The temblor was followed by several aftershocks that were reported to be up to 3.5 magnitude, according to the Pacific Northwest Seismic Network.
The main quake was originally reported as 4.7 magnitude but was later revised down, according to the U.S. Geological Survey. The quake was approximately 2 miles from Monroe and 12 miles from Everett.
A number of people in the area said they felt the quake.
— Brit Moorer (@britmoorer) July 12, 2019
“Wow! Was just woken up by a 4.7 magnitude earthquake! Bed started shaking. First one I’ve felt since moving to Seattle. This was centered 2km N of Three Lakes, E of Everett, according to @USGS. Did you feel it?” said Preston Phillips, an anchor with KOMO, via Twitter.
Brit Moorer with King 5 said that the whole King 5 building in Seattle shook.
“Wow! Did anybody else feel that earthquake in Seattle? It went on shaking for a good 40-50 seconds!” added Diane Lewis of King 5.
Another person on the platform noted that there are a number of volcanoes in the region, sparking fears that the a quake could trigger one of them.
How many active volcanoes do I live by in Washington? ????
— Ranee Soundara (@naynerz) July 12, 2019
According to the survey, the intensity of the quake was four on a scale of 10 in the area around Everett.
The intensity dipped to three in most parts of the Seattle area.
Several other parts of the region felt the quake, including Olympia and Vancouver, Canada.
— jose (@jose93380940) July 12, 2019
— Manjula Iyer (@manjulaiyer) July 12, 2019
— Shelby【= ㅎ ◡ ㅎ =】 (@mymomsagingr) July 12, 2019
Quakes in the Pacific Northwest
According to the survey, “Earthquakes in the Pacific Northwest (PacNW) states of Washington and Oregon result from slip on faults in a variety of geographic and geologic settings. Earthquakes in much of the region are a consequence of stresses associated with motion of the Juan de Fuca Oceanic Plate to the northeast with respect to the North America Continental Plate at a rate of several cm per year.”
“This relative motion is largely made possible because the Juan de Fuca plate descends into the Earth’s mantle below the North American continent along what is called the Cascadia Subduction Zone, which extends from northwestern California through western Oregon and western Washington to Vancouver Island, Canada,” the survey stated.
“Relative plate motion that is not accommodated by subduction of the Juan de Fuca plate is accommodated by deformation of the overriding North America plate. Earthquakes are associated with both the subduction process and the deformation of the overriding North America plate.”