New data improves liquefaction maps
1 December 2017
Liquefaction risk maps for Hawke’s Bay have been updated by Hawke’s Bay Regional Council, based on the latest scientific testing by GNS Science.
The reassessment report, released this week, builds on and updates the 1999 GNS liquefaction study in Hawke’s Bay. The report is based on a range of scientific factors including geology and soil data, ground water data, and around 800 CPT (Cone Penetrometer Test) ground tests. While not as extensive as the 10,000 tests carried out in Christchurch, these still provide useful information.
According to the report there is some change in areas of Hastings. As further testing further refines ground conditions, updates will continue to be made to the maps. For the new more detailed and refined information see: www.hbemergency.govt.nz/hazards/portal and click on the ‘Earthquake Liquefaction’ link.
To address the potential for liquefaction, Hastings District Council has updated its guidelines in consultation with local and national geotech firms. For the guidelines see: www.hastingsdc.govt.nz/services/building-consents-information/building-consents
The changes include setting minimum standards for ground testing, depending on the zone the land is in.
Hastings District Council planning and regulatory services manager John O’Shaughnessy said the changes “will build in better resilience into our housing stock over time”.
“This updated information will help identify areas that require different levels of testing of ground conditions to help us make good decisions around development, and building resilience into our infrastructure.”
Hastings District Council will be holding a forum with the land development industry to discuss the implications of the new liquefaction maps.
Liquefaction can occur when a large earthquake shakes up water-logged silty ground. For a detailed description of liquefaction see: www.hbemergency.govt.nz/hazards/earthquake.
1 December 2017