The awareness of liquefaction has increased markedly since the Christchurch earthquakes. It is basically an earthquake related process of turning a solid soil into a liquid and weaker state. It is most likely to occur in saturated sands and silts.Related to liquefaction is a process called lateral spreading, whereby land moves towards lower areas whilst in a semi liquid state.The Southland areas considered most susceptible to liquefaction include low lying areas of hydraulic fill, peat mires, low lying parts of lake deltas and around the margins of the fjords. The last two magnitude 7+ earthquakes (22 August 2003 and 15 July 2009) resulted in isolated pockets of liquefaction.Reports:Amplified ground shaking and liquefaction susceptibility,Invercargill City - January 2012 (PDF, 2.3MB)Note: The methodology that was used in this report may not hold today after knowledge gained from the Christchurch earthquakes and how that may relate to underlying assumptions regarding Southland. This data was captured at a scale of 1:250,000 (boundaries are indicative).
