Management of natural hazard risks, such as liquefaction, has been a grey area for New Zealand’s residential land development sector. The “February 2011 Christchurch Earthquake” – second most populated city in New Zealand- was one such event.
The earthquake paired with significant liquefaction saw over 400,000tonnes of silt brought up affecting over 600,000 homes and costing over NZD$40billion in damages, making it New Zealand’s costliest natural disaster at the time. Our engineering community were well aware it could happen but the risk was not perceived to be significant enough for residential dwellings.
Hence, in 2021, just over ten years following the Canterbury earthquake, the regulations governing how residential structures are designed changed.
The Auckland Council responded by publishing liquefaction hazard maps and implementing the new rules at the building consent stage of new residential developments.
This paper discusses the process set up including hazard maps and standard foundation designs, and presents the challenges and outcomes in implementing the change.