If you look at the video, you'll see how unreinforced masonry collapsed. Block after block of commercial buildings, churches, schools, hospitals and housing crumbled in the force of the quake. As the structures buckled, entire facades fell out and roofs caved in.
In the wake of the 1933 quake, the state took action.
That year, Sacramento Assemblyman Charles Field sponsored legislation requiring all new public school buildings be built to new earthquake resistant standards. No more unreinforced masonry. All school construction plans would have to be approved by a newly-created Office of the State Architect. Several years later additional laws were passed requiring all pre-1933 public school buildings to be strengthened. Yet decades later, many districts lagged behind in retrofitting their schools. As a result, in the 1960s the state required school districts to set up schedules to examine and then modify all of their older school buildings to make them quake resistant, and authorized school boards to sell bonds to finance the work, if necessary. In 1990 the state extended the Field Act to cover private schools and two years later made it optional for charter schools.
As a child in public school I remember going through twice-yearly earthquake drills. Before we crawled under our desks, the teacher would recite a paragraph or two explaining how our 1924 schoolhouse had been reinforced for earthquake resistance, under the state's Field Act. For years I wondered why we youngsters had to listen to this spiel. Years later it dawned on me. The information really was for our parents; to let them know their kids were in a safe building. A dozen years ago the school district decided to replace the old schoolhouse complex. Demolition took longer than expected. The contractor said it was the toughest demo job his firm had ever done. He said the buildings were so well reinforced that it took extra effort to bring them down.