ranged in width from ~30 to 300 m, and comprised discrete shears, localised bulges and, primarily, horizontal dextral flexure. About a dozen buildings, mainly single-storey houses and farm sheds, were affected by surface rupture, but none collapsed, largely because most of the buildings were relatively flexible and resilient timber-framed structures and also because deformation was distributed over a relatively wide zone. There were, however, notable differences in the respective performances of the buildings. Houses with only lightly-reinforced concrete slab foundations suffered moderate to severe structural and non-structural damage. Three other buildings performed more favourably: one had a robust concrete slab foundation, another had a shallow-seated pile foundation that isolated ground deformation from the superstructure, and the third had a structural system that enabled the house to tilt and rotate as a rigid body. Roads, power lines, underground pipes, and fences were also deformed by surface fault rupture and suffered damage commensurate with the type of feature, its orientation to the fault, and the amount, sense and width of surface rupture deformation.
On 4 September 2010, a magnitude Mw 7.1 earthquake struck the Canterbury region on the South Island of New Zealand. The epicentre of the earthquake was located in the Darfield area about 40 km west of the city of Christchurch. Extensive damage was inflicted to lifelines and residential houses due to widespread liquefaction and lateral spreading in areas close to major streams, rivers and wetlands throughout Christchurch and Kaiapoi. Unreinforced masonry buildings also suffered extensive damage throughout the region. Despite the severe damage to infrastructure and residential houses, fortunately, no deaths occurred and only two injuries were reported in this earthquake. From an engineering viewpoint, one may argue that the most significant aspects of the 2010 Darfield Earthquake were geotechnical in nature, with liquefaction and lateral spreading being the principal culprits for the inflicted damage. Following the earthquake, an intensive geotechnical reconnaissance was conducted to capture evidence and perishable data from this event. This paper summarizes the observations and preliminary findings from this early reconnaissance work.
The 22 February 2011, Mw6.2 Christchurch earthquake is the most costly earthquake to affect New Zealand, causing an estimated 181 fatalities and severely damaging thousands of residential and commercial buildings. This paper presents a summary of some of the observations made by the NSF-sponsored GEER Team regarding the geotechnical/geologic aspects of this earthquake. The Team focused on documenting the occurrence and severity of liquefaction and lateral spreading, performance of building and bridge foundations, buried pipelines and levees, and significant rockfalls and landslides. Liquefaction was pervasive and caused extensive damage to residential properties, water and wastewater networks, high-rise buildings, and bridges. Entire neighborhoods subsided, resulting in flooding that caused further damage. Additionally, liquefaction and lateral spreading resulted in damage to bridges and to stretches of levees along the Waimakariri and Kaiapoi Rivers. Rockfalls and landslides in the Port Hills damaged several homes and caused several fatalities.
