Petra,

New York quakes and others far from plate boundaries may be quite different than California quakes-here may not be a steady loading of stress-there is high stress already-close to failure. Then, something comes along to set it off. According to Nano Seeber (at a talk at Lamont 1/2 year ago), half the time it is people who set it off-reservoirs, quarries, fluid injection. I'll let you know if he has anything to say about this one.
I'm just back from not checking email for 10 or 11 days-was at AGU/EGS
Chris

But for New York, it is most likely just a routine quake, on a fault that has a little stress and is just moving along as faults normally do.