Assessing the Wellington quake shake

  • August 14, 2013
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Kestrel’s Dave Brunsdon helped co-ordinate the rapid impact assessment of buildings in the Wellington CBD following the 20 July 6.5 Cook Strait earthquake.

For Dave this meant hitting the ground running at first light on Monday morning helping to organise operations for Wellington City Council’s Building Control Unit, reporting through to the City’s Civil Defence Emergency Management Group Controller. He was working alongside key MBIE and MCDEM representatives, and leading Wellington consulting engineers.

“The nature of the earthquake meant that medium-rise buildings (e.g. those six to 10 storeys high) experienced the most damaging shaking. Low-rise stiffer buildings typically received less shaking, hence there were few instances of damage to unreinforced masonry buildings,” says Dave.

“The key exterior hazard features that the engineering teams were looking for included structural damage such as cracks in main structures like columns and walls, and signs of loose concrete and masonry.”

“We were also looking at non-structural façade damage like broken glass or other items that could fall off buildings in aftershocks or strong winds,” he says.

Whilst the engineering teams were looking at general public safety risks, it was still up to individual owners to assess damage to their own buildings and have these looked at by a structural engineer where necessary.

“It was really heartening to be able to quickly form the view that most buildings in Wellington are in no worse state than before the earthquake. Most of the damage was either structurally superficial, typically involving parts of buildings moving relative to each other or neighbouring buildings, or involved the failure of elements such as water pipes and ceiling systems.”

Dave did say, however, that this event was a timely reminder that earthquakes can happen at any time without warning.

“Although by and large buildings performed well and sustained little structural damage, it is much better for building owners to be pro-active in getting buildings assessed prior to earthquakes to understand how they are likely to perform, and getting work done on them to reduce risk.”

He also says it’s important to remember that just because a building has sustained little damage this time does not mean that there is no risk in future events (e.g. larger earthquakes or those with different shaking characteristics).

”This process has helped establish a national template for a rapid impact assessment of CBD areas in minor to moderate earthquake events”.

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