A series of temblors that has rattled Northern California since Sunday should serve as a reminder that a major earthquake is on the state's horizon. The USGS recorded more than 60 small earthquakes in the San Ramon Valley 26 miles east of San Francisco -- between Sunday and Tuesday morning. The largest, a 3.9 magnitude shaker, kicked off the swarm at 7 a.m. on Sunday, and the region hasn't stopped moving since. The fault which produced the seismic swarm was unknown before Sunday and intersects the active part of the much larger Calaveras fault. "It really shows the high level of stress in our region that the small faults are beginning to fail," Schwartz said. "The concern we have is anything this earthquake sequence does that affects the occurrence of a larger quake on the Calaveras." Scientists say hundreds of deep, unmapped faults are scattered through the Bay Area, which are only discovered when they produce quakes, such as the 5.2 Yountville earthquake, which injured 25 people in 2000. "You could consider this a wakeup call for people," said Bob Urhammer, a research seismologist at the U.C. Berkeley Seismological Laboratory. "Everyone should keep in mind that there's a 70 percent chance for a 6.7 or higher earthquake in the Bay Area within the next 30 years." One of the main reasons I never moved to the West is if God forbid I lose a loved one or die with them, I'd never be able to forgive myself for moving there.