If the foundation of your home is visibly brick, old clay block, or unreinforced concrete block this would be considered an unreinforced masonry foundation.
Brick and unreinforced masonry do not have lateral strength because there is nothing connecting the wall together (ie. there is no rebar). At Earthquake Tech, we say “Every Brick Is An Island.” Hence, during an earthquake, the foundation will collapse. It is more than likely that your 100-year-old foundation is not going to withstand an earthquake; emergency professionals call these types of homes “standing rubble.”
A home with a brick foundation will fail unless it is reinforced by an SR Wall or taken out and replaced with a new concrete foundation.