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Beneath the waters of the northwestern United States, a giant fault has been accumulating tension for centuries. Now, scientists have discovered a network of hidden conduits that could help explain how one of the planet's most dangerous seismic zones behaves. What did they find? Will there be a major earthquake soon?
The research, published in the journal Science, identified conduits within the Cascadia subduction zone through which hot fluids circulate, a process that could weaken the fault and modify how accumulated tension is eventually released.
This subduction zone is a fault approximately 1,127 kilometers long that extends from northern California to British Columbia, Canada. There, the Juan de Fuca plate advances eastward at about 4 centimeters per year and slowly slides beneath the North American plate.
This tectonic interaction makes Cascadia one of the regions with the highest seismic potential in North America, with the capacity to generate earthquakes of up to 9.0 magnitude!
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In fact, there are records of an earthquake of this magnitude in that zone in 1700, which was named a megathrust.
The researchers detected "highways" or channels within the fault that allow for the displacement of fluids. These hot liquids, composed mainly of water with dissolved minerals and gases, are generated during episodes known as tremor and slip, where the plates move slowly without causing the type of sudden earthquake perceptible to humans.
That movement opens pathways through which fluids can travel to the seafloor and, at the same time, contribute to the weakening of the zone.
To detect this behavior, the scientists used information from the Regional Cabled Array, an underwater observatory composed of more than 550 miles of electro-optical cables and instruments installed off the coasts of Washington and Oregon.
The network allowed for the analysis of seismic signals and the detection of tension accumulating especially in the northern part of Cascadia. Researchers believe that a rupture in that area could behave differently than in the central sector and have the potential to generate higher-magnitude events in the future.
Historical precedent increases the concern. Scientists believe that the last major megathrust earthquake in Cascadia occurred in January 1700.
In addition to these data, the United States Geological Survey (USGS) estimated that there is between a 10% and 15% probability of an earthquake of this type occurring in the Pacific Northwest during the coming decades.
An underwater rupture might not be felt strongly on land, but it would have the capacity to generate a tsunami. The uncertainty regarding how different segments of the fault might rupture continues to make precise risk assessment difficult.
In addition to these findings, in 2021, a group of researchers also collected images of the Juan de Fuca plate that showed large fractures and a section that had sunk more than 4.8 kilometers, signs that a portion of this subduction zone could be in the process of disappearing, but not in the short term.
[Publicidad]