Back in 2006, IT’S OUR FAULT supported Wellington to become a more resilient city through a comprehensive study of the likelihood of large Wellington earthquakes, their effects and impacts on humans and the built environment.
Today, the programme is supporting the region's growing resilience with targeted science and policy research projects in line with community and local government needs.
While the activity and hazard posed by the first order faults (Wairarapa, Wellington, Ōhāriu) in the Wellington Region is quite well known, there is much less known about second order faults. Mapping using lidar data has identified several “new” second order active faults near population centres in the Wairarapa similar to the Mastertonand Carterton faults. Paleoearthquake records for all of these second orderfaults are relatively poor, limiting our ability to robustly forecast the earthquake hazard.
Two paleoseismic trenches were excavated during FY25-26, one across the Masterton Fault and one across the recently-discovered Papawai Fault. Trenches were documented and samples were collected for radiocarbon and luminescence dating.
Preliminary analyses of trench data are underway and will be continued into FY26-27. This includes digitisation of trench logs, interpretation of trench data to investigate evidence of past earthquakes, development of age models using radiocarbon and luminescence ages, and final synthesis of data to develop earthquake records for each fault. These records will be compared with those from other faults in the lower North Island (e.g. the Wairarapa Fault) and the Hikurangi Subduction Zone, to examine the potential for multi-fault rupture orother fault interactions.
Results of this work will feed into and improve datasets that inform the National Seismic Hazard Model including the Community Fault Model, Paleoseismic Site Database, and New Zealand Active Faults database.
Recent research has revealed the potential for MW 8-9 earthquakes on the southern Hikurangi Subduction interface that can produce severe ground shakingand tsunami inundation. Despite widespread recognition of this hazard source for the Wellington Region, limited modelling of the impacts of Hikurangi earthquake scenarios has been undertaken.
This project will extend and improve the impact modelling workflows established in FY25-26 for the AF8+ scenarios, additionally considering tsunami impacts alongside ground shaking. Scenarios will be scoped and selected to alignthe earthquake and tsunami source, and other hazards such as landslides and liquefaction will be considered, depending on data availability. Modelling will include building damage, human casualties and household impacts, as well as infrastructure impact modelling undertaken by University of Canterbury.
The suite of modelling outputs will be suitable for a range of decision-making purposes, including emergency management, land use planning and insurance claims estimation.
Under the incoming resource management legislation Councils are required to develop spatial plans, and this project aims to assist with this process for the Wellington Region.
Agap analysis will be undertaken of the existing Greater Wellington Regional Spatial Plan and the requirements under the Natural Environment Bill. Astocktake of data available to fulfil the natural hazard requirements ofregional spatial planning currently available through the IOF programme, andavailable through national models will be completed. This will include an assessment if they are fit for purpose and if not, what would be required tomake them so.
The gap analysis and stocktake will be undertaken in a collaborative workshop and the results, including how a regional spatial plan could cascade to regulatory plans, and data requirements and availability, will be workshopped with the District Councils. The project will be undertaken in conjunction with Urban Edge Planning.
A range of activities will be undertaken to disseminate It’s Our Fault programme knowledge, outputs and datasets as widely as possible.
This will include working alongside the Planning and Policy project to add a summary of earthquake resilience datasets and research to the website to help make data more accessible. This may include links to hazard maps ordatasets available outside of the It’s Our Fault programme.
We will also continue to deliver public outreach talks and fieldtrips, continue engagements with mana whenua and participate in hui and wānanga, for example with the Joint Centre for Disaster Research Centre colleagues for the NgāNgaru Wakapuke Endeavour research programme.