This wall collapsed due to improper construction. The wall fell at night during a rainstorm, awaking the homeowners. Water had accumulated behind the wall with no place to escape. The debris was removed and materials set in place for construction. The wall was completed the following day. Note the weep holes for water drainage at the base of the new wall. These were also implemented in other walls on the same property to prevent damage before it could occur.
What it looked like before: