March 2001
Report summary
Land use planning for seismic events and building over
active fault lines - key issues regarding the legislation and its implementation by local authorities.
Includes topics such as access to geological information; risk assessment and management; regional
and district planning; the Building Code and integration between the Building Act 1991 and the
Resource Management Act 1991.
Preface
The shape of the New Zealand landscape is strongly influenced by two forces: human endeavour and tectonic plate movement. We have built our towns, cities and homes on land that is constantly subject to fracturing and differential movement as the eastern Pacific Plate grinds against and dives below the Australian plate to the west.
Executive summary
New Zealand is located over an active plate boundary and many parts of the country face a risk of earthquake damage within people's lifetimes. Addressing earthquake events to minimise loss of life and damage to property is a national issue. There is concern about the ability of the Building Act 1991(BA) and the Resource Management Act 1991 (RMA) to adequately manage the use and development of land on or close to fault lines. This was conveyed to the Parliamentary Commissioner for the Environment (PCE) by a Kapiti Coast resident, with extensive experience in earth deformation, who drew attention to the granting of resource and building consents for the development of a local retirement complex sited over an active fault trace and unstable hill slope. Further information from the Earthquake Commission raised difficulties with section 36(2) of the BA, which impacts on insurance coverage for landowners. The New Zealand Geological Society raised concerns about the sufficiency of weight given to scientific evidence in reaching resource consent decisions.
Consultation took place with the agencies and organisations involved, as well as with the individual who raised the matter. Ideas were sought on gaps and possible improvements to the New Zealand system for addressing the use and development of land on or close to fault lines. The resulting report outlines the current statutory regime and the key responsibilities of each of the agencies involved. The relevant work of the Building Industry Authority, the Department of Internal Affairs, the Ministry for the Environment, the Institute of Geological and Nuclear Sciences and the Ministry for Emergency Management is briefly described in so far as it impacts on land development and use over fault lines.
The following issues are discussed:
- access to information on risk, risk assessment and risk management;
- regional and district planning, hazard maps and rules;
- building consents, the Building Code and integration between the Building Act 1991 and the Resource Management Act 1991;
- monitoring, education and guidance under the Building Act 1991; and
- issues in relation to section 36(2) of the Building Act 1991, including the need to educate people about their potential risk before the grant of building consent and before a property is purchased.
Findings & recommendations
Earthquakes are devastating and largely unpredictable events, with low probability but high impact. It is possible to mitigate the most damaging effects of earthquakes by avoiding obviously hazardous sites (such as known active faults) and by good seismic design and construction practice elsewhere.
Experience shows that buildings sited across faults that rupture during an earthquake will typically be more badly damaged than adjacent buildings, and that there is no existing technology that will prevent damage to buildings caused by fault rupture. For this reason it is widely accepted that it is inappropriate to site buildings on or close to active faults.
Research carried out by GNS indicates that despite the fact that most areas of New Zealand are subject to seismic events, few territorial authorities in the regions studied have identified seismic hazard in their district plans and even fewer have rules in their plan for managing earthquakes.
The role of territorial authorities and district planning is pivotal because territorial authorities have responsibility for issuing subdivision and land use consents, as well as responsibility for issuing building consents. Practical guidelines urgently need to be developed to enable territorial authorities to discharge their RMA responsibilities relating to the avoidance or mitigation of earthquake hazards. However, before this can be achieved, ways to incorporate information on seismic hazards and their management into plans and policy statements, and the most appropriate planning options for reducing risk need to be determined.
It is important that:
- Local authorities obtain accurate and relevant scientific information to enable them to assess and manage seismic risk.
- This information is incorporated into the objectives, policies and rules in district and regional plans and policy statements in a consistent manner.
- There is a system whereby territorial authorities and regional councils can regularly update scientific information on seismic hazards.
- The district plan identifies fault lines and areas of seismic hazard and provides for appropriate rules in these areas, with provision for site-specific investigations to be carried out and guidelines for those investigations.
- Territorial authorities do not rely solely on the building consent process to control development on or close to fault lines.
- At all times there is an integrated system for implementing and administering the RMA and BA and the building and resource consent processes.
To address the deficiencies identified in the current system for managing the use and development of land on or close to earthquake fault lines, it is recommended that priority be given to:
The Ministry for the Environment working together with the Institute of Geological & Nuclear Sciences and other interested organisations with structural and geotechnical expertise to develop best practice guidelines for territorial authorities in avoiding or mitigating seismic hazard through the district plan process.
An essential first step will be the identification of barriers to incorporating scientific information into the policies, objectives and rules in plans and policy statements under the Resource Management Act 1991; the investigation and evaluation of planning and other options to reduce risk in different situations depending on seismic hazard type and the level of certainty that exists; and establishing a dialogue with local authorities to increase awareness of seismic problems and potential solutions.
- The Department of Internal Affairs addressing in its current review of the Building Act 1991 the difficulties being experienced with the application of s36(2) of the Building Act 1991; and issues concerning the ongoing monitoring, enforcement, compliance, education and guidance under the Building Act 1991. This will need to be carried out in conjunction with the Building Industry Authority as the primary agency responsible for education and dissemination of information under the Building Act 1991, and for reviewing the operation of territorial authorities in relation to their functions under that Act.
