5.1 quake rattles San Francisco Bay

A 5.1-magnitude earthquake struck the San Francisco Bay area just before noon local time on Tuesday.

It was the region’s largest quake in eight years, since a 6.0-magnitude shaker in 2014.

Multiple agencies reported that there was no reported damage or emergency calls regarding injuries.

The quake hit the Calaveras Fault, which last produced a 6.2-magnitude earthquake in 1984. The Calaveras is one of six geologic faults around the bay, and a local branch of the 800-mile long San Andreas Fault.

The epicenter of the quake was in the hills east of San Jose. Five minutes later, a 3.1-magnitude aftershock struck a half-mile east of the original tremor.

Public transit agencies announced changes of plans due to the quake. For example, ferry departures on the bay were delayed for 10 minutes as terminals were inspected. BART trains were initially put on hold for five minutes, then renewed operating at a reduced speed.

For comparison, the 1989 "World Series" quake was a 6.9 on the Richter scale. Dozens of people were killed, and damage was in the billions of dollars. The Richter scale of intensity or energy release says that a 6 is ten times more intense than a 5, and a 7 is 100 times more intense than a 5.