The ShakeOut -- the biggest earthquake drill in the nation, with more than 9.3 million registered to participate in California alone -- is meant to teach earthquake preparedness and safety.
In San Francisco's Bayview District Thursday morning, Mayor Ed Lee, Fire Chief Joanne Hayes-White and police Chief Greg Suhr took cover under a school desk in a third-grade classroom at Dr. Charles R. Drew Elementary School.
At 10:18 a.m., the drill began with a bell and a recorded voice that said over a loudspeaker, "This is an earthquake."
The students headed under their desks, with one hand covering their necks and the other grabbing onto a desk leg, as they have practiced. They then followed Lee, Hayes-White and Suhr to the schoolyard, where the entire student body met as part of the drill.
Lee told the students they had participated in the drill along with thousands of students at other schools, as well as many residents in the city and the greater Bay Area.
"We want you all to be safe," Lee said. "We have to take care of things that might hurt us."
He reminded students that practicing during these drills is essential to be ready for the next earthquake that is predicted to strike the region within the next 30 years.
Further south at the Tech Museum in San Jose, hundreds of students, museum patrons and staff practiced how to "drop, cover and hold on."
Even while visiting a museum an earthquake can strike -- a message Thursday's drill stressed.
In Marin County, firefighters from the Marin County Fire Department encouraged residents to practice staying put and covered until the shaking stops -- as people should do if an earthquake was occurring.
On Wednesday's anniversary of the 1989 earthquake that killed 63 people and injured nearly 4,000 and seriously damaged Bay Area homes, freeways, buildings and other structures, Mayor Lee announced the appointment of Patrick Otellini as director of San Francisco's Earthquake Safety Implementation Program.
The program has goals laid out for the next 30 years that will work toward ensuring residents can safely stay in their homes or buildings following a temblor.
Additionally, the earthquake safety program aims for residents to have access to services soon after a quake that will help lead to a swift return to normalcy.