If we use the 1906 San Francisco earthquake as a guide to the general level of destruction for a major quake in a large CA city then we get the following ...

* About 0.7-1% casualties amongst urban population
* About 56-75% of all city residents homeless after the quake
* Most destruction caused by fires after the earthquake

Here is the Wikipedia summary of the fires after the 1906 event:

"As damaging as the earthquake and its aftershocks were, the fires that burned out of control afterward were even more destructive. It has been estimated that up to 90% of the total destruction was the result of the subsequent fires. Over 30 fires, caused by ruptured gas mains, destroyed approximately 25,000 buildings on 490 city blocks. Worst of all, many were started when firefighters, untrained in the use of dynamite, attempted to demolish buildings to create firebreaks, which resulted in the destruction of more than 50% of the buildings that would have otherwise survived.
... As water mains were also broken, the city fire department had few resources with which to fight the fires. Several fires in the downtown area merged to become one giant inferno. Brigadier General Frederick Funston, commander of the Presidio of San Francisco and a resident of San Francisco, tried to bring the fire under control by detonating blocks of buildings around the fire to create firebreaks with all sorts of means, ranging from black powder and dynamite to even artillery barrages. Often the explosions set the ruins on fire or helped spread it."

This potential problem with fires is probably even worse for Los Angeles today because the density of structures has increased considerably. The worst-case outcome could potentially be real firestorms erupting in some high-density neighborhoods - since without water it would be impossible to put out the fires quickly. I doubt that firefighters will use dynamite these days - but we have portentialy many more sources of fire due to various industrial processes.

And going back to the casualty and homeless rates, if we apply them to the L.A. city region:

Casualties = approx 21,000 - 31,000 people
Homeless = 1.7 - 2.3 million people

and this is only using the population figures for Los Angeles (not counting Orange County or other bedroom communities).

Which raises an important point ... how many of these homeless people have EDC kits prepared and ready to go? And if their homes are destroyed by earthquake or fire - doesn't this mean that any emergency supplies stored inside their houses would also be destroyed as well?

Pete2