The last major quake on the Hayward Fault was in the mid-1800s, before the region became packed with properties worth an estimated $1.5 trillion.

The fault has been pretty quiet since that 6.8 magnitude event but, today, a shaker that strong could buckle Interstate 80, I-880 and partially collapse the Caldecott Tunnel — even damaging the supposedly quake-resilient new eastern span of the Bay Bridge.

Look close and you can see signs of the slow creep of the Hayward Fault all around the East Bay.

via Cal Scientists Go Underground To Monitor Hayward Fault Heartbeat « CBS San Francisco.