The line between Seismic Zone 3 and 4 is west of Tracy. The Seaoc Blue Book
shows it further east. Apparently a new fault was discovered the follows I-5
from Fresno County to San Joaquin County (roughly). the fault is called the
Valley 8 Fault. The State law has provisions to change the Zone limit when
cities do the General Plan updates. One of the cities we do the building
Department administration for (Los Banos) was put into Seismic Zone 4 on
July 1, 1999. When the safety element of the general plan is circulated in
the various State Agencies, Mines and Geology is the State agency that would
change the line. It really doesn't seem fair with areas of Merced County
just outside the Los Banos City limits still being designed to Seismic Zone
3. The Seismic Zone table and the text (areas west of I-5 is the general
gist) in the California Building Code are not consistent with the Zone lines
in Seaoc's Blue Book. The Blue Book (which is more restrictive) has
maintained the lines the same for the last two issues of the Blue Book.
I'll send you the State law sections tomorrow morning when I get to work
regarding/addressing Seismic Zone changes through the State.
----- Original Message -----
From: "SEConsultant" <seconsultant(--nospam--at)earthlink.net>
Sent: Monday, February 07, 2000 5:10 PM
Subject: Seismic Zone for Stockton California?
> I guess I should know this one, but I don't get up North too often. My son
> is moving from Chicago to Stockton California and this is his first move
> into seismic country (other than his summer visits to me in Southern
> I was under the impression that Stockton, Lodi, Livermore and those area's
> were in Zone 4 but he read that it was located in Zone 3.
> Even though there is still some sufficient shaking going on, I'm curious
> where the change from Zone 3 and 4 converge. I would assume it to be the
> foothills of the Sierra's more so than so close to San Jose area.
> Dennis S. Wish, PE
> Structural Engineering Consultant
> (208) 361-5447 E-Fax