SAN FRANCISCO (KRON) — Earthquake drills are happening all over California Thursday for the annual Great California ShakeOut.

Students across the state will be asked to drop, cover and hold during the earthquake drills.

BART will also particpate in the drills by triggering an early warning earthquake alarm at 10:20 a.m. If you’re riding BART at that time, expect the trains to slow down.

The ShakeOut, which began in 2008, is the largest earthquake drill in history with millions of people participating throughout California. In San Francisco, more than 335,000 people are expected to participate.

The drill is deisgned to make sure people are ready for a massive quake. It teaches what to do before, during, and after a tremblor as well as helps prepare homes, workplaces, and schools for any type of emergency.