January 5, 2013

Powerful 7.7 Magnitude Quake Hits West Of Alaska Coast - Tsunami Warning Issued For Alaska And British Columbia Coasts

A major earthquake shook an area off the coast of Alaska, but was not strong enough to generate a tsunami threat to Hawaii.
The Alaska Tsunami Warning Center issued this map of areas under either a tsunami warning (in red) or advisory (in orange).

The quake was measured at a magnitude 7.7, according to the U.S. Geological Survey. The earthquake reading was based on the open-ended Moment Magnitude scale used by US seismologists, which measures the area of the fault that ruptured and the total energy released.

The earthquake happened at 10:58 p.m. HST, about 63 miles southwest of Craig, Alaska.

The Pacific Tsunami Warning Center said there was no widespread threat of a tsunami at this time, but it issued a regional warning affecting the Alaskan coast in the proximity of the epicenter.

The west coast and Alaska tsunami-warning center has issued a regional tsunami warning and/or watch and/or advisory for other parts of the pacific located closer to the earthquake. Based on all available data there is no destructive tsunami threat to Hawaii.

However, some coastal areas in Hawaii could experience small non-destructive sea level changes and strong or unusual currents lasting up to several hours. The estimated time such effects might begin is 4:28 am Hawaii time.

Tsunamis can be dangerous waves that are not survivable. Waves heights are amplified by irregular shorelines and are difficult to forecast. Tsunamis often appear as a strong surge and may be preceded by a receding water level. Marines in water deeper that 600 feet should not be affected by a tsunami. 

Waves heights will increase rapidly as water shallows. Tsunamis are a series of oceans waves, which can be dangerous for several hours after the initial waves arrival. Do not return to evacuated areas until an  all clear is given by local civil authorities. Pacific coastal regions outside California/ Oregon / Washington / British Columbia and Alaska should refer to the pacific tsunami warning center messages for information on this event at: http://ptwc.weather.gov



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