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Alaska hit with 8.0 magnitude earthquake; no tsunami threat for coastal B.C.

An 8.0 earthquake off the Aleutian Islands triggered a tsunami warning for parts of Alaska this afternoon

The U.S.’s National Weather Service initially issued a warning for coastal areas of Alaska from Nikolski to Attu— but it’s has since been downgraded to a tsunami advisory.

The B.C. coast is outside of the tsunami advisory area.

The Pacific Tsunami Warning Center says the earthquake is too deep, 114 kilometres down, to pose a tsunami threat along the Pacific Coast areas of Canada and U.S.

Dr. Brent Ward, earth scientist at Simon Fraser University, says it sounds like the earthquake occurred in the subduction plate — as opposed to along the subduction zone — which means there wouldn’t have been much seafloor movement.

“You need the seafloor movement to generate a tsunami,” Ward said. “When you move the seafloor — punching up from the bottom — it displaces the water and that’s what generates the wave.”

Still, an 8.0 quake is a very significant event, said Ward.

“Anything over 8.0 we call a great earthquake and we only get about 15 or so of those a year of that magnitude around the world” — Brent Ward, SFU

There have been no immediate reports of damage, but Natasha Ruppert, a seismologist with the Alaska Earthquake Center, told the Associated Press that the communities that would have suffered damage are also under tsunami warnings, so people may not have been able to get out and check for damage yet.

From the AP story: “The National Tsunami Warning Center in Palmer, Alaska, issued a tsunami warning for coastal areas between Nikolski to Attu, on the Aleutian Islands. A warning means significant inundation is possible or occurring. Residents are being warned to move inland toward higher ground.
A tsunami advisory was also issued for coastal areas stretching from Nikolski to Unimak Pass. An advisory means strong currents or dangerous waves are expected, but widespread inundation isn’t likely.”

CNN is reporting that the town of Adak evacuated its 150 residents to a shelter about 600 feet above sea level.

Google has a live epicenter map of the quake that was centred 24 kilometres southeast of Little Sitkin Island, Alaska.

Source: http://blogs.vancouversun.com/2014/06/23/alaska-hit-with-8-0-magnitude-earthquake/