Goedjn wrote:

Is your objective to prevent quake-damage to the wall, or
just to keep it from falling on anyone when it is damaged?
If its regualr concrete-masonry units, then yes, you
can saw (or bash) the top row off and insert vertical rod,
which should keep it from spitting out individual blocks
on peoples heads.

We are in a pretty benign area so, the purpose of the wall is to
separate our yard from the people next door.

I have thought of doing as you say - taking off the top row, adding
rebar and cement to make the wall solid. When 'the big one' comes, I
reckon that means the whole wall falls down rather than individual
chunks?