Following evacuation, Tsunami Warning Center says ‘better safe than sorry’

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A Sitka police officer directs traffic departing Sitka High School, as the evacuation ends and residents return home. (Emily Kwong/KCAW photo)

A 7.9 earthquake shook Alaska early this morning and spurred tsunami evacuation warnings for many coastal communities. But in the end, the waves peaked at less than a foot.

That’s according to the National Tsunami Warning Center in Palmer.

Peggy Johnson is a watchstander at the Warning Center. She says the tsunami was so small because of the type of earthquake that occurred. Called a strike-slip earthquake, the faults moved horizontally, not vertically.

“Because there was no vertical motion or very minimal vertical motion there was no significant tsunami generated,” Johnson said.

Johnson said within four minutes of the earthquake, the Warning Center received seismic data about its location and size. That then generated a computer model showing what areas were at risk.

“When it’s this large we have to send out a message that, in this case, for the size of the event and the location, it involved a warning and advisory for basically all the coastline of Alaska,” Johnson said.

Johnson said she is concerned Alaskans might not take the next tsunami warning seriously. But even though the earthquake didn’t lead to a large tsunami, the Warning Center prefers to take a cautious approach.

“We’d rather evacuate more people when we didn’t really have to, but they’re safe, rather than to do the opposite of being conservative and not evacuate when we should have,” Johnson said.

In the future, Johnson said Alaskans in coastal areas shouldn’t wait for official warnings if an earthquake lasts for 30 seconds or more, or if it’s so strong it’s difficult to stand.

“If you felt it and it lasts 30 seconds or more, evacuate,” Johnson said. “Go inland and up as quickly as you can.”

The National Tsunami Hazard Mitigation program advises people to prepare for a tsunami by having an emergency plan in place, to be aware of evacuation routes and to have a disaster supply kit at the ready.

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