LSN – a new methodology for characterising the effects of liquefaction in terms of relative land damage severity

This paper describes the development of a new depth weighted assessment methodology, which produces a dimensionless number termed the Liquefaction Severity Number (LSN), to assess vulnerability of land to liquefaction-induced damage. This methodology has been developed by comparing measured attributes from the properties damaged by the Canterbury Earthquake sequence, with parameters calculated from approximately 7,500 Cone Penetration Tests (CPT). The results show that the depth to the liquefaction layers (controlled by the groundwater table) is the most important parameter when determining whether liquefaction is likely to cause damage at the ground surface. The paper presents a review of the published literature relating to land vulnerability and the observed effects of strong earthquake shaking in Canterbury, New Zealand. Various liquefaction vulnerability parameters have been calculated and compared with the observed damage attributes. The paper concludes that LSN is an alternative method for characterising vulnerability to liquefaction in residential areas, which provides a better correlation with observed damage than other methods currently available.