nin wrote on Jul 27, 2015, 15:34:
This is what we get for fracking.
Take stuff out of the ground, ground goes down, although usually it happens slowly enough to have microquakes instead of stuff you can feel (that goes for fault movement, too, for that matter).
Sinkholes in Florida happen for the same reason (limestone caves that used to filled with water aren't anymore, and humans construct large buildings on top of the empty caves) but closer to the surface.
Source: M.S. in Geophysics with an emphasis in Earthquake Seismology