Scientists fear a hole in a 600-mile-long fault line in the Pacific could trigger a catastrophic earthquake that would decimate cities in the northwest United States.
The hot liquid-spewing hole is 50 miles off the Oregon shore, at the edge of the plunging fault known as the Cascadia Subduction Zone, which stretches from northern California to Canada.
This geological feature is capable of triggering a magnitude 9 earthquake in the Pacific Northwest – and the hole could be the fuel it needs.
The leak was first observed in 2015, but new analysis conducted by the University of Washington (UW) suggests the chemically distinct liquid is “default lubricant”.
This fluid allows the plates to move smoothly, but without it “stress can build up to create a damaging earthquake,” the researchers said.
The hole sits on the edge of the Cascadia subduction zone and spews a chemically distinct liquid that could be a “fault lubricant.” This fluid allows the plates to move smoothly, but without it “stress can build up and create a damaging earthquake,” the researchers said.
The team named the hole, which they describe as a hot spring, “Pythias Oasis” after the ancient Greek oracle who “prophesied” with the help of mind-altering gases from a hot spring.
“It seems equally mind-blowing to find a source of low-salinity, high-temperature, mineral-rich water flowing from the seafloor 3,280 feet below the surface off the Oregon coast,” shared the researchers in a statement.
A robotic diver discovered the hole during a 2015 survey when sonar images captured bubbles rising from the seabed.
The data showed that the source liquid originated from the plate boundary and appeared hotter than the surrounding area.
Co-author Evan Solomon, a UW associate professor of oceanography who studies the geology of the seabed, said in a statement: “They explored in this direction and what they saw was not just methane bubbles, but water coming out of the seabed like a fire hose.
“It’s something I’ve never seen and to my knowledge has never been observed before.”
Observations later determined that the leaking liquid was 16 degrees Fahrenheit warmer than the surrounding seawater and came directly from the Cascadia megathrust, where temperatures are estimated at 300 to 500 degrees Fahrenheit.
“The loss of fluid from the offshore mega-thrust interface through these strike-slip faults is significant,” the statement notes, “because it lowers fluid pressure between sediment particles and therefore increases friction between plates. oceanic and continental.
The Cascadia megathrust spans several major metropolitan areas, including Seattle and Portland, Oregon, but also affects parts of northern California and Vancouver Island in Canada.
Solomon compared the megathrust rift zone to an air hockey table
Scientists said it was the first known site of its kind and feared a mega-quake could be triggered
A robotic diver discovered the hole during a 2015 survey when sonar images captured bubbles rising from the seabed. The data showed that the source liquid originated from the plate boundary and appeared hotter than the surrounding area
A large fluid leak off central Oregon could explain why the northern part of the Cascadia subduction zone off Washington would be more tightly locked or coupled than the southern part off the US coast. Oregon, experts said.
“If the fluid pressure is high, it’s like the air is open, which means there’s less friction and the two plates can slip,” he said.
“If the fluid pressure is lower, the two plates lock together – that’s when stress can build up.”
The Cascadia subduction zone is a region where two tectonic plates collide.
The Juan de Fuca, a small oceanic plate, is pulled under the North American Plate at the top of the continental United States.
Subduction systems – where one tectonic plate slides over another – can produce the largest known earthquakes in the world. A prime example is the 2011 Tohoku earthquake which rocked Japan killing an estimated 20,000 people.
Cascadia is seismically quiet compared to other subduction zones but is not completely inactive.
Research indicates that the fault ruptured in a nine-magnitude event in 1700, about 30 times more powerful than the largest predicted earthquake in San Andreas.
Solomon said the fluid released from the fault zone is the first known site of its kind.
Observations determined that the leaking liquid was 16 degrees Fahrenheit warmer than the surrounding seawater and came directly from Cascadia’s megathrust.
The hole, which spews hot liquid, is 50 miles off the Oregon coast
However, he theorizes that similar sources could be lurking nearby but are harder to detect from the ocean surface.
A large fluid leak off central Oregon could explain why the northern part of the Cascadia subduction zone off the coast of Washington is more strongly locked or coupled than the southern part off the coast of Washington. ‘Oregon.
Co-author Deborah Kelley, professor of oceanography at UW, said: “Pythias Oasis offers a rare window into processes operating deep in the seabed, and its chemistry suggests that this fluid originates from the plate boundary. .
“This suggests that nearby faults regulate fluid pressure and megathrust slip behavior along the central Cascadia subduction zone.”
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