Liquefaction vulnerability increase at North New Brighton due to subsidence, sea level rise and reduction in thickness of the non-liquefying layer
The Canterbury Earthquake Sequence (CES) of 2010 – 2011 caused widespread liquefaction related land damage to the city of Christchurch. This paper addresses the impact the CES had on the eastern Christchurch suburb of North New Brighton with emphasis on the ground condition at the time of the initial 4 September 2010 earthquake, as well as subsidence caused by the CES, and the future potential for increased liquefaction vulnerability due to Sea Level Rise (SLR). Subsidence at North New Brighton accumulated throughout the CES due to a reduction in volume of the soil profile through liquefaction; and overall settlement due to regional tectonic subsidence. The total amount of subsidence caused by the CES at North New Brighton was as much as 1 m in some places and this has changed the relationship between the position of the ground surface and the top of the groundwater table. A reduction in thickness of the non-liquefying layer has been shown to increase the vulnerability of the soil profile to liquefaction related land damage during earthquake events. As a coastal suburb, North New Brighton is vulnerable to the impact of SLR and this paper considers the response of the groundwater table to rising sea level and the influence this will have on the thickness of the non-liquefying layer and liquefaction vulnerability.
Russell J, van Ballegooy S, Rogers N and Jacka M (2015). “The effect of subsidence on liquefaction vulnerability following the 2010 – 2011 Canterbury earthquake sequence”. Twelfth Australia-New Zealand Geomechanics Conference, Wellington, Paper 81.
Bradley BA and Hughes M (2012). “Conditional Peak Ground Accelerations in the Canterbury Earthquakes for Conventional Liquefaction Assessment”. Technical Report Prepared for the Department of Building and Housing.
Quilter PW, van Ballegooy S and Russ M (2015). “The effect of sea level rise on liquefaction vulnerability”. Proc. 6th International Conference on Earthquake Geotechnical Engineering, November 1-4, Christchurch, New Zealand.
Hughes MW, Quigley MC, van Ballegooy S, Deam BL, Bradley BA, Hart DE and Measures R (2015). “The sinking city: Earthquakes increase flood hazard in Christchurch, New Zealand”. GSA Today, 25(3-4): doi: 10.1130/GSATG221A.1. DOI: https://doi.org/10.1130/GSATG221A.1
Brown LJ, Beetham RD, Paterson BR and Weeber JH (1995). “Geology of Christchurch, New Zealand”. Environment & Engineering Geoscience, I(4): 427-488.
Russell J, van Ballegooy S, Torvelainen E and Gulley R (2015). “Consideration of ground variability over an Area of geological similarity as part of liquefaction assessment for foundation design”. Proc. 6th International Conference on Earthquake Geotechnical Engineering, November 1-4, Christchurch, New Zealand.
van Ballegooy S, Lacrosse V, Russell J, Simpson J and Malan P (2015). “Comparison of CPT–based simplified liquefaction assessment methodologies based on Canterbury geotechnical dataset”. Proc. Of the 12th Australia New Zealand Conference on Geomechanics (pp. 618-625). Wellington, New Zealand: NZGS & AGS.
Boulanger RW and Idriss IM (2014). “CPT and SPT Based Liquefaction Triggering Procedures”. Report UCD/CGM-14/01, Department of Civil and Environmental Engineering, University of California, Davis CA, 134 pp.
Ishihara K (1985). “Stability of natural deposits during earthquakes”. Proc. of the 11th International Conference on Soil Mechanics and Foundation Engineering, San Francisco, CA, 321-376.
van Ballegooy S, Green R, Lees J, Wentz F and Maurer B (2015). “Assessment of various CPT based liquefaction severity index frameworks relative to the Ishihara (1985) H1–H2 boundary curves”. Soil Dynamics and Earthquake Engineering, Special Issue: Liquefaction in New Zealand and Japan, 79: 347-364.
van Ballegooy S, Malan P, Lacrosse V, Jacka M, Cubrinovski M, Bray JD and Cowan H (2014). “Assessment of liquefaction-induced land damage for residential Christchurch”. Earthquake Spectra, 30(I): 31-55. Doi: 10.1193/031813EQS070M. DOI: https://doi.org/10.1193/031813EQS070M
van Ballegooy S, Cox SC, Thurlow C, Rutter HK, Reynolds T, Harrington G and Smith T (2014). “Median Water Elevation in Christchurch and Surrounding Area after the 4 September 2010 Darfield Earthquake, Version 2”. GNS Science Report 2014/18.
MBIE (2012). “Repairing and Rebuilding Houses Affected by the Canterbury Earthquakes”. Ministry of Business, Innovation and Employment. December 2012
MBIE (2014). “Clarifications and Updates to the Guidance ‘Repairing and Rebuilding Houses Affected by the Canterbury Earthquakes’: Issue 7”. Christchurch, New Zealand: Ministry of Business, Innovation and Employment. October 2014.
van Ballegooy S, Wentz F and Boulanger RW (2015). “Evaluation of a CPT –based liquefaction procedure at a regional scale”. Soil Dynamics and Earthquake Engineering, Special Issue: Liquefaction in New Zealand and Japan, 79: 315-334.
Chang SW, Clement TP, Simpson MJ and Lee KK (2011). “Does sea-level rise have an impact on saltwater intrusion?”. Journal of Advances in Water Resources. 34: 1283-1291, doi: 10.1016/j.advwaters.2011.06.006.
Rogers N, van Ballegooy S, Williams K and Johnson L (2015). “Considering post-disaster damage to residential building construction – Is our modern building construction resilient?”. Proc. 6th International Conference on Earthquake Geotechnical Engineering, November 1-4, Christchurch, New Zealand.