Geoscientists from the University of Toronto have made a breakthrough discovery that adds new dimensions to the theory of plate tectonics. Their research, published in Geophysical Research Letters, reveals that the Pacific Plate, which constitutes most of the floor of the Pacific Ocean, is being torn apart by large undersea faults. This discovery challenges long-held assumptions that oceanic plates are stable as they drift across Earth’s surface.
For years, scientists believed that oceanic plates remained mostly undamaged as they moved across the Earth’s mantle. However, the research team found evidence of significant geological deformations occurring deep within the Pacific Plate, particularly at the sub-oceanic plateaus of the Western Pacific Ring of Fire. These plateaus, which were once thought to be structurally strong due to their thickness, are now shown to be far weaker and prone to breaking apart as the Pacific Plate subducts under the Earth’s surface.
The Tearing of the Pacific Plate
The researchers focused on four key plateaus in the western Pacific: the Ontong Java, Shatsky, Hess, and Manihiki plateaus. By analyzing data from supercomputer models and past seismic studies, the team discovered large faults within these undersea plateaus. These faults are a result of the immense forces pulling the Pacific Plate westward, causing it to tear apart as it moves towards subduction zones.
Erkan Gün, a postdoctoral fellow at the University of Toronto, explained:
“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.”
As the Pacific Plate moves westward and begins to sink into the Earth’s mantle, the forces exerted on the plate are so strong that they begin to tear the oceanic crust apart. The faults found in this study are evidence of these forces in action, challenging the previous assumption that oceanic plates remain undisturbed as they travel across the Earth’s surface.
Rethinking Oceanic Plate Stability
One of the most surprising findings of the study was that the oceanic plateaus—once considered strong due to their thickness—are actually the weakest parts of the plate. These areas are particularly prone to tearing as the subduction zones, such as those stretching from Japan to New Zealand, pull the plate down into the mantle. Russell Pysklywec, a professor in the Department of Earth Sciences at the University of Toronto, pointed out:
“What we’re doing is refining plate tectonics — the theory that describes how our planet works — and showing those plates really aren’t as pristine as we previously thought.”
The new model suggests that the force pulling the plate is not uniform across the ocean plate, and areas where plateaus are located are more susceptible to tearing due to their composition. This finding could have implications for our understanding of seismic activity and volcanism in these regions, potentially linking these faults to volcanic events in the past.
Implications for Seismic Activity and Volcanism
The researchers speculate that the tearing of the Pacific Plate could be linked to past volcanic activity in these regions. Gün noted:
“There is evidence that volcanism occurred at these sites in the past as a result of this type of plate damage — perhaps episodically or continuously — but it isn’t clear if that’s happening now.”
Although the data from this study does not provide a definitive answer, it opens the door for further exploration of the relationship between plate tectonics, volcanic activity, and seismic events in the Pacific region. As many of the plateaus are located thousands of meters below the ocean’s surface, more data collection is needed to fully understand the ongoing dynamics of these oceanic faults.
A New Era for Plate Tectonics
This discovery adds a new layer of complexity to the long-established theory of plate tectonics. The new findings highlight that, contrary to what was previously thought, oceanic plates are not simply rigid, stable structures. Instead, they are dynamic, constantly evolving, and subject to forces that cause them to tear and shift in ways that are still not fully understood.
Pysklywec concluded:
“Now we know this fault damage is tearing apart the centre of an ocean plate—and this could be linked to seismic activity and volcanism.”
The study emphasizes that while the theory of plate tectonics has been refined over decades, there are still significant mysteries about how Earth’s plates interact and evolve. These discoveries not only reshape our understanding of the Pacific Plate but also provide valuable insights into the processes shaping the Earth’s surface.
