Residents on the Northern California coast were urged to quickly evacuate Thursday morning and were told to seek higher ground after Magnitude 7 earthquake off Humboldt County triggered a tsunami warning.
The alert just before 11 a.m. warned that “a tsunami with devastating waves and a powerful current is possible.”
But about an hour later, the alert was canceled.
To some, it felt like an emergency shot. Others remained confused.
But officials say they followed the correct protocol for responding to a potentially dangerous tsunami and that it was necessary to give residents enough time to get to safety.
“The weather has to be respected to keep people safe,” said Dave Snider, tsunami warning coordinator at the National Tsunami Warning Center in Alaska.
“The No. 1 challenge with tsunamis is that we know a major event has occurred,” Snider said of the earthquake. “We don’t know if a tsunami is actually happening.”
Given the magnitude and location of the earthquake, his team immediately implemented its procedures for a potential tsunami, and the first step is to issue as targeted an alert as possible.
“There are only two ways for us to know a tsunami is happening: we have buoys on the high seas and we have coastal observation stations in ports and harbors – that’s it,” Snider said. “We want to beat this wave and we want people to move away too…before we see this wave.”
So initially, Snider said, there was no confirmation that a tsunami was heading toward the West Coast, but all the ingredients for such a tsunami were present. The earthquake’s proximity to the California coast made it particularly urgent to begin evacuations, because if a tsunami formed, it could strike much more quickly than a seismic event further out to sea, he said.
“We are completely reactionary to the earthquake,” Snider said.
After issuing a warning, his team spends the next 30 minutes to an hour understanding the earthquake’s “failing mechanism” to determine how it shook the earth, confirm its magnitude and monitor buoys and coastal lookouts for further signs of a growing tsunami. All these factors confirmed positive news: no major tsunami, no signs of danger. The warning has been canceled.
He knows the back and forth can be frustrating, but he wants people to understand that it’s better to be overprepared than the opposite.
“The feeling is: ‘Nothing happened, why did I evacuate?’ » Snider said. “No, you did the right thing. …That could have moved a lot of water. We’re glad that’s not the case.
Shortly after the tsunami warning was canceled, Snider said, his team determined that a small tsunami — measured at 5 centimeters — had occurred at Arena Cove, off the coast of Mendocino County.
“Something has happened, something significant has happened on our planet,” Snider said.
During the hour that the tsunami warning remained in effect, authorities in Del Norte, Humboldt, Mendocino, Berkeley and San Francisco counties urged coastal residents to evacuate inland.
At Fort Bragg, boat owners were quickly trying to get their boats out of the harbor.
Sirens sounded in Ferndale, signaling necessary evacuations.
In San Francisco, firefighters roamed the beaches yelling at people to “clear the beach, tsunami warning.”
Dan Beniflah was walking his dog on the beach before firefighters arrived. He said the warning sounded like a tsunami alert that happened decades ago, but he recalled that “nothing ever happened.”
Like then, the water Thursday seemed normal, he said.
Snider, however, urged people not to ignore these warnings – which remain quite rare – and not to go to the beach to watch the waves.
“Refresh what it means to live in a tsunami-affected country,” Snider said.
Staff writers Ruben Vives, Jessica Garrison and Hannah Wiley contributed to this report.
