Some 5 million people are today taking part in the Great Southern California Shake-Out, a drill based on a pretend earthquake measuring 7.8 on the Richter scale.
In view of the number of fault lines and earthquakes in the region, it is undoubtedly a very good idea to prepare for the worst, and could potentially save many lives.
However, I do feel that the motto "Drop, Cover and Hold"

and the underlying message are reminiscent of the 1950s "Duck and Cover" campaign:
The latter may have been about how to react to a nuclear attack, but both suggest that cowering or hiding under a table is enough to survive the effects of such disasters - which perforce also include collapsing buildings. So unless tables are much stronger in the US than in Europe, I would guess that the practice is as useless a survival tactic as cowering in the event of a nuclear explosion.
