- guardian.co.uk, Thursday November 13 2008 17.41 GMT
When the Big One came, it was with more of a whimper than a bang. A distant, low rumble was followed by a man's voice calmly telling his 5m listeners to "drop, cover and hold on".
The rumbling turned to tinkling as windows shattered and glass fell to the ground.
"Drop to the ground immediately," he urged. "Take cover by getting under a sturdy desk or table; hold on to it until the shaking stops."
Across southern California, school children giggled and adults discovered the allure of sharing floor space with relative strangers.
The Great Southern California ShakeOut had been billed as the nation's largest ever earthquake drill, priming residents of the area considered to be most vulnerable to the Big One.
"It's what we call a teachable moment," said California State University Northridge geology professor Douglas Yule, who led his students from their classes to gather on the central plaza in the campus.
"The point of this exercise is to get people to take it seriously," he told his audience of about 100. "Don't just shrug it off. Put some water in your garage. Have a pair of shoes under your bed. What's going to happen is that it goes Third World for a while, no water, no power. Who remembers '94?"
The Northridge earthquake in 1994 was the last big quake to shake southern California, leaving 57 dead, buckling freeways and causing an estimated $20bn in damage.
One of the centres of the quake was the very spot where Yule was addressing his students. Across the plaza stands a monument to those who worked to reopen the campus.
Dave Liggett, now a geology technician at the university, remembers the 1994 quake as a bonding experience.
"The house shook pretty good," he said. "The biggest mess was the pancake syrup. People in my neighbourhood are pretty independent. For many the first time you met your neighbour was on that morning."
The Northridge quake was a 6.7 magnitude tremor; Thursday's drill was based on something far more fearsome, a 7.8, 200-mile long shock spreading along the southern San Andreas fault from the desert near San Diego to Los Angeles. A model developed by the US Geological Service envisages 1,800 deaths, 50,000 injuries and $200bn in damage. Fifteen million people in southern California could be left for weeks without power, and months without water.
An earthquake of a similar magnitude to the drill takes place every 150 years on the southern San Andreas fault. The last one was 151 years ago and scientists warn that the fault is "10 months pregnant".
"We're talking about an earthquake 50 times stronger than '94," Yule told his now attentive audience. "In '94 this campus was devastated by an earthquake that lasted 10-15 seconds." The model for the next Big One assumes tremors lasting three minutes.
Organisers for the ShakeOut received a boost in the summer when the Chino Hills earthquake delivered a 5.4 magnitude shock to an area 30 miles east of Los Angeles. While that roused public and official interest in the event, leading to 5m registrations, the biggest motivator behind the ShakeOut was Hurricane Katrina in 2005.
"New Orleans knew what could happen," said Yule, "but they didn't prepare adequately. Everyone here needs to take personal responsibility. Don't expect to be bailed out."
With preparation, he declared, there could be an upside to the whole shebang. "We're all going to suffer," he said. "But with some preparation I can be looked on as a great adventure, something you can tell your kids about."