* Human-made earthquakes
I've only got this far in the thread right now, so if this has already been said, sorry.
Man made earthquakes aren't that far fetched. The first example being the massive earthquake bombs of WWII, like the tallboy. They didn't have the power of a real earthquake, but they did shake the ground pretty good in a small area.
The second example, which is more recent, is unintentional side-effects. Anyone remembers the big story of the notably strong earthquakes in Oklahoma a couple years back? The think is, Oklahoma almost never has an earthquake that can be felt in the slightest, much less one the could shake a picture off the wall. It was freaky as hell for all of us here, as most around here have never felt an earthquake. The days after people were wondering what could of caused suck an unusual event. Some experts apparently thought it might be linked to the fact that oil drilling is a big thing in Oklahoma. How big? There is a working oil pump on the front lawn of the state capital building. Someone proposed that the extraction of oil might have destabilized the ground or something, and some said it might be fracking in particular. I'm not a geologist, so I can't speak to just how much truth there might be in these ideas, but it's not at all unbelievable.