Projects

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.

1.

Planning and Policy

(a) National Policy Statement on Urban Development 2020 evidence base

Gunnell and Beban, 2021 explored the evidential standard for natural hazards being utilised as a qualifying matter to reduce intensification requirements under the NPS-UD. The quantitative data require to support such a reduction is a key component to ensuring the effective management of natural hazards can be achieved under the NPS-UD. Utilising RiskScape 2.0 we are seeking develop a quantitative natural hazard risk evidence base to inform future development direction.

(b) Active Fault Guidelines case study

Gunnell and Beban, 2021 explored the evidential standard for natural hazards being utilised as a qualifying matter to reduce intensification requirements under the NPS-UD. The quantitative data require to support such a reduction is a key component to ensuring the effective management of natural hazards can be achieved under the NPS-UD. Utilising RiskScape 2.0 we are seeking develop a quantitative natural hazard risk evidence base to inform future development direction.

(c) SLIDE PROGRAMME DISSEMINATION

The SLIDE research programme sought to provide improved knowledge about the behaviour of slopes in response to earthquake shaking and rain events, and focused on the hill slopes around Wellington City. Outputs from the SLIDE research programme address vulnerability of dwellings to landslides, infrastructure models for analysing impacts, landslide run out models, quantitative landslide risk analyses, and remediation approaches for modified slopes, all of which is relevant to planning and policy practitioners.

(D) Science to Practice Workshops

A core part of the Planning and Policy project, and it’s predecessors, are the Science to Practice Workshops. These workshops have previously been hosted at GNS Science, and are primarily attended by planners and emergency management practitioners from across the Wellington Region. We share the latest natural hazard and risk science with attendees, and complement this with the guidance on implementing this science in planning frameworks. The workshops also include applied exercises such as undertaking master planning for Petone (derived from Hutt City District Plan Change 29) and risk tolerability exercises that are repeatable within our communities.

In 2020/21, we engaged directly with the Masterton, Carterton and South Wairarapa Councils, developing a workshop tailored to the natural hazards and risk most relevant to them. This workshop focused on liquefaction and active faulting hazards, and the relevant guidance for is one we look forward to rolling out for other Councils in the future, achieving maximum value, of the most relevance, and in the most efficient manner for participants.

Under the Science to Practice Workshop series, the It’s Our Fault programme is also able to deliver workshops on engaging with our communities on natural hazard and risk, including risk tolerability, and on the full suite of natural hazards and risk researched in the programme and at GNS Science.

project co-leads:
Sarah Gunnell, Saskia de Vilders, Scott Kelly and James Beban

2.

Risk and Loss Modelling: Fire Following Earthquake

Through three years of work on modelling fire following earthquake (FFE) for Wellington City under IT’S OUR FAULT, we have built on previous work undertaken over a decade ago by developing new methodologies, incorporating the greater availability of data and insights from global literature. We have now modelled impact and loss for multiple earthquake scenarios, generating a large amount of data that may be used for various purposes, including assessing the impact of mitigation strategies. The outputs produced to date provide a good overview of the location and range of impacts that may be experienced in earthquake events affecting Wellington. A simple method for evaluating the effect of ignition suppression has been developed, accounting for suppression by residents, firefighting capacity across time, access disruption and mains water availability.

To meet the needs of key stakeholders (including Wellington Region Emergency Management Office, Fire and Emergency NZ, Wellington Lifelines Group and Wellington Water), we are now undertaking further work on investigating potential suppression and risk mitigation options. Existing ignition and fire spread data will be used to better identify areas to target with residential site visits. 

Through an initial workshop in the first quarter, mitigation strategies of interest to stakeholders will be discussed which will guide further research.

A literature review of mitigation options will be undertaken to better understand strategies employed internationally, and how they may be modelled in future work. Potential examples include assessing improved firefighting capacity and placement of reservoirs for firefighting.

These efforts will support the evidence base required for externally-led projects, including communicating FFE risk to the community and supporting the proposed business case for FFE risk reduction.

project lead:
Finn Scheele

3.

Tsunami Hazard and Vulnerability

In the past few years, IT’S OUR FAULT tsunami tasks have focused on identifying and quantifying the challenges associated with evacuation in the event of local-source tsunami, i.e., those generated on nearby faults with short travel times to the Greater Wellington region. The investigations included the identification of local fault sources posing tsunami hazards, estimate of tsunami travel times from the identified local fault sources, and evacuation time modelling using the Least-Cost approach.

The Least-Cost approach used in the evacuation modelling provides overall estimates of evacuation times required for at-risk occupants to reach outside tsunami evacuation zones. However, this approach is unable to identify bottlenecks of evacuation routes, and no infrastructure damage was assumed in the modelling.

In 2021-2022, we will extend our agent-based evacuation modelling of the Wellington CBD and southern suburbs to Porirua and the Kāpiti Coast. This will identify potential bottlenecks in tsunami evacuation and inform improvements to evacuation planning.

project co-leadS:
Xiaoming Wang and William Power

4.

Subduction Zone Hazard

Finding evidence for past subduction earthquakes in the Wellington Region is continuing to be challenging. However, it is vitally important for ground-truthing and providing magnitude and recurrence interval constraints on the forecasted rupture of the currently locked patch of the Hikurangi subduction interface beneath the Region. The past few years of IT’S OUR FAULT (IOF) subduction earthquake research have focused on a transect of sites perpendicular to the subduction zone, including at Cape Palliser in the Wairarapa and in the north-eastern South Island.

Holocene marine terraces on the southeast Wairarapa coast are interpreted to record uplift from upper plate fault (Palliser-Kaiwhata Fault) earthquakes. In early 2021 we excavated pits on marine terraces that were uplifted in past earthquakes to constrain the age of uplift. Work is ongoing to compare the age of uplift at Cape Palliser with the timing of subduction earthquakes inferred from subsidence at sites in the north-eastern South Island. Meanwhile, we are working to extend our records of past uplift of the Wairarapa Coast and subsidence at Mataora-Wairau Lagoon and Kāpara-te-hau Lake Grasssmere in Marlborough, to understand more about past subduction earthquakes beneath Cook Strait. We hope to undertake preliminary investigations at sites in both the Wairarapa and Marlborough in 2022.

To allow integration with research in other areas, we also plan to create physics-based models of deformation in plausible subduction interface earthquakes. These models will allow estimation of seafloor deformation(necessary for tsunami models) and ground shaking for a range of possible future earthquakes.

project lead:
Andy Howell

5.

Northern Ōhāriu Fault Slip Rate and Recurrence Interval

The Northern Ōhāriu Fault is one of the major active strike slip faults of the lower North Island. It extends for over 60 km through the Kāpiti Coast District and into Horowhenua and is thought to be the northern extension of the Ōhāriu Fault. Understanding seismic hazard along the Northern Ōhāriu Fault is becoming increasingly important as the Kāpiti Coast and Horowhenua districts are two of the fastest growing regions in the southern North Island with rapid population growth and expansion of housing. In addition to this, they are locations of major infrastructural development with plans for expressways along the Wellington-Levin corridor.

This task will involve measuring and dating earthquake offset along the Northern Ōhāriu Fault, as well as excavating a trench across the fault to provide a window into its seismic history. Slip rate, recurrence intervals, and earthquake displacement on the Northern Ōhāriu Fault will be revaluated and its link to the Ōhāriu Fault will be explored. By doing this, we hope to gain a better understanding of how the Northern Ōhāriu and Ōhāriu Faults fit into the seismic hazard of the lower North Island, facilitating the implementation of better-informed seismic hazard mitigation strategies in a rapidly growing region.

project co-leadS:
Genevieve Coffey and Russ Van Dissen