In a breakthrough study, researchers have identified a rare geological phenomenon under the Pacific Ocean — one of Earth’s tectonic plates is breaking apart beneath another. This slow, deep process is reshaping how scientists understand Earth’s crust and plate collapse’s long-term impact.
The findings come from a team led by Brandon Shuck, a geologist at Louisiana State University. The group closely examined a region off the coast of Vancouver Island, where two oceanic plates — the Juan de Fuca and Explorer — are slowly sliding under the North American plate. This type of movement, known as subduction, plays a major role in shaping Earth’s surface, driving earthquakes, volcanic activity, and the movement of continents.
For the first time, scientists have caught detailed evidence showing one of these sinking plates physically falling apart — a process that forms smaller sections called microplates. This marks a rare opportunity to observe the breakup of a tectonic plate in real time.
Signs of a deep crustal breakdown
Using earthquake data and specialized imaging tools, researchers discovered deep cracks running through the subducting plates. These cracks suggest the structure is weakening and beginning to split apart — something that was long suspected but never directly observed.
Shuck compared the process to a train gradually losing cars, one by one, rather than crashing all at once. As the plate weakens, the downward force it exerts also decreases. Over time, this could stop the entire subduction process in that region.
This discovery is more than just a scientific milestone — it also has practical implications. Even though the breakdown happens over millions of years, regions around it, including the Pacific Northwest, remain highly vulnerable to large earthquakes and tsunamis. Better understanding how the crust changes deep below can help scientists refine future hazard forecasts and improve preparation efforts for natural disasters.
Past events may help explain today’s activity
This new evidence also helps make sense of unusual features in North America’s geological record. The study points to the long-ago breakup of another tectonic plate — the Farallon — which may have caused similar cracks and microplates beneath the continent. These fractures could have allowed molten rock to rise toward the surface, fueling volcanic activity in areas such as Yellowstone and the Cascade Mountains.
What puzzled scientists for years was how magma could reach the surface through such thick crust. Seismic readings from the West Coast show that some sections of the crust are nearly twice as thick as normal. According to this new model, broken plates and deep faults offer openings for magma to rise, even through dense rock layers.
The full findings are published in the journal Science Advances under the title Slab tearing and segmented subduction termination driven by transform tectonics. The study brings fresh insight into how the Earth’s interior behaves and why understanding it remains key to anticipating future geological risks.