Very minor earthquakes occur frequently in Southern California; most of the time they're so slight that you won't notice them. If you feel a stronger tremor, follow basic safety precautions. If you're indoors, take cover in a doorway or under a table or desk—whichever is closest. Protect your head with your arms. Stay clear of windows, mirrors, or anything that might fall from the walls. Do not use elevators. If you're in an open space, move away from buildings, trees, and power lines. If you're outdoors near buildings, duck into a doorway. If you're driving, pull over to the side of the road, avoiding overpasses, bridges, and power lines, and stay inside the car. Expect aftershocks, and take cover again if they are strong.
Of the Metro lines, the Red, Green, and Expo lines are the safest and are more regularly patrolled. The Blue Line can be sketchy after dark. Avoid riding in empty cars, and move with the crowd when going from the station to the street.