The Nelson region contains a number of faults, eight of which are identified as active or potentially active. These are the Flaxmore, Waimea, Eighty-Eight, Jenkins, Whangamoa, Bishopdale, Grampian and Hira faults. Therefore, much of Nelson has the potential to be affected by earthquakes. Earthquakes may result in the rupture or deformation of land surrounding these faults.
Our understanding of fault hazard in Nelson continues to evolve as new areas are investigated and we undertake more detailed studies of known faults. Methodologies for assessing fault hazard have also changed over time especially in response to recent earthquakes, such as the 2010-2011 Christchurch and 2016 Kaikoura earthquakes. The studies commissioned by Nelson City Council since the 1990s are described below.
Fault hazard assessments and mapping in Nelson
Fault Hazard Overlay in the Nelson Resource Management Plan (NRMP)
The Fault Hazard Overlay in the NRMP was based on the best information available to the Council at the time the Plan was notified in the 1990s. The overlay contains known faults considered to be active or potentially active. The faults are surrounded by a wider area than would be expected to be affected by any fault rupture due to uncertainty of the faults’ location (the mapped areas are generally 150m wide).
Rules in the NRMP associated with the existing 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.
A new Fault Hazard Corridor was identified in 2013 which more accurately mapped the location of active faults in Nelson based on updated geotechnical information. The Council consulted with owners of land within the NRMP Fault Hazard Overlay and the Fault Hazard Corridor. Modifications were made to the Fault Hazard Corridor under the direction of Dr Mike Johnston. The ‘corridor’ refined the NRMP overlay from 150m wide, reducing the width in areas where there was more certainty about the location of the fault, hence the renaming from ‘overlay’ to ‘corridor’.
The Fault Hazard Corridor report can be downloaded here:
- 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
The Fault Hazard Corridor was updated again in 2019 using geotechnical information received as part of resource or building consent applications. Links to this report are below.
- Natural Hazards fault hazard fault rupture update - Mike Johnston - May 2019 (922KB PDF)
- Natural Hazards fault rupture update mapping - Mike Johnston - May 2019 (900KB PDF)
- Nelson Plan Natural Hazards Fault Rupture amended mapping - Mike Johnston - May 2019 (9.8MB PDF)
As part of the ongoing process to update fault hazard information and to inform future resource management plans, a revised assessment of faults in Nelson was completed in 2021. This is the most up to date information we have on faults in the Nelson region.
This report identifies the areas around the active or potentially active faults in the region that could potentially deform or rupture the ground surface and are shown as a ‘fault deformation overlay’. The overlay comprises:
- ‘Existing section of fault rupture overlay’ (i.e. areas that remain unchanged from the 2019 revision).
- ‘Revised section of existing fault rupture corridor’ (i.e. areas revised since the 2019 revision).
- ‘Less defined section of the overlay’ (i.e. where the location of the fault trace is less certain).
The overlay has been developed in general accordance with national guidance produced by the Ministry for the Environment (MfE) in 2003. The MfE guidance Planning for Development of Land on or Close to Active Faults can be found here.
The 2021 report can be downloaded here:
To see mapping associated with this report please view the latest map:
Please note that the data contained within the Revised Nelson Fault Deformation Overlay report has been generated at a regional scale. Therefore, the maps are indicative of areas where faults could potentially deform or rupture the ground surface within an individual site or property. To assess the specific fault hazard at any individual site or property, a site-specific assessment may need to be undertaken.
How do I know if my property is located within an area potentially susceptible to fault hazard?
Use the link above to the natural hazards webmap to find out whether the latest information we hold indicates that your property may be susceptible to fault hazard.
What if my property is within an area potentially susceptible to fault hazard?
Council is required to update Land Information Memoranda (LIMs) notations with new and updated information relating to natural hazards, including fault hazard.
Fault hazard information may be used in building, subdivision or resource consent processes.
In the future, areas of Nelson that may be susceptible to faults are expected to be included into the NRMP, or into a new resource management plan.
Frequently Asked Questions (click here for FAQs relating to fault lines and hazard in the Nelson region)