The Parkfield region is very sparsely populated. A disruption on this segment of the San Andreas Fault, comparable to past similarly-sized events, would probab

The Parkfield region is very sparsely populated. A disruption on this segment of the San Andreas Fault, comparable to past similarly-sized events, would probably NOT have significant effects in major populated regions of either the San Francisco Bay Area (San Jose is 128 miles north) or Southern California (Santa Barbara, which is the northernmost extant of the SoCal conurbanation is 110 miles south). That's roughly 120 and 180 km respectively. Earthquakes' effects are most strongly felt immediately around the epicenter, and diminishes with the square of the distance. The San Andreas Fault, being a strike-slip fault (plates moving laterally against one another) and lying principally inland has very low tsunami risk. Tsunami are most associated with superthrust faults, in which one plate rides up over another, and energy is release with a strong vertical displacement, as with the 2011 Tohoku and 2004 Indian Ocean earthquakes.