The 24-Hour Aftershock Forecast provided by the USGS indicates the probability of strong earthquake shaking (Modified Mercalli Intensity VI or greater—roughly, shaking strong enough to cause objects to fall off shelves) in the next 24 hours. Not all aftershocks are smaller than the quake that precedes them. If there was a minimal quake in recent hours, there may be a bigger shock coming, so check out this map to know what to expect.
This USGS map
of the California-Nevada region displays quakes with a magnitude of 1 or more that have been recorded in the last seven days. Click on one of the squares to learn more about a given event, or click “List of earthquakes on this map” for a full rundown, with magnitude, time, location, and depth. Or try the SCEC’s version
See where the faults lie in Los Angeles. The Southern California Earthquake Center has a similar clickable map detailing the (known) faults of Southern California. Click on a fault for more details.
Scenario shake maps describe the expected ground motions and effects of specific hypothetical large earthquakes. To find out how a big earthquake might hit your neighborhood take a look at scenario maps created for Southern California regions.
For the basics in earthquake cartography—learn how hazard maps are made and what they mean.