The sand to your doom.

[Rawr]

I heard during an earthquake, if you just happen to be near sand,
like say the beach, you'll be sucked underneath.
but there's been lots of earthquakes in the past
how come i've never heard of anyone on the news getting sucked under the sand during one?

[ms.peachy]

I think you must be referring to the phenomenon of liquefaction (http://earthquake.usgs.gov/learning/glossary.php?termID=111&alpha=L), which does occur in some earthquakes. It's not so much that anything (or anyone) gets "sucked under", it's more that the saturated soil behaves more as a liquid than as a solid when it's experiencing tremor activity, so it can't support the weight from above. It generally occurs in sort of small pockets in open land; it's more of a danger under buildings where the substrate is sandy soil or landfill, because there's all this weight from the building pressing down (gravity), the pressure of which, combined with the tremor activity, accelerates the liquefaction process.

Here's a demonstration I've used with students before (http://www.exploratorium.edu/faultline/activities/liquefaction_activity.html) that is good for illustrating how it happens.

[jabumbo]

watching a soil collapse like that can be simply amazing.


nobody really thinks of soil being something that can just buckle under the pressure, but it is certainly maddening to try and figure out. but then again, its about 20 time worse trying to fix it when it does happen