The Eye of the Fish

Maximus
July 21, 2013

Earthquake: over-reaction?

Whilst I am fully aware that was a nasty series of shakes on Sunday evening, and indeed over the last few days, I’m very disappointed in the over-reaction of the media to this seismic event. RadioNZ reported that a building in Featherston St had a collapsed concrete facade – I don’t know about you, but I thought “Crikey! If a concrete facade can collapse, then what about the brick facades in Cuba St!” – and so I set off to find out which building had collapsed. As it turns out, none of them. In another world exclusive Eye of the Fish news flash, I can report to you all that Old Wool House and New Wool House evidently jostled together (I wouldn’t even call it pounding), and some small fragments of plaster edging fell to the street below – primarily because the facade had already cracked years ago, with rusting steel reinforcing visible inside. I’d say that the earthquake didn’t even cause the damage, it was there before – the quake just hastened it to make its way to the ground.

RadioNZ also reported that some asphalt roadways had cracked and areas of paving were being thrown up – again, I don’t believe this was actually true – certainly, having had a thorough scout around town, I could see virtually no sign of damage. I’d say that Katrina Batten, the DJ on air at the time, just made matters worse by saying stupid comments like “if our building is still standing” about the RadioNZ House, when quite clearly not a single high rise building had collapsed – in fact, not a single building of any sort at all appears to have collapsed. Except a fence.

But that’s not to say that we should not be worried. The area that the quakes originate, in the middle of the Cook Strait, is the junction between the two continental plates. We all know that the Pacific Plate and the Australian Plate are attempting to slide past each other, it is one of the reasons that NZ has a strong seismic activity profile. What is perhaps not so well known is that on one island, the Pacific Plate is above the Aussie one, and on the other island, the Aussie is above the Pacific. In other words, the two plates are stuck, binding on each other, and at some stage there will be an almighty great rupture and a bang as the energy disappates and the plates move. And, if I understand correctly, that crossover in the subduction zone occurs pretty much underneath Wellington and in the middle of the Cook Strait. And putting it bluntly, when that goes, we’re all fucked. There must be a more polite term, but right now, I can’t think of one, sorry. So, seeing as we are having a continuous series of bangs and shudders and creaks of evident earth movements from that particular location right on the surface between the two plates, I would have thought would be bringing more cause for alarm. Forget today’s little temblor – the big one is yet to come.

Update: Earthquake Report from Fish Central
Despite the headquarters of the Eye of the Fish being composed of many piles of important documents, and so hence apparently in an earthquake-prone, ready to slide formation, all that fell over was one birthday card, tragically toppled to the ground, one emergency transistor radio also toppled – the cause of the one incident above, and a small plastic figurine of Bender, who is inherently unstable anyhow (due to alcohol and bendy legs). Oooh, and a bottle of wine lying on its side, but i can’t guarantee that was not due to other causes. Yes, I know, Wellington got off lightly – but we SHOULD be at a state where we can ride out a Quake with no more damage than that.

GNS
21 - 07 - 13

From Geonet:
The period of seismicity began with a magnitude 5.7 on Friday morning, just after 9.00 am. This evening’s 6.5 was in a similar location to the previous earthquakes and was caused by similar stresses as the previous greater than 5.0 earthquakes. However, initial indications are that whereas the earlier events were dominated by thrusting motion (one plate riding over another), the 6.5 was dominantly transverse (side-to-side) movement. Crustal events typically have extended aftershock sequences and more felt earthquakes are expected.

GNS Science believes the sequence is in the overlying plate, above the subduction interface. In this area, the Australian plate overlies the subducting Pacific plate at a depth of about 25 km. Many crustal faults have been mapped in the area, however the exact fault(s) upon which the events have occurred is yet to be determined.

Through the weekend, the seismicity has moved to the south-west. This migratory behaviour is commonly seen in seismic swarms and is typically believed to result from the outward transferring of stress from the earlier events to the later ones. Historically, the region has seen other seismic swarm activity. Most recently, in 2005 a series of four earthquakes greater than 5.0 occurred about 10 to 15 km to the south-west of the current swarm; these earthquakes caused no damage.

Statistical analysis of the sequence to date provides estimates of the probability of future earthquakes in central New Zealand. GNS Science estimates that in the coming week there could be up to nine magnitude 5.0 or greater events, with an approximately 30% probability (a 1 in 3 chance) of a magnitude 6.0 or greater. The most likely period for this to occur is the next 24 hours, when the probability is approximately 20% (a 1 in 5 chance).

Earthquakes less than magnitude 7.0 do not usually generate a tsunami; however, it is possible for undersea landslides triggered by earthquake shaking to produce a tsunami. The impact of these types of tsunami is usually confined to the coastline close to the earthquake epicentre, and would reach the coast within 10 to 20 minutes following the earthquake.

Happy
22 - 07 - 13

Harden the fuck up, people! The Dom Post reports “considerable damage” and yet that appears to be confined to about a dozen broken windows over the entire city. Sooo much fuss over nothing.

Ringadingding
22 - 07 - 13

Has anyone checked – did Ken Ring foretell these?

starkive
22 - 07 - 13

He appears to have evacuated.

60 MPa
22 - 07 - 13

Yeah nothing like Chch – I believe that Blenheim had it worst
Traffic this morning will be bad and there’s a big crack in Kings Wharf where the Bluebridge docks but overall I rather enjoyed that wee swarm

m-d
22 - 07 - 13

Someone please tell Cantabrians that the media hype in no way reflects our own response to the quakes. I feel a deep embarrassment over how this is being reported on our behalf.

Inner City Suburbanite
22 - 07 - 13

Traffic this morning was a breeze. I live in the city and work in the Hutt, traffic out was normal – but the lanes coming in were deserted, people have obviously listened to the requests to stay at home and enjoy a morning off. The jolt yesterday afternoon was the first shake I’ve felt that I haven’t enjoyed.

davidp
22 - 07 - 13

There are some nasty cracks on the exterior of the ground floor of the Sharp building in Taranaki St.

What was happening at the Regional Council building in Wakefield St last night. Water was pouring out the windows on three sides. How does it come out the windows? Was it waist deep in water?

denny
22 - 07 - 13

I love it that the CBD is deserted and Cuba Street is abuzz with people… shows the real interpretation of things by people who don’t care for the media hype…

It seems the worst toll has been on bottled goods rather than buildings http://www.stuff.co.nz/national/8949025/Quake-takes-out-the-good-stuff. personally, I agree that this has been an over-reaction by the media and hope that it doesn’t grow in to anything worse. It is a real pity the media ‘loves a story’ to the point of focusing on the small and avoiding the big picture. As you rightly point out, though something reasonably significant did happen, it is real perspective that helps joe citizen not get complacent through people seeming to ‘cry wolf’.

Interesting effects include the reclaimed land around the container terminal (the result of knocking over ‘earthquake prone’ buildings in the 70’s) – this seems to have shown some unexpected weaknesses. The rest of the town appears to have survived with very light damage despite a 1/8th G lateral load being applied to some ‘earthquake prone’ buildings. Yes this is around 0.1 of the force Christchurch was subjected to but it is a fairly good guide as to our building’s ability to withstand a quake or two. I’m writing this in a URM building that is over 100 years old, knowing it can take a few hard jolts without even showing a crack gives me great confidence.

On the plus sides of the media hype, the bus ride to work this morning was one of the quickest I’ve ever had…

davidp
22 - 07 - 13

I’ve been out for a look around town, and I’m surprised that the entire civic center is cordoned off. Including the little park with the rugby sculpture. Is this just a massive over-reaction, or is there a real issue with all the civic center buildings?

Maximus
22 - 07 - 13

Davidp – the black overbridge entry bit of Athfields civic building was identified a while back as an earthquake hazard, and I believe it lived up to its hype. They have evacuated it and reported that it has cracks – whether just in the windows, or in the floors or walls is not clear. But I think it has just signed its own death warrant, and will be coming down within the next year. For that reason, they don’t want people walking under it – 800 tonnes of unstable building poised up there.

Maximus
22 - 07 - 13

Hmmm. For the first time, I find myself in full agreement with John Key and John Morrison.
http://www.stuff.co.nz/the-press/news/8947876/Quake-damage-not-tremendously-significant

http://wellington.scoop.co.nz/?p=57582

Well done chaps!

davidp
23 - 07 - 13

But does the bridge warrant cordoning off bits of the civic center 100m away? Surely it can’t be the most dangerous structure in the CBD. Buildings that have actually suffered actual damage have just the footpath closed to stop debris falling on people, but the entire civic center complex was roped off yesterday. With HOT ZONE tape in some cases. which I found funny because that is the title of Richard Preston’s book about ebola.

Is this just the council trying to appear super cautious? After all, the Taranaki St Wharf jump platform has been closed for months now due to the supposed toxic properties of the harbour. Or are people talking up the effects of the earthquake in order to get themselves a couple of days holiday?

Maximus
23 - 07 - 13

I’ll have to leave that to the officials at WCC to answer, as I just don’t know. Perhaps they have closed off the other end of Civic Square so that they don’t get people wandering 9/10 way through the Square, and then having to be turned back. (cos I too would be tempted to duck under the Hot Zone tape and keep going, rather than walk back round). Or perhaps it is because the building at the other end, the Capital E structure is also declared EQP, and vacant. But most of all I would say that Yes, the black box portico probably is the most dangerous building in Wellington at present, not because it is particularly more likely to collapse, but because if it did, it would surely cause a huge amount of damage – effectively dropping a building from 3 floors up onto the ground is going to make a heck of a bang.

We wrote about that building a few months ago, http://eyeofthefish.org/meh-portico/ and noted that the Engineer of the building probably has some pretty serious questions to answer. I’d really like to hear some answers from him about how risky the building is.

Phil
23 - 07 - 13

It doesn’t feel like an overreaction to me and I wonder if it depends on the structure you were in when it occurred. I was in a waterfront restaurant and it got a big sway on, plates and glass flew at our heads and it generally felt very damaging. those in highrise apartments also saw their stuff fly around the place. If a bit of hype forces us to remember to attach our bookcases and pushes building upgrades ahead then I’m not going to complain.

Maximus
23 - 07 - 13

Phil – tell us more. What restaurant? I’d be interested to know. For instance, Shed 5 is low to the ground, but is on piles and next to reclaimed land. Portofino, on the other hand, in the Meridian building, is in a similar situation, but in a much stronger building. The BNZ building at Harbour Quays – evidently not so robust in the ceiling department.

I guess my angle is that when there is serious damage, then it is time for serious talk. When you live in a city which is on a major series of known earthquake faults, then you should not exacerbate the situation by exaggerating the effect – nearly all the broken windows in the city were from one floor of one building. The top floor (an extension, not part of the original design) of the Farmers Coop building (i think that is its name) in Featherston St, which is one of the oldest buildings in the city and sits on reclaimed land not far from the harbour’s edge.

Maximus
23 - 07 - 13

Actually, i’ll correct myself there – it was not the top floor, it was 2 floors below the top, and so it was part of the original building, and not the rooftop addition (that bit probably put the extra strain on the top floors).

Phil
23 - 07 - 13

It was indeed Shed 5/The Crab Shack. My guess is it was swaying on those piles. We were surprised that there wasn’t more damage in town as it seemed like every plate in the restaurant broke.I see your point but I’m not sure a bit of panic is a bad thing if it puts the pressure on building owners to upgrade their buildings.

davidp
23 - 07 - 13

Max>We wrote about that building a few months ago, http://eyeofthefish.org/meh-portico/ and noted that the Engineer of the building probably has some pretty serious questions to answer. I’d really like to hear some answers from him about how risky the building is.

The only buildings cordoned off today seem to be the two in Featherston St that were slamming in to each other, and the bridge offices at the civic center. Really old dodgy looking brick structures such as the building that backs on to the Salvation Army car park are just fine. That means the city council have managed to build themselves one of the most dangerous buildings constructed in Wellington in the last hundred years, and they did it recently.

Either the building standards the council mandated in the nineties were spectacularly wrong. Or their consenting checks were bad. Or there was something criminal going on… Maybe the architect lied in the paperwork and the consenting staff didn’t pick it up, or the consenting staff realised the bridge was dangerous but looked the other way because this was a city council owned building. Regardless, should the same city council be setting and enforcing building standards now? Shouldn’t there be an inquiry to understand how the council got it so wrong?

Maximus
23 - 07 - 13

davidp – absolutely! “That means the city council have managed to build themselves one of the most dangerous buildings constructed in Wellington in the last hundred years, and they did it recently.”

yes. Questions should be being asked…

Peter
24 - 07 - 13

Maximus, the building you referred to above is the Dominion Farmers Institute building (http://dayout.co.nz/attractions/attraction.aspx?attractionId=2227). The footpath adjacent to the building is still closed as the glaziers are still on the job. No doubt the glass is very old and brittle, probably only 3 or 4mm plain float. the fixing medium (putty?) is no doubt quite ancient and solid judging by the effort required to clean it out of the steel frames. It will be interesting to see if the remaining windows will now be ‘sorted’ since so many went in the earthquake.

Maximus
24 - 07 - 13

Peter, that’s right – thank you. Perfect answer too. Many buildings around town have glazing in seismic frames nowadays, and so don’t have that problem. But i do wonder why it was that the second to top (original) floor suffered the most damage, rather than the top (original floor). Who knows? One possible answer could be that the “bay windows” have a relatively solid frame around them, and that the gabled parapets above them have a slightly different structural system, which is why they did not flex as much? But i suspect we will never know.

Maximus
25 - 07 - 13

Confusing reports flying around about the big Black Box Portico at the WCC – some sources say it is only superficial damage, and will be reoccupied soon – others say it is damaged goods and will be demolished early next year. That seems a bit of an over-reaction to me – presumably, as we noted before, the building is fixed at one end (the WCC end) and sliding with a massive seismic joint opposite (at the Library end). The only real catastrophic situation would be if the box slid right out of its seismic movement joint, and, unsupported, crashed to the ground. It’d make quite a thud (800 tonnes = loud noise). I’m guessing that they can’t just weld the joint shut (or else the mass of the building in a quake could shunt the Library building over), and so my solution is: MORE LEGS ! ie independent suspension for the Portico to walk around on, should the need arise. That could be cool! Much moire fun than just demolition and an empty hole…

davidp
25 - 07 - 13

There seemed to be water coming out of the portico on Sunday night. From the library end, running down the library wall.

It might be interesting to look at the performance of earthquake-prone vs “safe” buildings. There are a lot of stickered buildings that have sustained no damage at all, even tho some of them look like piles of randomly arranged bricks. On the other hand, NEC and Sharp (both on Taranaki St) are both closed with the Sharp damage looking quite serious to my non-professional eyes. However, neither have been stickered and I’d be surprised to find that either of them were considered earthquake-prone. If that is the case, then is the current evaluation exercise based on good principles? Which is a useful question to ask, since we’re planning to spend billions of dollars on the results of the evaluations. And in the process pushing a lot of apartment owners into a position of negative equity or bankruptcy.

Bob the Builder
25 - 07 - 13

Davep – I haven’t had a look at the NEC building yet, but have had a good squiz at the Sharp Centre in Taranaki St, and might venture to make some commentary to allay your fears. The Sharp building is a concrete frame building, clad with external precast concrete vertical panels, over all the upper floors, but not on the ground floor. My assumption is that the precast panels are not structural, and so it does not matter whether they move, crack, or whatever, as long as they do not cascade into the street. What matters is, of course, the structural integrity of the columns and beams. Luckily, or perhaps I should say fortuitously, there is no sign of structural cracking in either beams or columns. There are other small cracks on the junction between the precast concrete panels and the concrete frame, which are to be expected. The building, therefore, is safe, and certainly not earthquake prone from that evidence. Hence no red or yellow placard.

What has cracked, however, is the concrete block surface of the non-structural infill structures on the ground floor, such as the enclosure with the massive surface cracked spalled concrete exposed on the south side, and the minor cracking on the west side. My guess on this is that the concrete frame of the building has moved, and that the concrete block ground floor structures have not. They are short (one story), stiff (concrete block), and brittle (hence the breaking). My guess is that the two structures have moved differently to each other, and the small, brittle structure of the ground floor has lost out in the battle with the taller, stronger, more flexible concrete frame. No need to panic.

Jason
1 - 08 - 13

This is a semantic argument more than anything else. What is your threshold for labelling damage “serious”? There were visible cracks in buildings, broken glass and other debris in the street, power cuts, and part of the city fell into the harbour. The capital city was essentially shut down for a day, and there are still buildings unoccupied due to damage.

The language perhaps tended toward sensation, but that’s a feature of NZ news media more than a reaction to this particular event. See also “We now cross live to someone standing in Wellington to repeat verbatim everything we said in the lede”; “Backyards devastated by slip”; et al.