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Environment & Science

The science of tsunamis and SoCal




SEAL BEACH, CA - MARCH 11:  A lifeguard patrols Seal Beach, which was closed by authorities as a precaution against a possible tsunami following a massive earthquake in Japan March 11, 2011 in Seal Beach, California.
SEAL BEACH, CA - MARCH 11: A lifeguard patrols Seal Beach, which was closed by authorities as a precaution against a possible tsunami following a massive earthquake in Japan March 11, 2011 in Seal Beach, California.
David McNew/Getty Images

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Southern Californians had a brief scare early Tuesday morning when a powerful 7.9 magnitude quake off the coast of Alaska triggered a tsunami watch for us here thousands of miles to the south.

That watch is canceled. But if such a disaster were to strike, it could cause a serious amount of damage.

"Most areas along Santa Monica Bay are equally vulnerable," says Costas Synolakis, director of the Tsunami Research Center at the University of Southern California. "We're vulnerable to tsunamis from pretty much everywhere around the Pacific."

A tsunami that originates from a quake thousands of miles away wouldn't create the kind of massive flooding people saw in Japan in 2011. However, a tsunami would create problems in one specific kind of place.

"Ports are very vulnerable to very strong currents," he says.

In 2010, the Port of L.A. had to stop operations because of swirling currents created by a tsunami originating off of Chile's coast. And in 2015, another earthquake-triggered tsunami from Chile headed towards Ventura.

"It was hardly noticeable – less than half a foot high," says Synolakis.

But it generated strong vortices inside the harbor for about 36 hours.

Also, natural barriers like the Channel Islands offer little protection.

"It turns out that small islands, like Catalina or the Channel Islands, tend to focus the wave energy behind them," he says.

Imagine an island breaking the wave. When the wave is split, however, the two sides can re-merge in the middle and create a big wave that continues to head towards the coast.