
I have always considered "early" Jewish families in the Bay Area to be those who came here well --> before <-- the large wave of "Pogrom Immigration," with particular emphasis on Gold Rush immigrants.
Using the marker "pre-Earthquake" cuts that too close, in my opinion.
For instance, the Haas family funded and sponsored Russian Jews to come and have chicken farms in Petaluma (in the Bay Area) as part of their charitable activities -- but the Chicken farmers were Pogrom refugees in the second wave of immigration, not "early families" in the first wave. (See the book "Comrades and Chicken Ranchers" by Kenneth L. Kann (Cornell University Press, 1993).
I divide California Jewish immigration waves into four groups, approximately, based on what drew them or what forced them out of where they were:
Gold Rush (mostly German)
Pogrom refugees (mostly Eastern and Russian)
Reich Refugees (mostly German)
Soviet Collapse (mostly Russian/Ukranian; some via Israel)
Each group had its own style, its own alternative (non-Hebrew, non-Yiddish) language(s), its own community institutions, and its own ways of adjusting and assimilating.
To me, blurring the date-line to "pre-Earthquake" mingles Pogrom refugees with Gold Rush entrepreneurs from Germany. They are really quite different ... to me, at least.
I grew up here in the Bay Area and my mother was a "Hitler emigre" from an old Nuremberg family. As she pointed out, we were related through close cousin-hood and shared surnames to quite a few of the Gold Rush era San Francisco Jewish families, but we were not related by shared surnames to the Pogrom-era Jewish families.
I am not trying to start an argument here, just adding a bit of thought to the discussion. Take it for what you will.
Post Script to the above: I did not intend to exclude Sephardim -- but aside from a few who came with the Spanish conquerors, the Sephardic presence in the Bay Area seems to date primarily to the 20th century, and to include primarily Reich Refugees from the Spanish Civil War. See http://www.magaindavid.com/history.html