posted on Jul, 30 2012 @ 12:42 AM
Sorry OP, but no, nada, never gonna happen.
The mineral composition of the continental plates is composed of significantly lighter weight material, which causes them to float above the deeper
rock (who's composition is of highly Fe rich material).
The mantle isn't some bubbly sea of molten lava: It's largely composed of viscous, slow-moving rock. Think silly putty or thick taffy, compressed to
insane pressures. And that's deeper towards the core. Near the crust, there is an additional solid layer called the lithosphere
A void can't exist under the crust. Gravity pulls everything equally to the center of the sphere...the pressures acting upon the planet would
backfill any void before it could happen!
Even if a plate could sink, the sheer size and materials involved would require that the event take millions of years to occur. Not anything to lose
sleep over, I'd safely say.
I wonder if flood insurance would cover lava flooding?