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7.5 quake in Southeast triggers tsunami warning for Alaska coast

NOAA photo

A magnitude 7.5 earthquake rocked the waters off of Southeast Alaska just before midnight Friday, triggering a tsunami warning that stretched from the coast of British Columbia all the way up the Southeastern Pandhandle to Cape Fairweather, about 80 miles southeast of Yakutat. All warnings were cancelled by the Alaska Tsunami Warning Center at about 2 a.m. Saturday.

Tsunami advisories were briefly in place from the Washington state and Canadian border to the Kennedy Entrance, 40 miles southwest of Homer, but those advisories were cancelled shortly before 1:30 a.m. Saturday. Also cancelled was the portion of the warning in effect north of Cape Fairweather stretching to Cape Suckling, 75 miles southeast of Cordova.

According to the Alaska Earthquake Information Center, which was under heavy traffic Saturday morning, the quake was initially measured at a magnitude of 7.2, at a depth of 14 miles and 67 miles west of the community of Craig. The U.S. Geological Survey put the quake 63 miles west of Craig and initially estimated it at magnitude 7.7, later downgraded to 7.5. The depth was also estimated at a shallower 6.2 miles.

Another magnitude 4.7 quake also occurred in the same area just before 12:30 a.m. Saturday, with a 4.2 aftershock following shortly after.

The following warning was issued to those in areas that could be affected by high waves resulting from the earthquake:

Recommended Actions: If you are in a warning area - move inland to higher ground. If you are in an advisory area - move off the beach and out of harbors and marinas. Widespread inundation of land is not expected for advisory areas. Be alert to instructions from your local emergency officials. Do not go to the coast to observe the tsunami. Do not return to the coast until local emergency officials indicate it is safe to do so. ... The tsunami message will remain in effect until further notice. Refer to the Internet site wcatwc.arh.noaa.gov for more information.

An employee contacted at the Sitka Police Department at 1:14 a.m. -- about a half-hour after the tsunami was estimated to arrive in that community -- said that they hadn't yet gotten any news of increased wave activity, but people were evacuating to higher ground and the tsunami warning sirens had gone off in the community.

The city of Craig, Alaska tweeted just before 1 a.m. that evacuation was voluntary, and the community's school and gym had been opened to the public. At 1:44 a.m., the city tweeted that "evacuation points are standing down. Please continue to be aware of aftershocks that may occur."

A small tsunami was observed in the community of Port Alexander shortly after 1 a.m., the Alaska Tsunami Warning Center reported. That wave height was only a half-foot above the norm. Sitka experienced an even smaller wave.

The center warned that some areas may continue to see small sea level changes for several hours.

"A tsunami was generated during this event but no longer poses a threat," the center reported.

Also briefly on the list for a potential bump in wave height was the area surrounding Kodiak Island, where the Shell drill rig Kulluk has been grounded in shallow water off the coast of the nearby Sitkalidak Island since New Year's Eve.

For more information, visit the Alaska Tsunami Warning Center, or if that's under heavy traffic and not responding, Google is providing the advisory as well.

Contact Ben Anderson at ben(at)alaskadispatch.com