Coupling ground motion simulation with regional modelling for rapid impact assessment

QuakeCoRE undertakes ground motion simulations as part of its computational workflow. Impact assessment is one of the subsequent downstream outcomes, and allows QuakeCoRE to assess estimated impacts for earthquakes – both recent ruptures and potential future earthquake scenarios. When coupled with near-real-time (NRT) ground motion modelling, these tools also provide NRT assessment. Following this, the susceptibility of a location or region to the earthquake-induced geotechnical and geologic hazards can be assessed. The three impact assessment types are currently considered: macro impact (via PAGER), liquefaction and landside. In this poster attention is given to the first two of these models which have been operationalised, while landslide model implementation is currently on going

Geologic and geomorphic influence on the spatial extent of lateral spreading in Christchurch, New Zealand

Liquefaction-induced lateral spreading during earthquakes poses a significant hazard to the built environment, as observed in Christchurch during the 2010 to 2011 Canterbury Earthquake Sequence (CES). It is critical that geotechnical earthquake engineers are able to adequately predict both the spatial extent of lateral spreads and magnitudes of associated ground movements for design purposes. Published empirical and semi-empirical models for predicting lateral spread displacements have been shown to vary by a factor of <0.5 to >2 from those measured in parts of Christchurch during CES. Comprehensive post- CES lateral spreading studies have clearly indicated that the spatial distribution of the horizontal displacements and extent of lateral spreading along the Avon River in eastern Christchurch were strongly influenced by geologic, stratigraphic and topographic features

Comparisons between deterministic and probabilistic liquefaction assessment approaches

Liquefaction assessments are commonly undertaken by geotechnical engineers using a deterministic approach. This approach does not appropriately take into account the significant uncertainties associated with a liquefaction assessment and can potentially compound the conservatism that is introduced when selecting input parameters. Therefore, the deterministic assessment approach can be conservative and the expected performance poorly understood. This research project looks at an alternative approach for liquefaction assessments – a probabilistic assessment. Other researchers have hypothetically experimented with the idea, but have never operationalised a probabilistic approach

Geologic expressions of contemporary and paleo-liquefaction: Insights into strong ground motion and site characteristics

Recurrent liquefaction in Christchurch during the 2010-2011 Canterbury earthquake sequence created a wealth of shallow subsurface intrusions with geometries and orientations governed by (1) strong ground motion severity and duration, and (2) intrinsic site characteristics including liquefaction susceptibility, lateral spreading severity, geomorphic setting, host sediment heterogeneity, and anthropogenic soil modifications. We present a suite of case studies that demonstrate how each of these characteristics influenced the geologic expressions of contemporary liquefaction in the shallow subsurface. We compare contemporary features with paleo-features to show how geologic investigations of recurrent liquefaction can provide novel insights into the shaking characteristics of modern and paleo-earthquakes, the influence of geomorphology on liquefaction vulnerability, and the possible controls of anthropogenic activity on the geologic record. We conclude that (a) sites of paleo-liquefaction in the last 1000-2000 years corresponded with most severe liquefaction during the Canterbury earthquake sequence, (b) less vulnerable sites that only liquefied in the strongest and most proximal contemporary earthquakes are unlikely to have liquefied in the last 1000-2000 years or more, (c) proximal strong earthquakes with large vertical accelerations favoured sill formation at some locations, (d) contemporary liquefaction was more severe than paleoliquefaction at all study sites, and (e) stratigraphic records of successive dike formation were more complete at sites with severe lateral spreading, (f) anthropogenic fill suppressed surface liquefaction features and altered subsurface liquefaction architecture

Evaluation of Liquefaction Potential of Pumiceous Deposits Through Field Testing

Pumice materials are frequently encountered in many engineering projects in New Zealand. Because of their lightweight, highly crushable and compressible nature, they are problematic from an engineering and construction viewpoint. However, there is very little information on the liquefaction characteristics of pumice deposits and most empirical procedures available for evaluating the liquefaction potential of sands are derived from hard-grained (quartz) sands

Earthquake response of underground pipeline networks in Christchurch, NZ

This paper explores key aspects of underground pipeline network response to the Canterbury earthquake sequence in Christchurch, New Zealand, including the response of the water and wastewater distribution systems to the MW6.2 22 February 2011 and MW6.0 13 June 2011 earthquakes, and the response of the gas distribution system to the MW7.1 4 September 2010 earthquake, as well as the 22 February and 13 June events. Repair rates, expressed as repairs/km, for different types of pipelines are evaluated relative to (1) the spatial distribution of peak ground velocity outside liquefaction areas and (2) the differential ground surface settlement and lateral ground strain within areas affected by liquefaction, calculated from high-resolution LiDAR survey data acquired before and after each main seismic event. The excellent performance of the gas distribution network is the result of highly ductile polyethylene pipelines. Lessons learned regarding the earthquake performance of underground lifeline systems are summarized. © 2014, Earthquake Engineering Research Institute

pipeline damage assessment

Recent earthquakes show that pipeline damage is severe in the areas where permanent ground deformations (e.g., liquefaction zones) occur. Ground movement hazard to pipeline systems can be assessed by using ground displacement measurements around the location of pipelines. There are many different ways of measuring ground displacements after an earthquake occur. This paper compares displacements measured in Avonside area, Christchurch, NZ, by using four different ways with respect to their effects on pipeline damage assessments. They are air photo, satellite, high resolution light detection and ranging (LiDAR) surveys data presented at 4- and 56-m grids acquired before and after the M(w)6.2 22 February 2011 earthquake. Avonside area was in the liquefaction zones of the 22 February 2011 earthquake. Where possible, benchmark measurements were also included in the comparisons. In this study, the focus was on asbestos cement and cast iron water pipelines as the length of the pipelines and the number of damages in the study area was much higher compared to other pipe materials, providing sufficient repair rate data passing the screening criteria to develop linear regressions. The correlations between pipeline damage and lateral ground strains were developed by calculating the horizontal strains from these four different type displacements. The comparisons show that satellite imagery is good for estimating total movements but not so good for estimating lateral strains and conversely LiDAR surveys are not so good for estimating total movements, but much better for estimating lateral strains. Hence, pipeline damage correlations with LiDAR calculated strains provide higher determination coefficient (r(2)) value. The results of comparisons are presented and discussed