In the past 24 hours, more than 50 earthquakes have been discovered off the coast of Oregon, prompting seismologists to assure residents of the Pacific Northwest that they are not in danger. Researchers say that the Blanco Transition Fault Zone is very active, but it poses a small threat.
The Blanco Transition Fault Zone off the coast of Oregon is known for its activity and has not disappointed in the past 24 hours. At least 50 earthquakes have occurred, two of which have a magnitude of 5.8.
This sounds a lot-but scientists say that whether it is a tsunami or a strong earthquake affecting the continental United States, this fault will hardly cause disaster.
According to the U.S. Geological Survey, this group of earthquakes occurred about 200 miles from the coast. When people notice this, they worry that seismic activity may herald a major earthquake.
"Is that the Cascadia subduction zone talking?" A Twitter user replied to a post from the U.S. Geological Survey about a magnitude 5.8 earthquake. "Because that would be bad," they said, referring to the fault line extending from Northern California to British Columbia.
"The Blanco fault zone is not directly connected to the subduction zone, so it will not affect the large faults below the land (the Cascadia giant thrust fault)," NASA Jet Propulsion Experiment in Pasadena, California Said Eric J. Fielding, a geophysicist in the laboratory.
"Blanco's M5 earthquake is very common and has never occurred on land. Real-time plate tectonics," said seismologist Lucy Jones, referring to magnitude 5 earthquakes in the area.
The Blanco fault zone is a transition or strike-slip boundary; this means that it is a place where tectonic plates slide against each other. The most dangerous and powerful faults usually appear in subduction zones, where one plate dives under another.
"This may be the most active fault for earthquakes near North America, and this is not something to be wary of," said Harold Tobin, a professor at the University of Washington and the director of the Pacific Northwest Seismic Network.
The Blanco zone is farther in the ocean than the Cascadia subduction zone. Fortunately, there have been no earthquakes in the Cascadia subduction zone since 1700.
Due to the frequent activities and proximity to the coast in the Blanco area, it has become a favorite study area for seismologists and researchers. As geologist Dana Hunter once said, “BFZ is great, it’s fun to understand!”
In explaining one reason why a fault earthquake is unlikely to be felt on the coast, Hunter pointed out that Blanco has a "young, warm crust" — even likened it to freshly baked cookies — and added that the Part of the crustal sea floor is more prone to collapse instead of transmitting powerful seismic waves to Oregon and California.
Scientists often say that people living on the Oregon coast should not worry about the tsunami from the Blanco Fault.
Seismologist Jochen Braunmiller said when studying the area at Oregon State University in 2008: “You need a considerable amount of vertical displacement on the seafloor to produce a tsunami, and an earthquake along the Blanco fault does not produce a tsunami.”
In the same year, Braunmiller and his colleagues published their paper on the Blanco Transition Fault Zone. Researchers at Oregon State University reported that 600 earthquake swarms occurred in just 10 days.
As for the neighboring Cascadia subduction zone, residents are forgiven for paying attention:
"Oregon is likely to have an earthquake of magnitude 9.0 or more caused by the Cascadia subduction zone and the resulting tsunamis as high as 100 feet, which will affect coastal areas," the Oregon Office of Emergency Affairs said.
The agency added: “At present, scientists predict that in the next 50 years, the probability of a major earthquake of magnitude 7.1 or higher on this fault zone is about 37%.”
A version of this story originally appeared in the morning version of the live blog.
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