The San Andreas Fault is the largest and most well known fault in California
The most famous earthquake in California was the San Francisco earthquake in 1906. Most of the structures in San Francisco at that time were unreinforced masonry brick buildings- that completely collapsed during the violent shaking of the 7.8 magnitude quake. At the time, seismology was an emerging research field, and this quake was one of the first quakes to be studied using scientific techniques and measuring instruments.
The long beach earthquake in 1933, though much less deadly than the San Fransico quake three decades earlier, narrowly avoided a complete disaster. It occurred at 5:54pm, after school. The quake caved in several school buildings, and if it would have happened earlier in the day… you can imagine what a tragedy that would have been.
As a result of this earthquake, California instated seimic buiding codes to ensure that no public school was unsafe in California. This slowly carried over into residential building during the following 10 years.
In the past one hundred years, there have been four major earthquakes in Los Angeles: Long Beach 1933, San Fernando 1971, Whittier Narrows 1987, and the Northridge Quake in 1994. Earthquake Natural Hazard comes with the territory.