Christchurch Quake

February 23, 2011 at 11:48 am (By Randy)

Administrator’s note:  I’m front-paging this post for the time being, because its comments section has unexpectedly become such an extraordinary source of direct reporting from Christchurch.

It appears that most of those killed by the devastating earthquake that hit Christchurch, New Zealand, were inside modern structures built to strict standards. The latest reports are that none of the 100 people believed to be inside the CTV building when it collapsed during the quake survived.

The CTV building pre-quake:

The remains of the CTV building after the quake:

I can’t find a pre-quake photo of the Pyne Gould Guinness building, but here is what is left of it after the quake:

The Hotel Grand Chancellor has apparently shifted off its under-pinnings and is now in danger of collapse:

[UPDATE:] Damage to Hotel Grand Chancellor apparent in photo found on internet below. If the building doesn’t collapse on its own, it will have to be demolished.

[UPDATE 2:] Check out the Highly Allocthonous blog, where geologist Chris Rowan, a specialist in tectonics,  provides informed discussion, maps, graphs,  photos and videos from a variety of sources  about both the February and September Christchurch earthquakes. (Don’t overlook his first post about the February earthquake.) The links provided are outstanding.


  1. chasrmartin said,

    The strange thing is that this was a 6.3 quake. I’ve sat through 6.3 quakes in california, and the reported damage was broken dishes and occasional foundation cracks.

  2. Randy said,

    True, Charlie. I’ve read mention that the relative shallowness of the quake contributed to the severity of the result. Apparently, the stronger September quake in the same area was much deeper.

  3. amba12 said,

    Right, it’s not just the strength but how the waves propagate. If they traveled sharply up and down . . .

  4. amba12 said,

    And how many people out here were thinking of NZ as a magical refuge from all troubles?

  5. Randy said,

    And how many people out here were thinking of NZ as a magical refuge from all troubles?

    Don’t know about here, but most of those I know of quit singing its praises when it was tagged as a major contributor of methane to the atmosphere. ;-)

  6. mockturtle said,

    We often have quakes of that magnitude around here with no damage. It’s horrifying that so many were killed. I haven’t read any of the articles about the CTV building but it will be interesting to see a study of the structural design in view of the collapse, like the analysis that was done on the World Trade Center after 9/11.

  7. Peter Hoh said,

    A dozen or more years ago (shoot, maybe it was 20-plus) I recall overhearing someone going on about how great NZ was, saying that it was like the 1950s in the U.S.

    As to the earthquake producing such damage, most likely, somewhere along the line, a contractor used inferior materials in building these structures. The long shot possibility, however, is that this earthquake produced stresses that engineers had not considered when designing these buildings.

    We had an exhibit about buildings at the Science Museum of Minnesota a few years back. (Raise the Roof, currently showing in Vermont.) One of the displays showed how different vibration frequencies affect buildings. There were two flimsy buildings, one short and one tall. When the underlying material was vibrated at one frequency, the short building collapsed and the tall building barely swayed. At another frequency, the tall building shook violently before collapsing, while the short building barely swayed.

  8. louisemowder said,

    BBC reports:

    “Among the worst hit buildings was the home of Canterbury Television (CTV) – at least 15 staff members are still missing but rescue work was called off as officials said there were no signs of life.

    The building also housed the King’s Education language school, attended mostly by students from Asia. Kento Okuda, a 19-year-old from Japan, had his leg cut off to allow his rescue.

    “As we were eating lunch, there was a major shaking, and suddenly the floor fell,” he told Japan’s Asahi Shimbun newspaper. “Everyone around me was saying things like ‘It hurts’ as they fell downward,” he said.
    “And then I realised I was in total darkness, with my right leg pinned by something so I couldn’t move.”

    “At the Pyne Gould Guinness building, cheers were heard on Wednesday as office worker Ann Bodkin was pulled out alive after being trapped for more than 24 hours, and reunited with her waiting husband.”

    As the quaking started, she got under her desk. After looking at the remains of the building, it’s amazing anyone got out alive.

  9. michael reynolds said,

    I was in Christchurch just a couple months ago and they were still not over the earlier quake. People would pull me aside to show me their pictures. The first round was evidently a bit traumatizing, this must be hitting them very hard.

    I stayed at the hotel right where the church tower fell. I recall being irritated because as I was unloading my car the church bells were going crazy.

  10. Nathan Banks said,

    to chasrmartin this was only a 6.3 but it was very very shallow and was equivelent to a 8.6 i was in the quake at school in christscollege and that fell down

  11. Randy said,

    Sorry to hear about your school, Nathan. Glad to read that all your classmates are accounted for and safe.

  12. Kim said,

    The effect a earthquake has on a structure is completely dependent on the specific structure (i.e. the natural frequencies of the structure itself) and the frequency content of the earthquake and the associated accelerations. Even though this earthquake was “only” magnitude 6.3 this actually says very little about the devastating effect it can have. It all depends on as someone said previously the wave propagation and also most importantly the depth. This most recent earthquake was only 5km down and only something like 10 km away from the city while the previous 7.1 earthquake was 33 km down and further away hence the little effect on the city.

  13. mm said,

    Chasrmartin , you probably felt a distant 6.3 which was much deeper than this earthquake. This quake was only three miles from the center of Christchurch and 2.5 miles deep. That’s very shallow and therefore focus all its energy toward the city.

    1989 7.0 Loma Prieta earthquake which shook the San Francisco Bay area was 11 miles deep and the 1994 Northridge earthquake in LA was 11.8 miles in depth. Much deeper than 2.5 miles.

  14. Paul said,

    I work in the government building opposite the CTV building. From my window on the third floor I had a great view of the building. I wasn’t at work that day, but my wife was. She works on the 7th floor of my building. Disasters come in many forms, but this is wholesale destruction. Buildings, roads, power lines, sewerage, water supplies everything is gone. Petrol is hard to find. Water is out everywhere.

    The worst thing is the constant aftershocks. Two of them while I have typed this comment.

  15. Randy said,

    Michael: If you are still around, what were you doing in Christchurch? Book tour? IIRC, I was scheduled to be there tomorrow (cruise around NZ and Australia) but had to cancel the trip. Christcurch is one of the places I was really looking forward to, having missed it on my one and only visit to beautiful New Zealand in the mid-90’s.

  16. Phil said,

    I live in Wellington NZ but am from the south Island and have many family and friends in Christchurch luckily all still alive but a lot of them now have homes that are a wreck if they can even get back to them at all.
    What you probably are not hearing over in the states is the fact that the whole of the country is helping out as much as they can and people from the community are helping out others in more need. Such as the group of 80,000 Canterbury University students that are going round the suburbs cleaning up the mud off the streets and doing there part while students from the Dunedin University are oraganising food packs for the Canterbury students to be sent to christchurch. Thats just one example of how NZ is sticking together through this and shows what a great country it was and always will be!

  17. Randy said,

    Thanks for sharing that information, Phil! As you say most of the reporting about recovery efforts is relatively cursory. Kudos to the students.

    Thats just one example of how NZ is sticking together through this and shows what a great country it was and always will be!

    Indeed! As anyone who has visited or had the pleasure of meeting Kiwis elsewhere knows, you have a magnificent national spirit.

  18. Geoff said,

    To clarify the type of movement involved, please see the quote below. There has also been speculation that the shock wave may have reflected back up off deeper harder volcanic rock to combine and interfere with the primary shock waves, so it seems to have been a unique and complex event far exceeding the intensity usually associated with magnitude 6.3. I read elsewhere that the building code was designed to withstand magnitude 8 along the main alpine fault line. Until last year, nobody knew about the fault line that is currently active (it may indeed be a new one). The stress the buildings experienced in this 6.3, so close and shallow, was greater than that expected from an 8 on the alpine fault.

    ‘The quake was a “strike-slip event with oblique motion”, meaning the earth moved mostly side-to-side but occasionally up-and-down. The vertical acceleration of the earth, at 1.9 times the acceleration of gravity, was far greater than the sideways movement. “Anything you put at nearly 2g – it’s like lifting a building and dropping it to the ground.” Professor Malin said the simultaneous vertical and horizontal seismic shifts made it almost impossible for buildings to survive. “It’s a blow from below that compresses things up, then a shove sideways, and very little can withstand that.”

  19. Geoff said,

    To continue with quotes from experts:
    “The ground motion in Christchurch was over what we expect for a 1000-year return period,” he said. “We design for a 475-year return period.”

    This means the ground shaking from Tuesday’s magnitude 6.3 quake was even more violent than Christchurch can expect from a magnitude 8 jolt on the Alpine Fault, which is expected every 300 to 400 years and was regarded as the test that buildings had to be designed for. The fault last moved 290 years ago.

    Dr Ma said the fault that shook the city this week had not been identified as a major risk before.

    Early investigations have suggested that the shallow earthquake was an aftershock of the September quake in Darfield, but did not come from the same faultline.

    GNS Science natural hazards platform manager Kelvin Barryman said tests indicated it occurred on a “blind” or unknown fault, which runs east to west 1km north of Lyttelton.

    This meant that – like the Darfield fault that had lain dormant for at least 16,000 years – the Lyttelton faultline had been accumulating extreme pressure over centuries, before collapsing catastrophically.

    Experts said the enormous aftershock was statistically unusual. Generally aftershocks get smaller and less frequent as months go by.

  20. Geoff said,

    John Clague, an expert in natural hazards at Simon Fraser University in British Columbia, said it was unclear what caused such serious damage to modern buildings, but said the answer could be the “liquefaction” of the ground when the shaking began.

    “Liquefaction is a huge problem in Christchurch because the city is built on an alluvial plain, on sediments that are vulnerable to liquefaction,” Clague said. “When shaken, these sediments transform into a liquid, causing irregular settlement of the ground, which is extremely damaging to buildings and buried structures, like water lines.”

    Because the ground loses its rigidity, buildings can be shaken far more violently.

  21. Paul said,

    Can we get some links to the information being quoted about the particular nature of the shockwaves?

  22. Randy said,

    Paul: Here’s a link to the Guardian article from which Geoff was quoting in his last post.

    Geoff: Thanks for posting the quotes! Confirmed what I’d heard about NZ codes before this last devastating event. An 8.0 standard seems pretty “strict” to me as, but I’m not an engineer.

    EDIT: Paul, the second of Geoff’s posts apparently first appeared in NZ Herald on the 24th, but I found a copy posted to the Association of Consulting Engineers New Zealand website.

  23. Randy said,

    EDIT: See new update at bottom of original post for more detailed information.

  24. Geoff said,

    In response to the question about my sources, I don’t have all of them, but the second part of my first message can be found in the second indented (grey) quote in this article:

    Here is another interesting article quotes Geologist Hamish Campbell; it gives details of the “wave reflection hypothesis, stating that some buildings may have been hit by a “rogue wave” and mentions that the quake “reached 9 on the Modified Mercalli intensity scale”:

    From the geological point of view, this site gives detailed maps, etc., and will no doubt be updated.

    Here is another great article, with lots of links to more information/opinions:

    Here is a page of quotes related to this quake and building codes from Canadian and Australian specialists:

    For those who want to follow the ongoing history of quakes in the area, here is a constantly updated interactive quake map for the region showing all events since last September:

    With the associated daily energy release chart here:

    The last two sites are thanks to my niece in Christchurch, who is OK, along with my other relatives there, as far as I know, but she lost two friends in the quake, so it hits close to home. Also, my brother’s house is on a steep slope supported by 15-foot poles that have cracked. I would be very nervous staying there, but they are for now. So far 1 in 6 residential houses will have to be demolished, along with at least half of the central business district. Beyond the trials of day-to-day life there must be much uncertainty about the future. Who knows if their employers will ever start up business again, and on what scale?

    My niece (a university student) told me that after the previous quake (Sept. 2010) some people got used to the aftershocks, but others couldn’t – for them, every shake brought on the panic of the original event. Many students at Canterbury university are from other parts of New Zealand. One of her friends couldn’t take the aftershocks and dropped out to go home. That was last time, when there were no deaths. This time, I can imagine there are many more people who just will not be able to live with the strain and uncertainty – and some may never be able to come back without triggering painful memories and fears. Anyway, I hope the shaking continues to abate with no more nasty surprises in a city that was (and will again be) so peaceful and beautiful.

  25. Paul said,

    Thanks Geoff.

    Official news is saying that 40% of CBD (Central Business District) buildings will need to be demolished.

    We just don’t know yet how much will need to be taken down. The stronger aftershocks are just damaging broken buildings further and it is going to take a few years to get everything down. A lot of buildings were still being demolished after the September quake when this aftershock hit.

  26. Randy said,

    Paul & Geoff: Thank you both for dropping in here to exchange information. As with Phil’s contribution above, am learning a lot that isn’t easily found elsewhere. There are a lot of people from all over the world clicking through to this post and we can tell many are following the links provided.

    The figures you are quoting, 40-50% of central Christchurch and 1 out of 6 houses may end up being condemned, aren’t so much frightening as moving. Lives and livelihoods disrupted and destroyed in a moment. Having grown up in Southern California, lived through a couple of major quakes, and reassured by strict earthquake standards, I’ve been relatively sanguine about what might happen should a truly big one occur. What happened, and is happening, in Christchurch has changed that outlook.

  27. Paul Mannering said,

    Keep in mind that even if 1 in 6 houses do end up condemmed, it is only in certain areas of the city.

    Particularly on the eastern suburbs (the coastline) and along the cliff and beach suburbs of Sumner and Red Cliffs.

    Because the eastern suburbs are both closer to the epicenter AND built on very sandy soil (it’s nearer to the beach) they suffered the worst damage. Eastern suburbs are also older, and much lower socio-economic demographically. Ironically though Sumner and Red Cliffs (south east) are the Christchurch equivalent of Beverley Hills – $1 million dollar homes commanding amazing views from the cliff top. Now ruined.

  28. Paul said,

    Other parts of town are not so badly damaged. Satellite towns are completely fine and are organising aid for Christchurch. The CBD had the highest buildings and a lot of them were historical brick buildings. Strengthened to withstand earthquakes but nothing like this.

  29. wj said,

    Geoff, you mention the problem of liquefaction, because Christchurch is on an alluvial plain. San Francisco has a similar problem — except that its downtown is built on fill generated in the late 1800s by throwing everything from dirt to old wooden beams into the mudflats. The water table is, at most, a dozen feet below the surface.

    The way they have approached the problem is essentially to float the multi-story buildings. Skyscrapers are built with massive weights in their subbasements, which lowers their center of gravity below ground level. When the earth shakes, and the ground turns to soup, the buildings sway and then return to vertical like one of the toys I remember as a child — in fact, I believe that was the inspiration for the design.

  30. Geoff said,

    Speaking of water tables, I have never heard of a house in Christchurch having a basement, presumably at least partly because of ground water. As a child, I found that if I dug a hole about 2-feet deep in the clayey soil water would flow in endlessly as I removed it (this was in the fairly central suburb of Richmond, not in the sandy East). So there is water close to the surface most of the year.
    My “wells” would dry up in the summer though (when there is usually a drought and unwatered lawns die), so I suspect the liquefaction problem might have been a lot worse if the quake had occurred at a more water-logged time of the year (February is late Summer). I imagine that would have intensified the surface liquefaction problem for roads, underground piping, and private houses.

  31. michael reynolds said,


    I was there on book tour. I visited three schools. Two of them appear to have suffered serious damage but their websites are up, and while they are closed, they appear to be making progress toward re-opening.

    The third school, Shirley School for Boys seems to have been hit harder. Their site is down and all they have is a statement that begins: “The school is closed until further notice. Please stay home, look after yourselves and your family. Do not come to school. There is damage.”

    Christchurch is a low-key sort of place. Driving around the neighborhoods you might think you were in a small Northern California town. The downton was small, dominated by the church, with a few buildings that as I recall were under 10 stories. Lot’s of tourist shops, a few restaurants, not a lot of activity.

    They were still dealing with the much milder earlier quake and did not seem to have acquired the sort of studied indifference a Californian would have. But of course no one would have much sang froid with this disaster. This is the kind of destruction you don’t expect to see in a 1st world country, and a good reminder to us here in CA that all the quake-proofing in the world won’t save you if you get the wrong quake in the wrong place.

  32. Geoff said,

    Surprising liquefaction headline: “Liquefaction plays part in bringing power” (i.e., it is enabling power poles to be put 3.5 m into the ground rapidly as lineman “work to build a 2.6-kilometre, 66-kilovolt line to supply power to the hardest-hit parts of Christchurch”.
    “… many of the poles were going up in sand, making it almost impossible to dig holes 3.5 metres deep without the sides collapsing. We run high-pressure water under the pole, and the sand turns to jelly and we use the weight of the pole to lower [it] in. So the very problem much of the city was dealing with was also playing a role – on a smaller scale – in rebuilding it.”

    “[they] hope to have power restored to 95 per cent of customers by the end of the week.” – which seems pretty fast – at least people will be able to cook and watch TV.

    Another interesting article “Scientists look into why fault ruptured” (and why there was so much shaking). This quake clearly caught the scientists by surprise, underlining the uncertainty of the situation as new (ancient) fault lines are revealing themselves by a dominio effect. I quote:
    ‘GNS Seismologist Bill Fry said scientists were trying to understand why the fault which ruptured to produce Tuesday’s fatal earthquake had become so stressed. “This certainly wasn’t one of the most stressed areas.”
    When fault lines rupture, the stress is dislocated and spreads out to other faults, which pose varying risks of also splitting and producing more earthquakes.
    However, calculations done after September 4 had not shown the area where last week’s earthquake occurred to be high risk, Dr Fry said.
    Seismologists wanted to understand more about the mechanics of Tuesday’s 6.3 quake and what impact it could have on other faults – particularly those already believed to be very stressed after the Darfield event.
    “A lot of our efforts are going into understanding this problem.”

    Scientists were also working on understanding why Tuesday’s earthquake produced ground shaking or acceleration at 1.88 times the force of gravity, which Dr Fry said was “extremely high” for the magnitude.’

    [The more they understand the better, for the future of Christchurch and the safety of its citizens. Also to help other cities understand and prepare for their own risks.]

  33. Geoff said,

    Wow! Shirley Boys High School (proper name) is my old school!
    There is a photo of it here in a recent article on the effects of this quake on CHCH schools.
    Annoyingly, for those interested in the status of Shirley Boys High School, the caption of the photo has been cut off, so it only states “Shirley Boys High School has been”. Well it looks OK from the air, except for surface flooding and mud, but who knows how the caption should end?

  34. Geoff said,

  35. Geoff said,

    Paying for reconstruction:
    Do other countries have a fund for earthquake expenses? NZ does, fortunately.
    An average of $60 a year is added to home insurance premiums as an “Earthquake Commission (EQC) levy” (in other words there is compulsory additional insurance managed by the government). I don’t know if it is the same rate throughout the country, or adjusted for earthquake risk. The levy will probably now be tripled to refill the coffers to the level of before the Sept. 2010 quake ($6.4 billion) in 9 years (unless there is another major quake somewhere in NZ).
    The estimated cost for rebuilding is “more than $14 billion” and it “could take between 5 and 10 years” (said the Prime Minister).

    Where will it come from: “It was likely the first $3 billion to $4 billion in costs from the two quakes would come from the EQC, $5 billion from reinsurers and at least a further $5 billion from private insurance.”
    Also “In the short-term some businesses will be given help to relocate to other parts of Christchurch. ”
    For more details see:

    By yesterday, $2 million had already been handed out as short-term emergency cash for individuals and families.

  36. Randy said,

    Geoff: AFAIK, here in the United States, federal, state and local governments have no such funds set aside. (Rest assured that someone will correct me if I’m wrong ;-) Although earthquake insurance is available, very few elect it as it is widely believed to be either unnecessary or expensive or both.

    Michael: Your publishers aren’t leaving any stone unturned, are they? “Northern California small town” description is how I remember many of the places I visited. It’s a shame about the schools.

  37. Paul said,

    The recently (in the last ten years) built town of Pegasus, north of Christchurch is also built close to the sea. When towns around them like Kaiapoi and Rangiora suffered major damage in the September quake, Pegasus was unscathed. The reason is that the buildings have (and I do not know the technical term) wire cages filled with rocks in their basements that extend in columns into the ground. When liquefaction occurred the displaced water takes the easiest escape route – which is through these non, weight bearing columns of wire cages filled with loose rock. Water spurted out into the basements but the buildings suffered no subsidence.
    I think the latest quake is going to be a real boon to Pegasus as so many people look for new places to live away from their ruined houses.

  38. Geoff said,

    Good to know about Pegasus, Paul. I hope they apply that technique when rebuilding in Christchurch.

  39. Phil said,

    Heres a link to a New Zealand News site which has heaps of before and after photos

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