Has Dunedin learned quake lessons?


We watched in horror as Christchurch was shaken to its core. But has Dunedin learned the lessons? Paul Gorman investigates.

Christchurch never stood a chance.

Sure, there had been warnings over the years about large earthquakes from faults elsewhere in Canterbury, some buildings had been quake-strengthened, and "may be prone to liquefaction" was written on most property owners’ titles.

But when the magnitude 7.1 Darfield earthquake came on September 4, 2010, it went beyond all that.

Then the magnitude 6.2 Christchurch quake struck on February 22, 2011, killing 185 people and wrecking the central city. The city also lost more than 200 heritage buildings as a result of the earthquake sequence of 2010 and 2011.

In Christchurch the two buildings that killed the most people in the February, 2011 earthquake...
In Christchurch the two buildings that killed the most people in the February, 2011 earthquake were newer, including the CTV building in Madras St. PHOTO: STEPHEN JAQUIERY

Could the same thing happen here? Heritage buildings are everywhere in Dunedin. Part of the fabric of the city, acting as a significant magnet for tourists.

Enterprise Dunedin estimates heritage alone may have brought close to $100 million into the city last year.

The impact of a major earthquake on Dunedin’s heritage coffers is likely to be far worse than it was in Christchurch.

Long-time Dunedin heritage advocate Lois Galer says Dunedin is older than Christchurch and has more heritage buildings.

"It would be a terrible, terrible thing to see buildings like that coming down around our ears."

So, what lessons has Dunedin learned from Christchurch, in terms of guarding and strengthening its heritage stock and protecting its citizens?

Gazing across the Octagon from his office balcony, Dunedin Mayor Aaron Hawkins says the city is fortunate to still have many of its heritage buildings, although, to some extent, heritage is in the eye of the beholder.

"You think a 19th century weatherboard villa is high maintenance? Try owning an early century Edwardian masonry building.

"Dunedin was lucky in that there was a lot of money in the city at a time when people were designing and building grand Edwardian-style buildings. Then there wasn’t a lot of money or interest at a point when in most other cities around the country those were being demolished and replaced by new international-style glass tower buildings.

"They were just lying around, waiting for a resurgence in interest; to adapt them for reuse, to strengthen them, to bring them back to life. Really that has only been in the last decade - and it accelerated in the last five years - that the volume of that architecture has been brought back to life."

The original drafting of the Earthquake Prone Buildings legislation after the February 2011 earthquake "made a lot of people here very nervous", with its single timeline for all buildings to be brought up to a certain standard, Hawkins says.

"Through lobbying through local government - Dunedin was particularly strong on it - we got that amended to a more nuanced or risk-based approach for work where we have longer timeframes in lower-risk seismic areas.

"We have more time to do that work, but you could always do more - close to 35 years, up to about 2050."

The February quake caused concern for the future of heritage buildings in New Zealand, he says.

"In terms of the damage, in terms of loss of life, it wasn’t heritage buildings in Christchurch that was the issue, it was modernist buildings built mid-century."

Southern Heritage Trust trustee and Dunedin Heritage Fund committee member Jo Galer says Dunedin "would be foolish not to be prepared" for a major earthquake.

"Knowing the science, it is quite possible that could happen, and we need to be prepared and ensure our buildings are safe for people to work in and live in and walk around.

Heritage advocate Lois Galer. Photo: supplied
Heritage advocate Lois Galer. Photo: supplied
"We have to take it seriously, but at the same time we can’t use it as an excuse to knock down old buildings or our heritage - we have to seek very good advice and engineers’ reports and do the work properly.

"In Christchurch the two buildings that killed the most people were newer - the CTV and PGC buildings. So we may have some newer buildings here which don’t comply, that’s highly likely. Let’s not just think it’s our heritage buildings in the spotlight.

"Even though we remember that 1974 [Dunedin] earthquake, we went through a period where we felt we were almost six-feet tall and bullet-proof, absolutely nothing was ever going to happen to our buildings, that earthquakes just didn’t happen. Christchurch changed all that."

University of Otago chair of earthquake science Prof Mark Stirling works in one of the most historic and potentially vulnerable stone buildings on the Dunedin campus.

"I work in the geology department and that building is an unreinforced 1870s building - unreinforced masonry. It has been retrofitted to about 30% of code, but you know the biggest lecture theatre, when it empties out, my office shakes. And a brick building shouldn’t shake - it’s meant to be a rigid building.

"So that scared me the first time I felt that in my office and I thought it was a Fiordland earthquake, but then I realised it happened every time the lecture theatre emptied out. But it just gives you an idea of ‘that’s not right’, so I’m glad that our university is doing something about the earthquake issue.

"I have a lot of confidence in the university - I’m part of the seismic steering committee that’s going through and looking at the most earthquake-prone buildings and doing something about it, whether it’s retrofitting or changing the use of the building, or decanting the building completely and looking at mothballing it and pulling it down."

Dunedin City Council heritage adviser Dr Andrea Farminer says the city has 763 scheduled heritage buildings and 922 character-contributing buildings - "a lower level of heritage protection".

Of the heritage buildings, 108 are category one historic places and 217 are category two on the New Zealand Heritage List.

About 40 of the character-contributing buildings are on the Earthquake Prone Building Register (EQPB), and 307 heritage buildings, as of 2016.

That register is about to be updated.

"The balance of heritage buildings not on the register are likely to be timber buildings and/or were not required to be assessed under the Building Act, as they were not commercial buildings, or residential buildings of two or more storeys and three or more household units, and/or used for hotel and other types of accommodation."

Dr Andrea Farminer. Photo: supplied
Dr Andrea Farminer. Photo: supplied

Of the 347 historic buildings on the register as at 2016, 56 are category one - including the Dunedin Railway Station, Knox Church, and the Regent Theatre - and 83 are category two.

Seventy percent (244) have yet to be assessed for earthquake risk, 69 (20%) have been assessed, 22 (6%) were earthquake strengthened by 2016 and 12 (4%) had been reassessed as not needing to be on the register.

Of the 69 heritage buildings that had been seismically assessed by 2016, 20 are likely to be earthquake prone, Dr Farminer says.

"What we do not know yet, until the new earthquake compliance officer completes his initial work, is how many heritage buildings have been seismically upgraded since 2016.

"[But] we have provided heritage grants for 23 historic building seismic assesements and upgrades since 2016."

The council has provided more than $1.3 million to heritage building owners to support seismic assessments and upgrading in the past nine years.

As part of that, the Dunedin Heritage Fund has handed out 58 grants since 2011 worth $914,658.00, excluding GST. The remainder has come through rates-relief grants on heritage reuse projects.

Mayor Hawkins says what can be done to strengthen and tidy up heritage buildings is astonishing.

"When I moved here nearly 20 years ago, unless you were squatting or had a band room there, nobody would ever think about spending time in what is now known as the Warehouse Precinct. But that has become in a relatively short period of time a huge source of civic pride.

"It is remarkable the amount of work that’s been done and the amount of investment that has gone into the adaptive reuse of heritage buildings. The city has been very supportive of that work through the heritage fund."

A group of developers with a "fresh, new attitude" have recognised the city’s heritage buildings...
A group of developers with a "fresh, new attitude" have recognised the city’s heritage buildings and put them to new uses, including in Dunedin’s warehouse precinct.
A strong public campaign convinced the Government to spend more money than it had probably wanted to on the Dunedin Law Courts. That complemented earlier work by the city and community to "refurbish and repurpose the Dunedin Railway Station, which is an iconic architectural asset".

But there are examples on Princes St, particularly, of "effectively demolition-by-neglect".

"It is not all sinister. Sadly some of these buildings are run by people who genuinely don’t have the resources to do the work that is required to bring them up to spec."

Otakou kaumatua Edward Ellison (Ngai Tahu and Te Atiawa) says past heritage funding has been "heavily weighted" towards the preservation of buildings rather than cultural, tangata whenua, heritage. Well-embedded trusts had the inside-running on disbursements.

But he doesn’t "have an issue" with protecting and strengthening heritage buildings.

"I like Dunedin like it is - I couldn’t live in a modern city with modern buildings, just too boring.

"Dunedin is distinctive, and because of our slow growth rate we have managed to retain a lot of those old buildings - the railway station, and numerous other buildings. They’re just fabulous."

Enterprise Dunedin director John Christie says calculating the value of heritage to the city is a "complex piece of analysis", involving tangible factors and intangibles, "such as how heritage makes people feel by supporting their sense of place and identity".

One index, the Tourism Sentiment Index, shows that 12% of all online conversations about Dunedin in January and February this year related to heritage.

Assuming those online chats fairly reflect desires to travel to Dunedin for its heritage, then 12% of the total visitor spend last year in the city of $775 million equals about $93 million, Christie says.

University of Otago chief operations officer Stephen Willis.
University of Otago chief operations officer Stephen Willis.

Jo Galer says those tourist dollars are critical, providing the economic imperative to retain and strengthen heritage buildings.

"Without that, you wouldn’t get people renting them or using them. It just won’t happen.

"Heritage, along with wildlife, are the two main reasons why people come to Dunedin. It is just part of the picture overall of a very stunning and beautiful city that people want to see."

A group of developers with a "fresh, new attitude" recognise the city’s heritage as desirable and adding vibrancy, including Stephen McKnight and family, Laurie Forbes, Ted Daniels, Guy Shallard, Tony Sycamore and Chris James.

"A lot of tough negotiations go on behind the scenes to ensure the protection of the city’s heritage from earthquakes," she says.

Lois Galer champions strengthening, "if it’s seen to be necessary".

"I certainly don’t like to see buildings demolished because they might be earthquake-prone, and that was always a fear.

"You get building owners saying, ‘I’ve got to pull it down’, and I’d say, ‘well, you’ll have an engineer’s report of course?’."

Prof Stirling says the New Building Standard (NBS), colloquially known as the "code", differs around New Zealand, depending on the assessment of the seismic hazard.

In Dunedin, the 500-year return period hazard for ground motion based on all sources in the area has been calculated as about 0.1g, one-tenth the acceleration of gravity.

"If 0.1g is100% of code, then a building assessed at, say, 45% of code is 0.1g multiplied by 0.45, or 0.045g.

"Unfortunately, 0.1g is a low number relative to the shaking that would actually be experienced during a large earthquake on an active local fault like the Akatore Fault."

During the February 2011 Christchurch earthquake, vertical ground accelerations reached a phenomenal 2.2g at Heathcote, although GNS Science has been investigating the legitimacy of that figure.

In an Official Information Act response, the University of Otago says its strengthening programme focuses on pre-1976 buildings identified as of seismic interest.

The Registrar’s Office withheld detailed costs of previous strengthening work and estimated future costs citing commercial sensitivity and claiming their release could prejudice future negotiations.

However, chief operating officer Stephen Willis says the recent spend has been in the "millions" and more than $100 million could be spent on strengthening in the next 10 years or so, depending on affordability and Covid-19.

The university also declined to release reports on strengthening from the past decade, although it "accepts that there is public interest in the seismic strength status of its buildings".

Willis says the university reviewed the condition of its buildings in 2017 to prioritise work, seismic rating one criteria.

Top priorities for earthquake upgrades/strengthening, Covid-19 allowing, include:

• The Consumer and Applied Sciences Building (1920), which only meets 15% of the New Building Standard (NBS) for Dunedin - occupants have been temporarily relocated.

• Physical Education Building (1910), 23-26% of NBS - occupants have been temporarily relocated.

• Union Court (1930), 27% of NBS - occupants will be relocated and the building demolished next year.

• Adams Building (1973), 30% of NBS - upper floor vacated and work under way to add restraints to the block spandrel panels. A replacement building is planned in the next 10-year plan. but will be subject to post Covid-19 affordability.

• Property Services (1920), 25% of NBS - planning under way to relocate the occupants and demolish the building when affordable.

• Scott Building (1918), 25% of NBS.

• 71 Frederick St (1910), no NBS listed - occupants will be relocated and the building demolished within the next 10 years if affordable.

A seismic steering committee is also looking at other more minor work, Willis says.

"A significant portion of our planned pre-Covid capital plan had seismic strengthening as a major driver.

"The speed at which we are identifying and strengthening buildings in Dunedin substantially exceeds the expectations set by legislation."

A public survey two years ago showed nearly 90% of city residents thought an earthquake was a...
A public survey two years ago showed nearly 90% of city residents thought an earthquake was a risk to them.
How prepared are Dunedin residents for a major earthquake?

Hawkins says residents’ awareness of quake risk "ebbs and flows" with the news cycle.

"It’s an ongoing piece of work to escalate people’s preparedness, but you want to do that in a way that doesn’t panic people."

Emergency Management Otago Dunedin team leader Glenn Mitchell says a public survey two years ago showed nearly 90% of city residents thought an earthquake was a risk to them.

"Which is heartening. If people aren’t experiencing these things, it kind of falls off the radar. Similarly, if people have a relatively innocuous experience with a hazard, such as an earthquake - there’s a rumbling and a shake, things rattle, and that’s it - it would be easy to become complacent.

"The challenge is for the community to understand that the impact of an earthquake in Dunedin is [potentially] as much as Christchurch."

Aaron Hawkins. Photo: supplied
Aaron Hawkins. Photo: supplied

Mayor Aaron Hawkins says another awareness survey is scheduled for next year.

"I’ll certainly be interested to see what the survey spits out, see if that dial has shifted or not. That will tell us how much more work we need to do to build up that preparedness."

Mitchell believes the worst-case scenario for Dunedin might be "a week of decent rain and everything is soaking wet and then you give it a good shake".

"Dunedin is reasonably well prepared. Going by that recent survey, 60-odd percent said they were reasonably- or well-prepared, but I take more heart from the anecdotal evidence we are getting.

"A reasonable parallel is the Covid response during level 4, how communities worked together and identified people in the community who may not necessarily be able to support themselves, or go to the supermarket or whatever.

"There’s a much stronger focus now on, rather than you as an individual or a family being able to cope for a period of time, it is how a community can cope. I have got reasonably good confidence that our communities will cope."

There is "an element of quiet confidence, rightly or wrongly" that Dunedin’s heritage buildings may escape significant damage in a large earthquake because of the ground structure, he says.

"The likes of First Church on Bell Hill is on pretty solid rock and shouldn’t experience the same kind of impact as Christ Church Cathedral did.

"Flip side to that is, of course, South Dunedin has a very different ground structure and so we are likely to see significant damage. We relate South Dunedin to the eastern suburbs of Christchurch - we are going to go through the same experiences."

Retiring Dunedin South Labour MP Clare Curran says the big risk to the electorate in the event of a major earthquake is liquefaction.

Clare Curran. Photo: Twitter
Clare Curran. Photo: Twitter
"Thankfully GNS is doing a lot of work on what lies beneath and how the water flows, or doesn’t, so we have more scientific evidence around what happens with rising sea-levels or big storms and also with earthquakes.

"The other issue is if there was to be a tsunami as a result of an earthquake, and we have quite serious vulnerabilities along the coastline here.

"There is a lot more preparedness for disasters since the 2015 flood, which affected more than 1000 homes with sewage-ridden water.

"Ever since then, Civil Defence has really pulled its finger out ... and worked a lot with the local community to make sure people are aware of where to go, how to respond, how to look after each other.

"I feel quite heartened by that. Often it does take a disaster for those sorts of things to improve."

South Dunedin has its own identity and is resilient, she says.

So, is Dunedin ready?

It seems more prepared than Christchurch was.

It has no excuse not to be, given what happened up the road.

- This series of features and online content was made possible by a grant from the Aotearoa-New Zealand Science Journalism Fund and EQC. Online content produced and edited by ODT videographer Rudy Adrian.

 

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