Federal experts are already reporting aftershocks from Monday's deadly earthquake in central California.
The 6.5 magnitude quake killed two people, injured dozens of others and knocked down buildings.
The U.S. Geological Survey says the quake was followed Monday and early Tuesday by more than 80 aftershocks larger than magnitude three.
The biggest of the aftershocks was estimated at 4.7.
Emergency officials say there's a good chance that even stronger aftershocks will follow in the days ahead.