The Nelson region has the potential to be affected by earthquakes, including the rupture of local fault lines. Council has sought expert advice about improving the accuracy of the mapping of earthquake fault lines that may affect the region, as well as the identification of areas where liquefaction is possible in the event of a major earthquake.
Council currently manages risk from fault hazard through the Nelson Resource Management Plan Fault Hazard Overlay and associated rules.
Rules associated with the current Fault Hazard Overlay aim to reduce the risk to people and property if a fault was to rupture during an earthquake. The focus of the rules is to avoid establishing buildings and other structures directly over an active fault line. This approach will also be applied in the development of the Nelson Plan, our revised resource management plan.
Fault Hazard Overlay in the Nelson Resource Management Plan (NRMP)
The Fault Hazard Overlay was based on the best information available to the Council at the time the Plan was notified in the 1990s. The Overlay contains those known fault traces considered to be active or potentially active. Because most fault traces had not been accurately mapped, a wider area than that which could be affected by any fault rupture was indicated (the mapped areas are generally 150m wide).
A new Fault Hazard Corridor has been developed based on recent updated geotechnical information, which more accurately maps where active fault lines are in Nelson. This Corridor will form the basis of a new Fault Hazard Overlay that will form part of the Nelson Plan. Those purchasing or contemplating development of properties located within the Fault Hazard Corridor should obtain the most up to date information held by the Council regarding the predicted location of fault traces before they start.
The Fault Hazard Corridor report can be downloaded by clicking on the links below.
- Assessment of the location and paleoearthquake history of the Waimea-Flaxmore Fault system in the Nelson-Richmond area with recommendations to mitigate the hazard arising from fault rupture of the ground surface (August 2013)
- Appendix 1 - Maps (34MB PDF)
In 2013, Council consulted with owners of land subject to the Fault Hazard Overlay and Fault Hazard Corridor. Modifications were made to the Fault Hazard Corridor made under the direction of Dr Mike Johnston, following community feedback and subsequent fieldwork during 2013, as shown on the current GIS mapping.
We will update the extent of the Fault Hazard Corridor in mid-2018 using geotech information recently received as part of resource or building consent applications. This will ensure that the Nelson Plan’s Fault Hazard Overlay is up to date as we gain a better understanding of our fault hazard risk in Nelson.
Fault hazard mapping
Council has prepared GIS mapping that shows areas affected by the Fault Hazard Corridor. You can search for fault hazard on a particular property by using our natural hazards map.
Land Information Memorandum (LIM) and Project Information Memorandum (PIM) interim note
In 2013, interim LIM notes were added to property information for those properties found to be subject to the Fault Hazard Corridor. These interim notes were finalised in early 2014 and have now been updated to refer to the Nelson Plan.
Frequently Asked Questions
Why is the Fault Hazard Overlay in the Nelson Resource Management Plan (NRMP)?
The NRMP is used by Council to control the development of land to avoid or reduce the impact of natural hazards, including earthquakes. The Fault Hazard Overlay shown on the NRMP maps, and the associated fault hazard rules, are there to reduce the risk to people and property from ground rupture during an earthquake.
What is the purpose of the Fault Hazard Overlay?
The purpose of the Fault Hazard Overlay is to avoid building construction directly over an active fault line. It acts as a flag to pay extra attention when developing a site or undertaking new building work in that area.
What is the difference between the Fault Hazard Overlay and the new Fault Hazard Corridor?
Since the Fault Hazard Overlay was prepared in the 1990s, a considerable amount of new information has become available. When property owners provide geotechnical information as part of consent applications to build or extend buildings within the Fault Hazard Overlay, this information is collated by Council and contributes to a more exact knowledge of the location of fault lines.
This information, combined with other geotechnical investigations, has contributed to a report prepared by GNS Science to provide more accurate information about the location of fault lines in Nelson.
The new information has been added to Council’s GIS maps as a Fault Hazard Corridor, but the existing Fault Hazard Overlay in the NRMP has not changed yet.
What is GNS science?
GNS Science is a New Zealand Crown Research Institute. It is owned by the Government and carries out research for the benefit of New Zealand. GNS science operates the national geological hazards monitoring network, and is also contracted by councils to provide scientific advice and information.
Is a property at greater risk during an earthquake if it is within the Fault Hazard Overlay/Corridor?
Ground rupture along a fault line is different from the general shaking that could occur throughout Nelson during an earthquake, although both can cause damage. The ground rupture effect is confined to fault lines. Fault rupture movements can cause significant damage to structures built directly across a fault line.
If only part of the property is affected, what does this mean for the rest of it?
Building on parts of the property which are not within the Fault Hazard Overlay/Corridor is not affected by the Fault Hazard Overlay rules.
How will people know about the fault hazard information?
The Council has an obligation to make fault hazard information available to the public, under the Local Government Official Information and Meetings Act 1987 and the Building Act 2004.
That means people can access information held by the Council about their property, and about any property they are considering buying. The Council has placed notes on relevant land and property information files to inform potential buyers about the fault hazard information.
My house is not included within the Fault Hazard Corridor, only a small area of my property. Why is there still a note on my property file?
Even in circumstances where the fault hazard is only identified on a small portion of a property (e.g. driveway, garden, farm paddocks), Council is still required to note this on the relevant land and property information files. A Land Information Memorandum (LIM) report contains a map which will show where on the property the fault hazard is located.
Where do I find information about what to do following an earthquake?
Civil defence information and advice on getting prepared can be found on the Nelson Tasman Civil Defence Emergency Management website.
How do I provide feedback to Council about the Fault Hazard Corridor?
At this time, we are not seeking further feedback from the community. We will update the extent of the Fault Hazard Corridor in mid-2018 using geotech information recently received as part of resource or building consent applications and will communicate this work with landowners at that time.
The fault hazard information will be used to inform the Nelson Plan. When the Draft Nelson Plan is released for public consultation this will be the community’s opportunity to provide feedback on the draft natural hazards provisions, prior to notification of a Proposed Nelson Plan. We will let the community know how to get involved in providing feedback on the Draft Nelson Plan closer to public release.