More than 8.5 million Californians will be refilling emergency kits, ducking under tables or standing in doorways as they participate in the largest earthquake drill the world has ever seen Thursday morning, the Federal Emergency Management Agency said.

The Great California ShakeOut is organized by the Earthquake Country Alliance and "continues to grow as the largest earthquake drill in U.S. history," FEMA Regional Administrator Nancy Ward said.

More than 1.3 million Bay Area residents are expected to participate in the drill at 10:20 a.m., including private businesses, school districts and city offices.

BART will stop all trains for about one minute at 10:21 a.m.

Hayward City Hall will be hosting a community event in honor of the statewide drill. Earlier that morning, the city will hold sessions on how to retrofit homes and equip a preparedness kit, city officials said.

All San Francisco Unified School District sites will also be participating, with San Francisco Mayor Ed Lee participating at William Cobb Elementary School, the school district said.

Marin General Hospital will be hosting Northern California's only "Quake Cottage," a mobile earthquake simulator that demonstrates how an 8.0-seismic event would feel, hospital officials said.

People can register to participate at www.shakeout.org.