Liquid sand

My most recent obsession is emergency preparedness. Not on the FEMA scale, but on an every day, basic intelligence scale. Little things like: when there is an emergency, never go UP stairs, but instead always go down and towards the nearest ground exit. Or when some one yells "Heads up!," don't actually look up (which then lets your face be the target) but instead stand still and preferably find yourself skinny at that moment.

Anyways, when I saw this video about sand in a liquid-like state, as often happens during earthquakes, I was fascinated.
http://www.dump.com/2011/02/28/christchurch-earthquake-showing-how-the-sand-liquefies-with-vibration-video/

So I followed it up with some good old wikipedia research: http://en.wikipedia.org/wiki/Soil_liquefaction.

Here are some more pictures of what liquefied sand looks like/does. http://www.google.com/images?um=1&hl=en&safe=off&biw=1251&bih=683&tbs=isch:1&sa=1&q=liquification+sand&aq=f&aqi=&aql=f&oq=

Long story short: don't trust sand. And definitely don't build a bloody city on it.
Oh and last but certainly not least: levees and dams are still an embarrassingly insufficient idea to protect populated areas from natural "disasters." Mother nature is way smarter than we are.