Well in the 1980s there was Definetly an uptick of quakes both N. Cal and Socal. It seemed like from 1980 to 1989 you were guaranteed at least one 5 a year in the Bay Area. Esp. after 1985. In 1988 and 1989 there seemed to be a huge increase in 5s on the Calaveras Fault. One in June of 1988, Spring of 1989 (I belive that one shattered windows at the control tower at Reid Hillview) 1986 Mt. Lewis, the 2 5+ Preshocks in the Santa Cruz Mountains...so yeah in regards to what Don just said, very little north of these areas. But it is interesting to note after Loma Prieta the Bay Area did indeed go into some kind of seismic shadow again like it did after 06.

Same in LA, from 1987 to to 1994 they had Upland, Sierra Madre, Whittier, Landers, Big Bear, Malibu. Aside from HEctor Mine, one could argue Northridge put a shadow on the area as well.

Its just so frustrating. I wish we had the computer technology we have today only 2000 years ago so that we'd have that history. Just like Don pulls those catalogs for the past 10 years for a given location, could you imagine if he could pull ever single 4+, 5+ or 6+ quake for the past 2000 years? I think for certain we'd be able to diagnose the situation exactly.