Frequently Asked Questions (FAQ)
The answer to your qustion is probably here, or in the two links below.

How do earthquakes get on these maps?
The sequence of events leading to these web pages after an earthquake is detected.

What happens when I click on an earthquake?
Instructions on navigation and what to do if an earthquake is hidden.

Data Sources
Seismic networks and participating institutions.

Data Centers
Information about past earthquakes can be obtained over the internet from these centers.

Credits and Disclaimer
The people who made these maps possible.

Glossary
Explanation of terms found in the California-Nevada recent earthquake pages.

Other Sites that Host these Maps
Mirror sites and links to similar maps for other regions.