[Cob] How wide should a cob wall be in earthquake zones?

[Amanda Peck]

By now there may be a couple of cob shake tests--the one I know of was in 
BC.  It passed, with some damage, although IIRC the shake machine couldn't 
be turned off, so it got more shaking than planned.

Most of the people I know who are doing machine made cob are using a tiller 
or a skid steer loader to do the mixing.  Neither mortar mixers nor concrete 
mixers will do the whole job.  Although you might be able to break up your 
clay and add sand with either.

People who are building slip-form concrete houses do the equivalent of 
small-batch concrete footings or foundations.  It can be done.  If I were 
doing concrete footings, though, it sure would be nice to just get it done.  
Then fuss with my stone or urbanite foundation and stemwall that people will 
see.

.................
David on Whidbey Island wrote (snipped):

I'm thinking of buying a cement mixer then puting up a small shed to protect
it and other tools from the elements before I begin the project. Any
sugestions on which type to purchase? I would like to do most of the cob
mixing in the cement mixer along with mixing clay plasters later in the
project. Eventually I woiuld like to surround the whole structure in a cob
wall to make a nice cozy courtyard with the rear sides of the building being
connected to the courtyard wall. Think of an african Kraal and you may be
able to picture about what I want to do.

Question though, can a concrete footing be poured in phases or does it need
to be poured all at once? I would like to do this myself but could hire a
cement truck if necesary to come to the property.