It left most residents feeling shaken but not stirred. A 4.0 earthquake rattled through parts of the Bay Area Monday morning at 6:49am. The tremors were widely felt through Oakland and Piedmont with lesser shaking experienced in San Francisco. The short quake was described as sounding like the breaking of a tree branch and was followed by seven short aftershocks. There were no reports of damages or injuries but even these so-called “light” quakes inevitably bring up concerns about the “big one,” that estimates say could leave 20,000 dead and cause more than $32 billion in damages.