7.7-magnitude BC quake generates tsunami

A magnitude 7.7 earthquake struck Queen Charlotte Island at 8:04 p.m. Saturday, according to the U.S. Geological Survey. Ocean sensors have detected a small tsunami from the earthquake.

The coast of Washington and Oregon is not threatened, but tsunami warnings were put in place for parts of the British Columbia and Alaska coastline, as well as in Hawaii, with waves expected to reach the islands mid-morning Sunday.

A tsunami warning means that all coastal residents in the warning area who are near the beach or in low-lying regions should move immediately inland to higher ground and away from all harbors and inlets, including those sheltered directly from the sea.

A tsunami advisory has also been issued for the Southern Oregon coast and Northern California coast. A tsunami advisory means that a tsunami is expected but not likely to cause significant widespread inundation. Currents will be risky for swimmers and boats.

An “information only” notification for the Northern Oregon and Washington coasts remained in place as of 11 p.m. Saturday.

Revisions to tsunami warnings and advisories are occurring regularly. Updates can be found online at http://www.tsunami.gov/

The quake struck in the Gwaii Haanas National Park Reserve on the southern tip of the island, about 86 miles south of Masset, British Columbia.

The number of people possibly affected by the quake itself is about 20,000, the USGS said.

The quake, which was followed ten minutes later by a 5.8 magnitude aftershock and several others of smaller magnitude, prompted a tsunami warning for coastal areas of British Columbia and Alaska between the northern tip of Vancouver Island and Cape Decision, Alaska, about 85 miles south of Sitka.

A tsunami warning was also issued for Hawaii late Saturday night. The estimated arrival time for the first tsunami waves in Hawaii is 10:28 p.m. Hawaii time.

The West Coast/Alaska Tsunami Warning Center also issued a tsunami information bulletin issued for the coast of Washington, Oregon and other parts of the Pacific Rim outside of tsunami warning area. No destructive widespread threat was seen there based on historical earthquake and tsunami data.

After 10 p.m., a tsunami advisory was issued for the rest of coastal British Columbia, south to the Washington border. The more severe tsunami warning zone was not extended south, however.

A number of aftershocks, ranging in magnitude of 4.6 to 5.8, have followed the initial quake.