The USGS is a scientific agency of the United States Government. Scientists within this agency study our landscape, natural resources and the natural disasters that threaten them. This particular link shows a live map of current and past earthquakes throughout the United States.
FEMA was established in 1979. The primary purpose of FEMA is to coordinate additional response and relief when a disaster has occurred in the United States.
The SCEC website contains a wealth of information in regards to earthquake safety and preparedness. It also contains an online publication on making one's home safe in "Earthquake Country".
The EERI is a non-profit organization, which was funded in 1948. The objective of the Institute is to advance the science and practice of earthquake engineering, protecting people and property from the effects of earthquakes.
The Earthquake Country Alliance provides preparedness literature for Los Angeles and Southern California. This particular site contains informational videos, a wealth of preparedness data and tips for both homeowners and business owners.