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Purpose of the Report 

To identify and map active faults in Upper Hutt City and assess their potential hazard for land use planning. 

Geographic Area Covered 

Upper Hutt City, including urban, semi-rural and rural areas traversed by the Wellington, Akatarawa, Otaki Forks, Moonshine, and Whitemans Valley faults. 

Summary of Key Findings 

This report presents the results of a fault trace survey conducted in Upper Hutt City to identify active faults and assess their potential hazard for land use planning. The study was commissioned by Greater Wellington Regional Council and Upper Hutt City Council and carried out by the Institute of Geological & Nuclear Sciences. It follows the Ministry for the Environment’s guidelines for managing development near active faults, using a risk-based approach that considers fault location, recurrence interval, and building importance. 
 
Five active faults were identified: Wellington, Akatarawa, Otaki Forks, Moonshine, and Whitemans Valley. The Wellington Fault is the most active, with an estimated recurrence interval of 650 years and capable of producing magnitude 7.5 earthquakes. It is classified as Recurrence Interval Class I. The Akatarawa and Otaki Forks faults are less active, with estimated recurrence intervals placing them in Class III. The Moonshine Fault is tentatively placed in Class IV, and the Whitemans Valley Fault in Class V. 
 
Fault Avoidance Zones were mapped around each fault based on the complexity and certainty of their surface traces. These zones range from well-defined to poorly constrained, with widths varying from 40 to over 300 meters. The zones are intended to guide land use planning and development decisions, especially for buildings with higher importance categories. 
 
The report recommends further geological investigations to better constrain fault locations and recurrence intervals, particularly for faults with low confidence classifications. It also suggests updating planning policies to reflect the new fault data and ensure consistent hazard mitigation across the region. The findings support a proactive approach to managing fault rupture hazards and protecting life and property in Upper Hutt City.