Download Strong Similarities Between Two Urban Earthquakes: Gisborne

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Strong Similarities Between Two Urban Earthquakes:
Gisborne 2007 and Newcastle 1989
Dave Brunsdon
MEng
Chair, Resilient Organisations Steering Committee
In addition to his role on the Steering Committee for the University of Canterbury-led Resilient
Organisations research programme, Dave is the National Engineering Lifelines Co-ordinator
and is a Past-President of the New Zealand Society for Earthquake Engineering. He is also
a director of Kestrel Group Ltd, a consulting practice specialising in risk and emergency
management planning for local and central government agencies and infrastructure providers.
An earthquake engineer by origin, Dave has observed first-hand the impacts of a number of
significant events including the Newcastle, Kobe, Taiwan and Padang earthquakes. He also
co-ordinated the building safety evaluation process immediately following the Gisborne
Earthquake in December 2007.
Good afternoon everyone.
The Gisborne earthquake was a definite case of déjà vu for me having worked for two years following the
Newcastle earthquake within the insurance industry and with building owners. I’m going to share some of
those similarities as part of trying to put the Gisborne earthquake into a wider and forward looking context.
I should add that the Resilient Organisations research programme hasn’t been doing any specific research
into the Gisborne earthquake, but we are involved in quite extensive longitudinal surveys or studies after
the Wenchuan in China, and L’Aquila in Italy. We are looking to work with Opus and the other natural hazards
researchers to align the findings for New Zealand.
One of the overarching similarities between the Newcastle earthquake and the Gisborne earthquake is, of
course, broken bricks on the ground (Figures 1a and 1b).
Both Newcastle and Gisborne were indicator events: moderate in the scheme of things, but pointers to
some of the issues that would need to be dealt with in a larger event. I will come back to that a bit later on.
Figure 1a: Fallen Bricks - Gisborne
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Figure 1b: Fallen Bricks - Newcastle
Strong Similarities Between Two Urban Earthquakes: Gisborne 2007 and Newcastle 1989
The five areas of similarity that I’m just going to briefly touch on today are:
1. The physical and economic context of the region;
2. The earthquake event and physical effects (that Noel’s already been through in a bit of detail);
3. The response, the issues in assessing the safety of buildings immediately after;
4. The recovery of the built environment, and the fact that the reconstruction standards are actually quite
poorly defined (as the previous speakers have eluded to); and,
5. The challenge for engineers around investigation and reporting.
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The Physical and Economic Context
There are some striking similarities there in the sense that both cities are long-established regional centres,
hubs of a larger surrounding area. They are both dominated by older brick buildings, along with some
newer ones, but with a clear vulnerability to earthquake events. Again, like a number of other New Zealand
centres that we could think of, the earthquakes struck Newcastle and Gisborne when the regions were not
prospering economically. This means that when the earthquake hit, they had some additional economic
issues to deal with. Gisborne was also subject to our recession last year.
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The Earthquake Event and Physical Effects
Moving on to look at the earthquake event (and again just quickly going through this, because it has already
been covered), the magnitudes were different but the felt intensities were fundamentally similar. Newcastle
was a magnitude 5.6 earthquake, with a peak MM intensity of 8, while Gisborne was a magnitude 6.6 event,
with the same peak MM intensity (see Figure 2).
The extract of the isoseismal from Newcastle (Figure 3) shows MM8 over a large part of the Newcastle region.
This plot also shows the red for the areas of fill overlying alluvium and green for alluvial areas. These alluvial
areas made the damage in Newcastle that much worse. Again, like other cities and towns in New Zealand
that we might think of.
Figure 2: MM Intensity of the Gisborne Earthquake
Figure 3: Isosiemal of Newcastle Earthquake
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And the physical effects resulted in considerable damage to early brick buildings both residential and
commercial. My ‘favourite’ I think is this demolition job on the Bernina building that Noel showed the front of
(Figure 4). This is simply the loss of a whole wall off the neighbouring building that took out the newer single
storey building. Happy to say there was a good recovery story in that. I think reconstruction was probably
completed within about nine months, and they were back up and running again.
But again that just epitomises one of the main features of the Gisborne earthquake. It was the impact that
your neighbour’s building can have on your’s, not just paying attention to the strength of your own building.
You might like to take a bit of an interest in your neighbour’s building because they hold your destiny if
you’re smaller than them.
Gisborne Herald
Figure 4: Damage to the Bernina Building
Figure 5 shows similar images from the aftermath of the Newcastle earthquake. I should hasten to add that
perhaps the title of this presentation, “strong similarities”, is a bit of misnomer because the total insurance bill
from the Newcastle earthquake was some 20 times larger than the insurance bill for Gisborne. It was a large
economic loss because of the geographical spread of the damage, including buildings damaged as far away
as Sydney just by the nature of the earthquake mechanism.
There were also some notable modern structures that were damaged. In Gisborne a near new apartment
building sustained a lot more structural damage than anyone expected would happen. I can’t name the
building for ongoing legal reasons, but it parallels with the Newcastle Workers Club (Figure 6), which
sustained considerable damage in the earthquake. This was an early 70s concrete building in which a 3 or 4
storey building collapsed. I think 9 out of the 12 lives that were lost in the Newcastle earthquake perished in
that building. There were official inquiries galore, three different levels of inquiry followed that collapse, and
I believe they still didn’t come with a distinctive conclusion.
Coming back to a point that Noel made, by and large, given the scale of damage, Newcastle was fortunate. If
you think about the shot of the broken bricks on the ground, the earthquake occurred at 10.28am on 28th of
December. If that had been 10.28am at any time during the school term, all the gable ends in high parapets
that fell would have certainly claimed some young victims. In Gisborne they were fairly fortunate that the
streets, if not empty, had few patrons when the earthquake occurred.
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Strong Similarities Between Two Urban Earthquakes: Gisborne 2007 and Newcastle 1989
Figure 5: Damage to Buildings in Newcastle’s CBD
Figure 6: Damage to the Newcastle Workers’ Club
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The Process of Assessing Buildings
This element has also already been covered to some extent. The issue that any Territorial Authority faces
is how to rapidly assess the damaged structures and reopen the business district. The US base procedures
were used for the first time by New Zealanders in Gisborne (Figure 7). In 1989, the New Zealand Society for
Earthquake Engineering team had them literally thrust in their hands when they were in San Francisco on
their way back from a reconnaissance tour after the Armenia earthquake, so they had a little bit of first hand
unscheduled training. When the New Zealand Government offered three leading earthquake engineers to
the Australian Government to help after Newcastle, they found themselves implementing the traffic light
procedure there. I will leave you to do the maths between 1989 and 2007 but it took a wee while to get the
same procedure properly in place in New Zealand.
We engineers had to explain and convey the situation to the Controller and emergency services people
(Figure 8). The Police were manning the area cordons, there was a changeover of Controller, and there was
also a bevy of engineers.
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Figure 7: The Traffic Light System
Up until now I’ve talked about the built environment aspect of recovery, but one of the key outputs from
Council was the plotting of the red placarded buildings (Figure 9). This picture shows Gladstone Road, the
main drag. The yellows help us to understand where cordons could be relaxed from. Because of the scale
of the damage in Gisborne, the cordons were able to be relaxed; it took a day to go from area cordons to
building barricades – a fairly quick process for a number of reasons.
Figure 8: Explaining the Placarding to the Controller and other Emergency Services
Figure 9: Map showing Unsafe
Buildings following the Earthquake
In contrast, Newcastle had a larger number of streets affected (I don’t have the equivalent plot of theirs).
They took a safety first approach and left the cordons in place for quite a while – bearing in mind it was 28
December, not a flash time. Gisborne would say a better time than 20 December, before Christmas, but not
a flash time to get construction swinging into full effect. This was a fateful decision for a number of small and
medium enterprises, the small business element. The area cordoned took out a large part of the city and
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Strong Similarities Between Two Urban Earthquakes: Gisborne 2007 and Newcastle 1989
the takeaway bars and the coffee shops never reopened. As we go back to the concept of managing the
recovery and Alan’s cloverleaf of the recovery elements – it’s a multi faceted thing where you really do need
to very carefully balance the safety element of the built environment with the whole economic rejuvenation.
So building safety evaluation is typically thought of as a response issue, but overlaps very quickly into the
recovery.
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Reconstruction Standards
I heard John articulate well some of the issues around recovery and reconstruction standards. I’m making the
observation that they are fairly poorly defined, so the first question is: what standards and strength levels do
we repair damaged buildings to?
Surely you would think that repairs must be covered in our modern building regulatory system? But the
Building Act only really regards repairs as alterations, for which you only need to make as good as they were
before. It gets complicated where it mixes with earthquake prone policies and the desire to do a little bit of
risk reduction while you’re at it, so you’re not just building back that parapet. The Gisborne District Council
were very proactive in saying “well, if you are going to rebuild that you need to do some tie backs and do
some additional work”. Straight away that got into a dilemma - for those that were insured. But you know
back 20 years ago in Newcastle, it really was a case of “just put those bricks back guys”.
I will leave you to use your imagination, but when you are dealing with whole façades to reconstruct, if you
don’t have clear regulatory arrangements in place it makes that triangular issue between the owner, the
local authority and the insurer into much more of a battle than it needs to be. The consequences of this
situation are tensions between the parties, and as you look at it from a recovery management perspective
nothing stretches the time frame out once you get past dealing with the trauma of the event than people
not being able to get back to “normal” living if it’s a house, or a generating income if it’s their business.
Another thing that has been touched upon today is what I call “the new challenges” for engineers - forensic
investigation and reporting if you have an older building that’s damaged. If it’s a brick construction, bear
in mind no contemporary engineers have designed brick in the way in which was originally built. In the
forensic aspect, you also get into the lesser damaged areas when all sorts of cracked structures come to light
in post-earthquake insurance claims. Was the damage really due to the earthquake? Or was the owner not
being genuine when they say they hadn’t actually seen that damage before the earthquake? It is sometimes
hard to differentiate between damage caused by the earthquake, and existing damage.
As you dig a bit deeper, cracks can be fixed, but the foundation may not be good enough to support the
building. This starts to balloon out the size of the repair process, and gets into the insurance grey area.
Gisborne highlighted the need for engineers that are not trained in damaged buildings to have a good
understanding of what caused the damage, so what sort of training is involved around these issues?
For insurance, clear evidence-based analysis in reporting is required. Every insurance claim can go the extra
mile into the court system and this was a particularly big issue in Newcastle. In Gisborne because the sheer
volume of claims weren’t there, it was typically senior engineers and leading practitioners in firms that were
doing the reporting. However in Newcastle the huge volume of claims meant that many cases were given
over to some of the younger engineers with minimal training. This leads us back to the possibility of a bigger
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earthquake in New Zealand – we don’t have enough engineers with adequate training. There is a strong case
for more structure and training around this.
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The Similarities between Newcastle and Gisborne
Recapping the similarities:
1. The physical and economic context;
2 The earthquake event and physical effects;
3. The response – a new process for assessing buildings;
4. The recovery of the built environment – poorly defined reconstruction standards; and,
5. The challenges for engineers – forensic investigation and reporting.
I’ll come back to the point that the Gisborne earthquake was an indicator event – or should be - highlighting
the things that actually do need to be addressed to enable an efficient response to a bigger event in New
Zealand. Gisborne has already been regarded in some circles as the forgotten earthquake because some of
the actions haven’t actually flowed on.
If we want to sort of pose a provocative question at the end, you can say – well, consider the 20 December
2010 ‘mid-town’ New Zealand earthquake. We won’t impose a Christmas meltdown on anyone this year, but
if an earthquake was to occur of a slightly larger nature, would the built environment response and recovery
go as smoothly as it did in Gisborne? These are some of the questions I would like to leave you to ponder as
we look at Gisborne in a wider and hopefully forward-looking context:
»» Are there arrangements in place to support the ‘Mid-town’ District Council with their building safety
evaluation?
»» Are repair standards for pre-modern code buildings better defined?
»» Can we better explain the interface with the insurance sector for professionals and the general public?
»» Is there a leader for the Built Environment task group? Is the person that will actually have to manage
this process identified or designated and trained?
Thank you.
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Questions
Anon:
Hi Dave, thanks for that, that was really interesting. When comparing them, the building code that was in
Newcastle at the time, did that involve a certain amount of earthquake engineering similar to our code?
Dave:
It didn’t, no is the short answer. They had unreinforced un-designed brick work, but again that’s how a lot of
buildings in early New Zealand have started out too and sit today. But one of the positives of the Newcastle
earthquake was that they already had a draft earthquake code ready to go before the earthquake, and they
put it out shortly thereafter.
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Strong Similarities Between Two Urban Earthquakes: Gisborne 2007 and Newcastle 1989