FEMA’s EMI site. The independent study program is accessible here.
In particular, these two courses would be a good place to start:
There is also an Introduction to ICS for federal employees, and numerous other courses available, with course materials.
A collection of amateur radio groups in the Southern California area.
The State of California has made a number of strides towards preemptively engaging the citizenry prior to major disasters. The DisasterVolunteers section of the California Volunteers site is a good jumping off point for Californians looking to become more involved.
In particular, you should look at the California Citizen Corps, the Community Emergency Response Teams program, and the Medical Reserve Corps (more information on all those here).
The State of California’s Office of Emergency Services has an information system that allows people to subscribe to alerts, or browse them via the web.
There is also this web service, Nixle, which is used by the LA County Sheriff’s Dept. and others to send out alerts.
The 911.gov project over at the University of Maryland’s Human-Computer Interaction Lab looks intriguing. Ben Shneiderman gave the keynote at last year’s ISCRAM, and also had a conference paper on the community response grid project.