QI first heard of quick clay when I was searching for something for this post!  I know of quicksand, of course, but quick clay seems to be something the same but different.

Wikipedia says: Quick clay is only found in the northern countries such as RussiaCanadaAlaska in the U.S., NorwaySweden, and Finland, which were glaciated during the Pleistocene epoch.

So most of this post is not really about quick clay itself, but soil liquefaction generally.

I remember watching a documentary, I think it was one of those historical travel searches for a famous lost city, possibly by Michael Wood or John Romer.  They were looking for a city well-known in biblical times, that had simply disappeared without trace.  By working from clues in the Bible and other ancient manuscripts, they tracked this city down to the edge of a lake in Jordan, not too far from Petra.  But could they find any sign of it, any ruins or old foundations?  They couldn’t.

Then the geologists identified something in the surrounding land that indicated there had been a massive earthquake, which had caused a mudslide of phenomenal proportions.  The documentary showed a laboratory test in which rockforms of the surrounding area were subject to shaking, simulating the earthquake.  The most extraordinary liquefaction of the rock occurred, making anything on the surface simply sink.  It looked like the earth had turned to water, and then solidified once the shaking subsided.

The conclusion was that this had been the fate of this city.

So, when I see ‘quick clay’ described as clay particles which can act as a liquid, in the same way as a quicksand, I think of this lost city.

The sad fact is that the people of New Zealand, and especially of Christchurch, will be all too familiar with this description.  Earthquakes are not just about the ground opening up beneath our feet, they are also about liquefaction of the ground itself.  Almost as bad as Pyroclastic flow.

Quick clay landslide picture from ngu.no (National Geology Survey of Norway)

If you’d like a chance to win one of my ebooks, nip over to my guinea pigs’ blog George’s Guinea Pig World today (or any time to the end of April).

Quick clay
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24 thoughts on “Quick clay

    • 20 April, 2015 at 12:19 pm

      Thanks, Suzanne! It’s doing me good, too 🙂

  • 20 April, 2015 at 2:29 pm

    I think liquefaction is what caused so much damage in some parts of San Francisco in1989. The parts built on fill responded badly.

    • 20 April, 2015 at 6:20 pm

      almost certainly….

    • 20 April, 2015 at 6:23 pm

      PS I was in SF in 89, but for the first one, August, I missed the main one by a couple of months. Actually I slept through the one I was there for… strange, since I woke up for our 4.2 one here in about 2009. I think it was about that.

      • 21 April, 2015 at 3:44 pm

        I’ve always missed the big ones, but have been through enough not-quite-small quakes to have practice diving for doorways and under things!

    • 20 April, 2015 at 9:26 pm

      Yes indeedy.

    • 20 April, 2015 at 9:26 pm

      Me too!

  • 20 April, 2015 at 10:06 pm

    Never heard of quick clay but it sounds scary. Imagine a city being swallowed up!

    • 21 April, 2015 at 5:00 pm


  • 20 April, 2015 at 10:11 pm

    We live on what we call blue slipper clay which sounds somewhat the same. The old houses were small light and built on rafts which tipped and tilted but the new replacements are on very deep foundations and static. It will be interesting to see if they last as long as the originals.
    Very interesting article. Thankyou.
    Anne at http://www,authorsupport.net

    • 21 April, 2015 at 5:02 pm

      Interesting what happens when they change construction practices; I know there’s been a resurgence of interest in deep piled but ‘rafted’ houses for earthquake areas like the old Japanese buildings.

  • 20 April, 2015 at 11:13 pm

    I am so very much adding this to my list of “cool and horrifying things about the natural world” 🙂

    • 21 April, 2015 at 5:03 pm

      Very good list!

  • 21 April, 2015 at 1:06 am

    Whenever I hear about a new way the world can just up and kill you with little to no warning, I start searching for places to live with the least natural disasters. Quick clay is a term I’d never heard before, but I did know about soil liquefaction, and how it has destroyed cities in the past.


    • 21 April, 2015 at 5:04 pm

      I’m glad to live in a relatively safe area – until the Government allows those fracking b**** to undermine our homes >:)

      • 21 April, 2015 at 11:42 pm

        Oh no, you live in a fracking sensitive area? 🙁

        • 28 April, 2015 at 8:42 pm

          Hopefully not, but these people will go anyway to ‘test’. WordPress obviously considers fracking to be a swearword – it sent your comment to spam!

          • 28 April, 2015 at 10:47 pm

            It almost should be a swear word! 😛

  • 21 April, 2015 at 1:39 am

    That was so fascinating! I had no idea rock could do that. That was a fantastic pick for Q 🙂

    • 21 April, 2015 at 5:07 pm

      Thanks, IL – nice to see you!

  • 17 May, 2015 at 12:45 pm

    Hi Jemima – yes quicksand is pretty nasty … but your Quick Clay sounds positively ghastly … I wonder if quick clay could be a factor in the sink holes that keep appearing in parts of England … cheers Hilary

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