When I was still in SoCal, there were a few 'small' quakes that I felt quite strongly. There are many factors but two in particular I think make a big difference. Soil conditions are obvious, but also the way in which the fault breaks seems to have a 'focusing' effect on the direction of the quake waves. San Simeon is a perfect example in that it was felt south to the border, but not much north than the Bay Area.

Brian