Interesting liquefaction video:

http://www.youtube.com/watch?v=tvYKcCS_J7Y

[YOUTUBE]tvYKcCS_J7Y[/YOUTUBE]

And for those of you who, like myself, had never heard the term before the earthquakes this is what it means:

Soil liquefaction describes a phenomenon whereby a soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other rapid loading (force), causing it to behave like a liquid.

The phenomenon is most often observed in loose sandy soils.
Further description here:

http://en.wikipedia.org/wiki/Soil_liquefaction