Scientists fear that a hole in a 600-mile-long fault line in the Pacific could trigger a catastrophic earthquake that would devastate cities along the northwestern US.
The vent spewing hot fluid is 50 miles off the coast of Oregon, on the border of a dipping fault known as the Cascadia Subduction Zone, which stretches from Northern California to Canada.
This geological feature is capable of unleashing a magnitude-9 earthquake in the Pacific Northwest – and the hole may be the fuel it needs.
The leak was first observed in 2015, but a new analysis led by the University of Washington (UW) suggests that the chemically strange liquid is ‘fault 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 boundary of the Cascadia Subduction Zone and is spewing a strange chemical fluid that could be a ‘fault 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 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 rising from a hot spring.
‘Finding a spring of low-salinity, high-temperature, mineral-rich water flowing from the seafloor 3,280 feet below the surface off the Oregon coast seems equally hallucinatory,’ researchers shared in a statement.
A robotic diver discovered the hole during a survey in 2015 when sonar images captured bubbles rising from the seafloor.
The data showed that the fluid from the spring was coming from the plate boundary line and appeared to be warmer than the surrounding area.
Co-author Evan Solomon, a UW associate professor of oceanography who studies seafloor geology, said in a statement: ‘They explored in that direction and what they found were not just bubbles of methane, but water coming out of the seafloor like a firehose.
‘That is something I have never seen and, to my knowledge, has never been observed before.’
Observations later determined that the leaked fluid was 16 degrees Fahrenheit warmer than the surrounding seawater and was coming directly from the Cascadia megathrust, where temperatures are estimated to be 300 to 500 degrees Fahrenheit.
‘The loss of fluid from the offshore megathrust interface through these strike-slip faults is important,’ the statement says, ‘because it lowers the fluid pressure between the sediment particles and therefore increases the friction at between oceanic and continental plates.’
The Cascadia megathrust covers several major metropolitan areas, including Seattle and Portland, Oregon, but also reaches parts of Northern California and Vancouver Island in Canada.
Solomon compared the megathrust fault zone to an air hockey table
Scientists say this is the first known site of its kind and fear a megaquake may occur
A robotic diver discovered the hole during a survey in 2015 when sonar images captured bubbles rising from the seafloor. The data showed that the fluid from the spring was coming from the plate boundary line and appeared to be warmer than the surrounding area.
A significant fluid leak in central Oregon may explain why the northern part of the Cascadia Subduction Zone, off the Washington coast, is believed to be more strongly locked, or fused, than the southern section off the Oregon coast, said the experts.
‘If the pressure of the fluid is high, it’s like the air is on, which means less friction and the two plates can slip,’ he said.
‘If the fluid pressure is lower, the two plates will lock – that’s when stress can build.’
The Cascadia subduction zone is a region where two tectonic plates collide.
The Juan de Fuca, a small oceanic plate, is being pushed beneath the North American plate over the continental US.
Subduction systems – where one tectonic plate slides over another – can produce the world’s largest known earthquakes. A prime example is the 2011 Tohoku earthquake that shook Japan, killing an estimated 20,000 people.
Cascadia is seismically quiet compared to other subduction zones but not completely inactive.
Research indicates that the fault ruptured in a magnitude nine event in 1700, about 30 times stronger than the largest predicted San Andreas earthquake.
Solomon said the fluid released from the fault zone was the first known site of its kind.
Observations determined that the leaked fluid was 16 degrees Fahrenheit warmer than the surrounding seawater and came directly from the Cascadia megathrust
The vent, spewing hot fluid, is 50 miles off the coast of Oregon
However, he speculated that similar springs may lurk nearby but are harder to see from the surface of the ocean.
A significant fluid leak in central Oregon may explain why the northern part of the Cascadia Subduction Zone, off the coast of Washington, is believed to be more tightly locked, or fused, than the southern section off the coast of Oregon.
Co-author Deborah Kelley, a UW professor of oceanography, said: ‘Pythias Oasis provides a rare window into processes operating deep on the seafloor, and its chemistry suggests that this fluid originates from near the plate boundary.
‘This suggests that nearby faults control fluid pressure and megathrust slip behavior along the central Cascadia Subduction Zone.’
