Seismic Retrofitting is the modification of existing buildings to make them more resistant to seismic activity and earthquakes
The Long Beach earthquake of 1933 alerted Californians of the need to engineer earthquake safe buildings and reinforce existing buildings with seismic retrofitting.
Homes built before 1933 in Los Angeles were built without being bolted to their foundations. Houses built between 1933 and 1940 may or may not have bolting as this is when bolting was starting to become common building practice.
One of the reasons the San Fransico Earthquake of 1906 was so devastating was because it left an estimated 300,000 bay area residents homeless after the quake. With no place to live, and no access to food and water, these earthquake victims had to rely on temporary housing shelters and emergency aid.