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When it comes to earthquakes, only Alaska surpasses Oklahoma

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Earthquakes in Oklahoma
Violet Hassler | Enid News & Eagle

ENID, Okla. — With its volcanoes, glaciers and mountains, Alaska’s landscape may be different from Oklahoma’s. However, the two states have frequent earthquakes in common.

Out of all the states in the nation, Alaska is the only state surpassing Oklahoma when it comes to earthquakes, U.S. Geological Survey records indicate.

As of Aug. 31, more than 600 magnitude 3.0 or greater earthquakes had been recorded in Oklahoma so far this year, according to Oklahoma Geological Survey. By the same date, more than 900 magnitude 3.0 or greater quakes had been recorded in Alaska, USGS records show.

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Both numbers are significantly higher than California’s earthquake count — just more than 90 magnitude 3.0 or greater earthquakes this year, according to USGS.

As is the case with California, though, the earthquakes in Alaska are different from those occurring in Oklahoma, USGS officials note.

Included in the total number of Alaska quakes so far this year, are nearly 200 temblors measuring 4.0 or greater, as well as just more than 30 measuring between magnitude 5.0 and magnitude 6.0. There have been three quakes measuring magnitude 6.0 or greater. USGS records show Oklahoma has had just 16 magnitude 4.0 or greater quakes and none measuring magnitude 5.0 or stronger this year.

USGS Geophysicist George Choy said the Aleutian trench, running along Alaska’s southern coastline, has numerous earthquakes, as it is the plate boundary between the Pacific and North America plates.

“Alaska is seismically active even inland. Its oceanic boundary is at the junction of the Aleutian arc and the transcontinental strike-slip fault that ... begins with the San Andreas Fault in California and continues through Canada and into southern Alaska as the Queen Charlotte, Fairweather and Denali faults,” he said. “The subduction is complex as the Aleutian Trench is trying to consume the strike-slip fault. In addition, the Yakutat Terrane, a broken crustal block which is colliding with the North American continent, is resisting subduction because of its buoyant crust.

“The earthquakes arise from the intracontinental plate deformation and the large zone of crustal compression inland far behind the coast of Alaska.”

When it comes to the number of earthquakes within the continental boundary of California, Choy said there were about 200 magnitude 3.0 or greater quakes in 2014. In Oklahoma, there were 585.

“However, the sheer number of earthquakes is not the whole story. Total energy release is very different,” he said. “In 2014, California had earthquakes of M5.1 (Southern Calif.), M6.0 (Napa) and M6.8 (offshore Cape Mendocino) that were much larger than any earthquake in Oklahoma.”

Over time, seismicity in California, as with all active earthquake sources in the world, will average out, he said.

“Sometimes, there is a large earthquake which is followed by a long series of aftershocks. The aftershocks will inflate numbers for a short time,” he said. “Fluctuations are normal.”

When it comes to other states this year, USGS records indicate 24 states have had earthquakes registering magnitude 3.0 or greater. Among those states are Hawaii with approximately 45 significant quakes, Kansas with nearly 80 earthquakes and just more than 80 earthquakes within or near Oregon’s borders.

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