With movies like San Andreas portending doomsday scenarios that are light on science and heavy on CGI effects, we decided to consult a seismic science expert. Professor of Physics Gregory Lyzenga ’75 offers some useful—and factual— information about earthquakes.
Earthquake forecasting—estimating regional probabilities over time—is undergoing continuous refinement, but predicting their precise timing, location and size will probably never be possible, he says. Development is underway of a warning system that can alert population centers of a large earthquake seconds to minutes before the seismic waves will reach the region.
Shake, Rattle or Roll
How we experience quakes is a question of proximity and observers’ conditions, rather than intrinsic scientific properties, says Lyzenga. Often the same earthquake is reported by nearby observers as a sharp jolt and by distant ones as rolling—a natural consequence of the way that seismic waves disperse and attenuate with distance.
What About That Tsunami?
“We do not have subduction faults in Southern California that are capable of producing magnitude 9 events,” he says, and so do not have the potential for an earthquake/tsunami scenario, as we saw in Japan in 2011. Secondary faults offshore, like those in mountain and desert regions, are potential contributors to the “overall seismic hazard,” however.
If an earthquake is strong enough for you to feel in a car, it may be intense enough to damage infrastructure, bridges or roadways. Act according to conditions and stop driving if it appears dangerous to continue.
Be Calm, Be Aware
Whether in or outdoors, the most probable cause of injury during an earthquake is falling objects or debris, says Lyzenga. Stay put and find cover under sturdy furniture. After a quake, look out for fallen power lines, busted gas lines, fire hazards and broken glass. “Most of it is common sense. Irrational fear during an earthquake is not helpful, and modern structures are very unlikely to collapse, so running outside is also probably not a good idea,” he says.