Mapping of fault rupture avoidance zone in Westland
Mapping of fault rupture hazard risk in Westland.
Westland District Council has received two reports into Fault Rupture Hazard Risk in Westland commissioned by the West Coast Regional Council from the Institute of Geological and Nuclear Sciences Ltd (GNS).
The first report mapped the Alpine Fault within the West Coast Region and suggested “Fault Rupture Avoidance Zones” be created around the fault. Specific reference was given to the Styx – Toaroha area and Franz Josef/ Waiau. This report was received by Westland District Council in October 2010. All property owners within these suggested zones have been advised by Council of the existence of this report. You can view the report here.
A second report was subsequently commissioned from GNS to produce more accurate data around Fault Rupture Risk in Franz Josef / Waiau and to make suggestions on how the West Coast Regional Council and Westland District Council should respond to this information. This study utilised LiDAR imagery and RTK-GPS mapping to define the Alpine Fault in greater detail in the Franz Josef/Waiau area. The mapped “Fault Rupture Avoidance Zone” is now slightly narrower as the fault information has greater certainty. The suggested area of land that will be most affected by fault rupture is 130 metres in width within Franz Josef / Waiau. You can view this report here.
GNS states that the likelihood of an earthquake event occurring along the Alpine Fault is 20% within the next 30 years. The Average Recurrence Interval of surface rupture of the Alpine Fault is 1 in 333 years. The predicted movement during fault rupture is predicted to be 8-9 metres horizontally, and 1-2 metres vertically.
Dr Rob Langridge of the Institute of Geological and Nuclear Sciences gave a presentation on the two above reports and the Alpine Fault in general in Franz Josef on the 29th February 2012. A copy of his presentation is available here. Please note that this is a 4MB file and may take some time to download.
What will happen now?
Council has contacted affected landowners to inform them of this new information.
A meeting will be held in Franz Josef /Waiau to discuss the reports on Wednesday the 29th February 2012 at the Department of Conservation Visitor Centre commencing at 7pm.
Land Information Memorandum
Westland District Council is required to pass on information that it holds on hazards onto any person that applies for a Land Information Memorandum (LIM) in the future so people will be advised if the subject property is located within the Fault Rupture Hazard Area.
Building Consent Applications
When assessing applications for Building Consents, the Westland District Council is required to safeguard people from injury caused by failure of a structure and loss of amenity due to behaviour of the building. For this reason, buildings with an importance category of over 1 will not be able to comply with the Building Code.
Under the current Building Code, existing commercial development will only be required to be fully upgraded to comply with the Building Code provisions for the portion of the building subject to the building consent application (excluding fire and accessibility requirements). Any change of use that is increasing the scale of use or application to extend the life of a building will be required to comply with the Code and will therefore be difficult for Council to approve. It is important to note that any Commercial building will also be subject to the provisions of any Earthquake Prone Building Policy. Dwellings will not be subject to the Earthquake Prone building policy, and any extensions to non-habitable parts of the building (carports, decks etc) will not be required to comply with the code, if they require building consent at all. Alterations to habitable parts of a dwelling will be unable to be approved.
Changes to the District Plan
The Planning Department have drafted a Plan Change for consideration by the Strategy Committee. A copy of these draft changes have been sent to those landowners within the areas suggested to be subject to fault rupture hazard. A copy of the draft proposed changes and the information sheet accompanying these changes is available here.
Maps have been generated indicating the draft Franz Josef/ Waiau Fault Rupture Avoidance Zone. These are available here.
Council is currently seeking comment on these draft proposed changes. These comments should be provided in writing and either posted to Rebecca Strang, District Planner at Westland District Council, Private Bag 704, Hokitika 7842 or emailed to Rebecca Strang.
Please provide comments by Friday the 30th March 2012.
The Westland District Council Strategy Committee will then consider the comments. Any proposed plan change that the Strategy Committee then decides to notify will be subject to a formal submission period.
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If you would like to discuss this further, please contact Richard Simpson or Rebecca Strang
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Copyright © Westland District Council 2012