San Francisco's emergency siren usually only sounds on Tuesdays as a test, but Thursday's alarm was a symbolic, if not jarring, reminder to be prepared for the next big one.
The purpose of "The Big Rumble" was to let people practice how to protect themselves during earthquakes and to get prepared at work, school and home.
"It was almost like an earthquake. It was a good learning experience I guess. I don't know what to really do during an earthquake. I talked to mom the other day and told her there was an earthquake warning and she said 'What do you do? Do you run outside?" Art University student Lisa Allen said.
The first ever, statewide earthquake drill happened just two days before the 20th anniversary of the /*Loma Prieta*/ quake. At 10:15 a.m. on the dot students took cover under their desks and emergency personnel rehearsed.
"I'm not sure that anyone is ever ready for a huge earthquake but we are certainly prepared and doing everything we can to make sure the citizens here in Hayward are safe and are all accounted for," Hayward Fire Department Captain Thor Poulsen said.
Hayward firefighters surveyed neighborhoods for damage. All went well in the mock disaster.
But that was a best case scenario; geologists say the Hayward Fault is a ticking time bomb.
For those that live and work in Hayward, the risks come with the territory. Uneven sidewalks are proof of the constant motion of a city built directly on the fault line. The Hayward Fault has shifted so much it caused structural damage to the old City Hall and forced the building to be closed. Now it is a question of whether residents in Hayward are ready for the next big quake.
"Anytime, any year, it can be one week or it can be next hour but I try not to think about it," Hayward business owner Rosario Cisneros said.