It is so hard for me to believe that this is possible.
I think it might well be possible if you choose your fault or volcano carefully and put the right amount of energy at a critical point. But the "right amount" of energy would be huge!! A large nuclear blast - possibly a chain of them for a large earthquake - would probably be necessary to trigger anything "interesting." You'd probably also have to explode it well underground - a surface explosion is unlikely to do anything. A good-sized meteor would also suffice but would be harder to arrange. :-) But how do you compute what's enough energy and how do you identify a critical structure? Seismologists have studied this for decades and it's still not a very exact science.
If you're trying to do something like that it's probably a better bet to look for unstable soil regions or a large dam that you might blow up - those could be quite nasty without taking on something as hard as what you describe. Personally I think the idea of creating large-scale earthquakes like that is just wishful thinking - the logistical problems are huge, most especially if you need to keep your preparations secret.
Not true. http://www.pbs.org/tesla/ins/index.html
Even a Niagara Lab: http://www.pbs.org/tesla/ins/niagara.html
Now do a search on Tesla + earthquakes in Google.