Do you need to put as much energy into an already-loaded system as will be released, though? Compare the energy released by a stack of blocks falling to the amount it takes to topple it. I think it's unlikely we will ever be able to trigger quakes intentionally, but there's some implication fracking to extract natural gas [1] is causing seismic activity, for example.

1: http://time.com/84225/fracking-and-earthquake-link/