Although the first waves of the tsunami along many northern California coastal areas appeared to be harmless Friday morning, it is not reason enough to believe the danger is over, geophysics experts say.
Paul Segall, a professor of geophysics at Stanford University, advises residents of the California coastline to stay away from low lying areas – elevations 100 feet above sea level – for up to 10 hours after a tsunami alert is issued.
Segall noted the 1964 tsunami of Good Friday that hit Crescent City, Calif., in the aftermath of a magnitude 8.8 earthquake in Alaska.
After the first wave came into Crescent City that day, locals ventured down to the beach without the knowledge that a tsunami’s sequence of waves can take many hours to come ashore. As a result, approximately 11 people died when waves overtook them and swept them into the ocean.
Today, in the aftermath of Japan’s 8.9 earthquake, Crescent City has been hit again. According to the Associated Press, five people were swept out to sea off the coast of Crescent City this morning. Four have been rescued one man is still missing.
“Tsunamis take different forms depending on the profile of the shore and ocean bottom,” said Stanford University’s geophysics department chair, Greg Beroza. “I wouldn’t recommend going down to the shore to see it come in.”
When individuals hear the word tsunami, they expect to see Maverick-like waves, but breaks between tsunami waves can, in fact, span 15 minutes. Regular surf waves, which break nearly every 10 seconds, are triggered by wind stress, Segall said.