As some of you Bay area type may have felt...early this morning your time there was a M3.4 quake with location and focal mechanism consistent with right-lateral slip on Hayward fault. Less than 2 hours before this, there was a M4.1 to the nrotheast...says 14 km NE of Napa...one of whose 2 possible planes was right-lateral on N-S fault...

The 4.1 should probably be too small to trigger a 3.4 60 km away by static stress....but I doubt they are a coincidence...so, how does one trigger the other? The P and S waves of the first tickled the second, starting some small-scale slips that took a little while to cascade to an earthquake?
Chris