More targeted approach to earthquake-prone buildingsBuilding and Housing
The Government is revising its policy on managing earthquake risk by better targeting regulations on buildings where location, use and type pose the greatest risk to life, Building and Housing Minister Dr Nick Smith said in a speech today to the Mainland regional conference of the National Party in Ashburton.
“The priority in developing this earthquake strengthening policy for buildings is public safety and minimising future fatalities. We also need to ensure the response is proportionate to the risk, that the costs are minimised and that we retain as much of our built heritage as possible,” Dr Smith says.
The four significant changes to the policy are:
- Varying the timetable for strengthening relative to earthquake risk
- Prioritising education and emergency buildings for strengthening
- Reducing the number of buildings requiring assessment; and
- Introducing new measures to encourage earlier upgrades.
“The timeframe for identification and assessment of five years and strengthening of 15 years is to be varied relative to seismic risk. The return period for a significant earthquake (MM8) ranges from 120 years in Wellington, to 720 years in Christchurch, to 1700 years in Dunedin, and only once every 7400 years in Auckland. New Zealand is to be categorised into low, medium and high seismic risk zones with timeframes for assessment of five, 10 and 15 years and strengthening of 15, 25 and 35 years,” Dr Smith says.
“Education and emergency buildings will be targeted by requiring that in high and medium seismic risk areas they be identified and strengthened in half the standard time. We are prioritising all education buildings regularly occupied by 20 people or more. We also want to ensure buildings like hospitals can maintain services in the aftermath of a significant earthquake.
“The scope of buildings requiring assessment is to be reduced from an estimated 500,000 to 30,000. We are excluding farm buildings, retaining walls, fences, monuments, wharves, bridges, tunnels and storage tanks. The new methodology for identifying earthquake-prone buildings will ensure the focus is on older buildings like unreinforced masonry that pose the greatest risk.
“Building owners are to be encouraged to upgrade their buildings ahead of the allowable timeframe by establishing a web based public register and requiring notices on such buildings highlighting the level of risk. There will also be a new requirement to strengthen earthquake-prone buildings when doing substantial alterations.”
The Government also confirmed that the earthquake-prone building definition as being less than 34 per cent of the new building standard (NBS), a 10-year extension for listed heritage buildings, and exemptions from strengthening for low risk, low occupancy buildings, would remain in the policy.
“The effect of these policy changes is that buildings like schools, universities and hospitals in high and medium seismic risk areas will have to be upgraded more quickly, but buildings in low risk areas like Auckland and Dunedin more gradually. This more targeted approach reduces the estimated cost from $1360 million to $777 million while retaining the safety gains. The policy will result in an estimated 330 fewer deaths and 360 fewer serious injuries from earthquakes over the next century,” Dr Smith says.
“The select committee is considering the Bill and will be reporting back to Parliament in July with passage later this year. We will also be consulting on the detailed regulations like the assessment methodology, the Earthquake-Prone Buildings Register, the building notice requirements and the definition of substantial alterations.
“There are no easy answers to the seismic risk posed by thousands of older buildings in New Zealand. We cannot completely eliminate the risk to life, nor save every heritage building, nor avoid a bill for hundreds of millions in upgrading. This is the most comprehensive policy of any seismically active country for dealing with older buildings and strikes the right balance between safety, cost, heritage and practicality.”
MM8 refers to the Modified Mercalli Intensity Scale. A MM8 is the most frequent of damaging earthquakes.