Frequently Asked Questions - Earthquake Prone Buildings
Why is Nelson City Council evaluating all its buildings for earthquake risk?
New Zealand has a relatively high earthquake risk, which has become particularly evident following the devastating Christchurch earthquakes. It is important for safety reasons that buildings that are seismically weak are upgraded to be safer in a damage causing quake.
All councils in New Zealand are required by the Building Act 2004 to have a policy on earthquake-prone, dangerous and insanitary buildings. Nelson City Council’s earthquake prone buildings policy adopts a staged approach to reducing earthquake risk, starting with identifying buildings that may be earthquake prone. This policy applies to all landowners including Council, which has approximately 100 buildings and 40 other facilities such as toilets, sheds and bridges that require evaluation.
What is the process for deciding whether a building is earthquake prone?
The process to determine whether a building is potentially earthquake prone comprises two distinct steps that measure the strength of the building against a new building’s strength.
The first step is a table top evaluation by a building owners structural engineer who delivers an initial rating, which is then compared to a set of criteria to determine if a detailed evaluation is required. If the initial rating is above 33% of the New Building Standard (the standard to which an equivalent new building would have to be built), then no detailed evaluation is required.
If the rating is below 33% of the New Building Standard, the building is deemed potentially earthquake prone and a detailed evaluation is required. This second evaluation involves examining the building in much closer detail. Alternatively, the building owner could accept the findings of the initial evaluation and that the building is earthquake prone. This alternative need to be discussed with the councils structural engineer so agreement can be made on any subsequent action required by the building owner.
When the initial and/or detailed evaluations, council will review and discuss the required actions and timeframes with the building owner. The Authority may then issue a Section 124 Notice declaring the building Earthquake Prone. This notice will come with conditions advising the owners of the building what actions they have to take and by what date these conditions have to be met.
What happens next?
Deciding the future of any Council-owned building that is declared Earthquake Prone will be made on a case-by-case basis. Council needs to consider all the issues relating to each individual building (including strengthening costs and lease agreements with existing tenants) before deciding whether to strengthen, demolish or take another course of action. Staff will formally take a report to Council for a decision on each individual building.
When did the review process start?
Given the large number of buildings involved, the significant costs associated with earthquake evaluations and potential strengthening work, and the shortage of structural engineers throughout New Zealand (as this is the same process all Councils and private building owners are following), this is a long term project and likely to take many years to complete.
Unfortunately, no quick decisions can be made and more often than not, it will be business as usual in the interim.
Is there an increased risk once a building has been deemed “earthquake prone”?
It is very important to emphasise that there is no new risk or imminent danger following an evaluation determining that a building is earthquake prone, than before the earthquake evaluation was made.
More information
For further information about Council’s earthquake evaluations, please contact the Customer Service Centre, phone +64 3 546 0200.
