4 Plateaus in the Pacific Ocean Aren't Rigid But Weak Spots Yanked Apart By Distant Force at Plate's Edge
After five decades, the theory explaining major landforms may need some refining. Here's what researchers recently found related to plate tectonics.
Plate Tectonics Theory Needs Some Refining
A new study examining four plateaus in the western Pacific Ocean reveals that these large regions aren't hard surfaces but rather weak points near the plate's edge that are being torn apart by forces far away.
"The theory's not carved in stone and we're still finding new things," said University of Toronto geophysicist Russell Pysklywec, who co-authored the study.
"We knew that geological deformations like faults happen on the continental plate interiors far from plate boundaries. But we didn't know the same thing was happening to ocean plates," added first author Erkan Gün, an earth scientist at the University of Toronto.
The study is simply an extension of decades of scientific attempts to map the rough terrain of the ocean floor. Scientists have been revising their understanding of the seafloor for decades.
Ocean cartographer Marie Tharp's groundbreaking work in the 1950s, employing battleship sonar data to map vast swaths of the seafloor, revealed that the ocean basins were not flat surfaces as previously thought.
Instead, the seafloor was split apart by enormous mountains and chasm-like pits, none bigger than the Mid-Atlantic Ridge that Tharp found and is today acknowledged as the world's largest mountain range, dividing the Atlantic Ocean in half.
Their investigation was restricted to these four plateaus in the western Pacific Ocean, where data were available due to the difficulties in scanning the seafloor.
The distance between the nearest plate border and the oceanic plateaus ranges from hundreds to thousands of kilometers. However, Gün and associates discovered that the plateaus had similar magmatic and deformational characteristics, indicating that pull forces are tearing them apart along the margin of the Pacific plate, where slabs are subducting beneath other plates.
The researchers' fault lines, or ruptures, typically run parallel to the nearest trench. To better understand the tectonic plate movements, the researchers additionally modeled four hypothetical plateaus between 750 and 1,500 kilometers (466 to 932 miles) from the closest subduction zone.
The fault lines, or ruptures, typically run parallel to the nearest trench. These hypothetical plateaus were stretched over millions of years and thinned more on the side closest to the trench, regardless of their distance from the plate edge.
"It was thought that because the sub-oceanic plateaus are thicker, they should be stronger," Gün said. "But our models and seismic data show it's actually the opposite: the plateaus are weaker."
What Is Plate Tectonics?
Plate tectonics is a scientific theory explaining how Earth's underground movements give rise to significant landforms. The hypothesis, which gained traction in the 1960s, revolutionized the Earth sciences, presenting various phenomena, such as earthquakes, volcanoes, and mountain-building activities.
According to plate tectonics, the crust and upper mantle, which comprise Earth's outermost layer, are divided into massive rocky plates. The asthenosphere is a partially molten layer of rock that sits atop these plates.
The asthenosphere and lithospheric convection cause the plates to move apart at varying speeds, from two to fifteen centimeters (one to six inches) annually. Numerous distinct geological structures, like the San Andreas Fault in California, the East African Rift, and the Himalayan mountain range in Asia, result from this interaction between tectonic plates.
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