Magnitude 7.8 Earthquake Rocks Alaska

Alaska earthquake

A tsunami warning has been canceled after a 7.8 magnitude earthquake struck off the coast of the southeast of Perryville, Alaska.

The National Weather Service Pacific Warning Tsunami Center confirmed the tsunami warning was canceled after a warning was triggered in parts of the state following an earthquake on July 22.

Here’s what you need to know:


The National Weather Service Issued an Earlier Tsunami Warning

The National Weather Service issued an alert including tsunami advisories for southern Alaska and the Aleutian Islands, “in addition to the original warning area” of South Alaska and the Alaska Peninsula. The scale of the earthquake was upgraded from 7.4 to 7.8.

The alert from the Weather Service confirmed “a tsunami was generated by this event, but no longer poses a threat.” The service also said “for other U.S. and Canadian Pacific Coasts in North America, there is no tsunami threat.”

The NWS said the quake did not pose a tsunami threat to Hawaii, California, Oregon or Washington state.

News meteorologist Andy Moffitt said the “West Coast appears to be in the clear.”


The Earthquake was the Result of a ‘Rupture Occurring on a Fault’, the United States Geological Survey Said

The United States Geological Survey said the earthquake “occurred as the result of thrust faulting on or near the subduction zone interface between the Pacific and North America plates.

“The preliminary focal mechanism solution indicates rupture occurred on a fault dipping either shallowly to the northwest, or steeply to the southeast.

“The location, mechanism and depth – and the large size of the event – are all consistent with slip occurring on the subduction zone interface between the two plates.”

The United States Geological Survey went on to say large earthquakes were common in the “Alaska-Aleutian subduction zone,” with six other earthquakes occurring since 1900 occurring within 250 km of the July 22 event.

There was an 8.2 earthquake in 1938 in an “almost identical location,” and the Alaska-Aleutian Trench “also hosted the second-largest earthquake recorded by modern seismic instrumentation” in 1964, a 9.2 magnitude earthquake, producing a small tsunami “that was recorded both locally and in Hilo, Hawaii.”

The July 22 quake “was centered 60 miles, or 98 kilometers, south-southeast, of Perryville, Alaska,” according to a U.S. Geological Survey data and CNN. “The quake is considered shallow at about six miles, or 10 kilometers, deep.”

CNN meteorologist Allison Chinchar said “Anything below 70 kilometers is considered a shallow quake … that’s important, because shallow earthquakes often cause the most damage, compared to the ones that are deeper, regardless of the strength.”

Doors were opened to evacuees at local schools on Kodiak Island.

According to ABC and the Daily News, Larry LeDoux, superintendent of the Kodiak School District, said, “We’ve got a high school full of people … I’ve been passing out masks since the first siren sounded… Everything’s as calm as can be. We’ve got probably 300, 400 people all wearing masks.”

Evacuation sirens were heard in videos filmed in Kodiak and posted to Twitter. KTVA TV’s Joe Vigil said on Twitter, “A friend in Kodiak just told me another quake just hit. They felt it. Tsunami warning sirens are going off again. This is video from Kodiak just a few minutes ago.”

A journalist posted a video describing “sirens blasting” and “sounds of helicopters in the air.”

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