Far North District's Liquefaction Vulnerability Map: Understand Your Risk
Now Available for Public Access!
We are thrilled to announce the release of the district-wide map outlining the vulnerability of liquefaction in the Far North. This resource is a collaborative effort between the Far North District Council and Vision Consulting Engineers in Kerikeri. It offers property owners, planners, and engineers a clearer understanding of areas potentially susceptible to liquefaction.
Introduction
Welcome to Vision Consulting Engineers' dedicated page for the Far North District's Regional Liquefaction Vulnerability Map. We are excited to provide you with an in-depth understanding of this resource, its implications for our community, and the low earthquake risk we enjoy in the Far North relative to the rest of New Zealand.
What is Liquefaction?
Liquefaction is a phenomenon that occurs during earthquakes when water-saturated soil loses its stability and behaves like a liquid. This can lead to significant damage to buildings and property. However, it's important to emphasize that the Far North is considered a relatively low-risk area for earthquakes compared to other parts of New Zealand. Still, being prepared is crucial.
A Unique Demonstration
Andrew Gee from Christchurch made this video to show friends and family what happened during the 2011 earthquake sequence. Note how the sand appears quite solid at the start of the video, but behaves more like a liquid when shaken.
Far North's Regional Liquefaction Vulnerability Map
This map was prepared using the guidance documents Ministry of Building, Innovation and Employment (MBIE) and Ministry for the Environment (MfE) Planning and engineering guidance for potentially liquefaction-prone land, dated September 2017.
Understanding the Map
Our Liquefaction Vulnerability Map classifies areas into three categories: Unlikely, Undetermined, and Possible
These categories broken down into plain English are:
The Unlikely areas are where it is highly-likely that damage due to liquefaction will be none to minor for a 1 in 500-year shaking event. This does not mean that there will be no damage at the site as there may be damage induced by the shaking itself, such as landslips or falling objects.
The Possible areas are where there is a chance of more than minor damage occurring, due to liquefaction, during a 1 in 500-year shaking event.
The Undetermined areas are ares where there is insufficient information to assess the likelihood of liquefaction occurring based on available information.
Reassuringly, the majority of the Far North region is classified as "Unlikely" when it comes to liquefaction vulnerability. However, some coastal areas are identified as "Possible."
Expert Insights
Ben Perry, the Managing Director at Vision Consulting Engineers, underscores the significance of this initiative, stating, "Knowing an area's likelihood of damage due to liquefaction empowers property owners to take appropriate action, such as reinforcing a building's foundation. It also aids the council and civil defense in land use and emergency planning."
Earthquake Risk in the Far North
A Low Risk Zone
While we acknowledge the potential for liquefaction in certain areas, it's important to emphasize that the Far North District is characterized by a low earthquake risk compared to many other parts of New Zealand. This is backed by rigorous scientific analysis and assessment using New Zealand guidance documents for engineering.
The design earthquake for this assessment is a magnitude 6.5 earthquake with a peak ground acceleration of 0.19g for a subsoil Class C in accordance with Module 1 - Overview of earthquake geotechnical engineering practice guidelines - Version 1 2021.
Explore The Map
We believe that knowledge is the first step toward safety and preparedness. To explore the likelihood of liquefaction-induced damage across the Far North, click the link below to access our Liquefaction Vulnerability Map.
