Hi Todd, we have not heard from you in a while; keep posting. While I don't know northern California faults very well, as far as I know Sacramento does not have faults close to it that slip >1 mm/yr. But, San Diego does, with the Newport-Inglewood fault becoming the Rose Canyon fault and coming right onshore into the city. Tom Rockwell trenched it and it is right-lateral at 2 mm/yr in the last few thousand years (offset dated channel, 3D network of trenches. The math says if that fault were to have 1 m of slip in an average earthquake, at 2 mm/yr it could slip in any one place every 500 years (or if 2 m of slip, every 1000 years). That might not seem that hazardous, but the same fault, called the Newport-Inglewood, has a similar slip rate propbably, and made the deadly 1933 M6.6 (?).

By coincidence "Heartland U" student Masters student Jon B. and I yesterday completed 3D representations of a system of faults just offshore of San Diego that intersect in cross section. The eastern one, the Descanso fault, shallow trace is only 5 km offshore of the San Diego coast, but dips away from the coast, towards the SW. Other faults, part of the Coronado Bank system, dip towards the coast but their shallow parts are much farther offshore. The low-frequency sub-bottom acoustic data that we are using does not have the resolution to detect whather these faults offset the youngest post-last glacial maximum sediments, But, high resolution seafloor multibeam bathymetry images en-echelon fault patterns.

We have more work to do to try and get at least a slip type on these faults.

Chris