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California is home to more than 500 volcanic vents and is home to seismic activity in the northwestern United States. The sunny state of the United States is at the top of a seismically active zone where the North American plate is constantly rubbing against the Pacific plate. The area is known as the shear zone in eastern California, where the so-called San Andreas fault line forms the boundary between the two plates. But just northeast of California lies another source of seismicity and volcanism that affects the geology of California and the neighboring state of Oregon.
The so-called Juan de Fuca plaque is just north of California and is undergoing subduction or passing under North America.
According to researchers at the University of California at Berkley, the ocean plate split in half, triggering activity on the mainland.
The theory was presented on July 3 in the journal Geophysical Research Letters by Berkeley University geologists William Hawley and Richard Allen.
The researchers wrote in their study: "A hole in a subducted plate, in the mantle under North America, can cause volcanism and earthquakes on the surface of the Earth.
READ MORE: Will the Big One explode along the San Andreas Fault Line?
"The volcanism on the surface of North America seems to coincide spatially with a zone of weakness known on the slab for 17 million years.
"We suggest that this hole is caused by a tear along the area of weakness, a feature created when the plaque is formed at the crest."
The tear can lead to volcanic activity in North America, but can also distort parts of the oceanic offshore plate.
Over time, the researchers announced that the plate would collapse and that the debris would merge with neighboring plates.
In essence, Mr. Hawley said that "we are seeing the death of a plaque".
READ MORE: "Swarmageddon" of 1,000 earthquakes raises fears of mega-earthquakes
Dr. Hawley, a PhD candidate in the Earth Science and Planets Department at Berkeley, told LiveScience, "Where other people have debated whether it exists or not, we can say it's real. . "
The Juan de Fuca plate extends about 965 km (965 km) from Vancouver Island in Canada to Cape Mendocino.
The plate is completely submerged under the Pacific Ocean.
Professor Allen and Mr Hawley studied ocean plate between 2011 and 2015 by dropping seismometers at the bottom of the ocean to collect data.
READ MORE: Deep-sea fish come to the surface – is this a warning sign of earthquakes?
The data collected revealed a gap in a particular type of seismic wave in central Oregon.
The researchers concluded that the gap was created by a hole between 96.5 km and 249.4 km.
About 17 million years ago, materials expelled from this hole created volcanoes that dot the so-called High Lava Plains.
Mr. Hawley said, "The story links the tomography hole to this known weak area in a plaque and to a series of volcanic centers in Oregon and to a series of earthquakes and faults off the northern coast. from California. "
What is the Juan de Fuca plate?
The Juan de Fuca plate is a tectonic plate that extends from the Juan de Fuca Ridge in the Pacific Ocean, to the western United States and Canada.
Named after the Greek explorer of the same name, the tectonic plate is being subbed under the plate of North America.
The plaque is one of the smallest on Earth and is believed to be reminiscent of the missing Farallon plate.
In 2008, more than 600 earthquakes hit the plate over a 10-day period, about 150 miles southwest of Newport, Oregon.
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