Ever wonder what the numbers mean when it comes to earthquake magnitudes? Here's a look. Get the latest on the 5.1 quake that hit 12 miles east of SanJose:
Seismologist Dr. Lucy Jones joined ABC7 News to break down Tuesday's earthquake and the Calaveras fault.
"The Calaveras moves more slowly, it has less of the total motion going on there than on the San Andreas, so it moves less often or releases less energy. But it seems to have the smaller earthquakes a lot more often," said Dr. Jones. "It's considered capable of a six and a half or so 6.7. But unlike the San Andreas it's not going to have, you know, a magnitude eight."
Nearly 100,000 people reported receiving a warning before the shaking started through California's earthquake early warning system, according to the California Governor's Office of Emergency Services, or Cal OES.