Scientists have directly observed, for the first time, the breakup of a subduction zone beneath the ocean, according to a study published in Science Advances. The findings show that tectonic plates fragment gradually into smaller sections rather than breaking apart as a single unit.
The study focuses on the Juan de Fuca Plate, located off the Pacific Northwest coast, which is subducting beneath the North American Plate. Researchers observed that instead of behaving as a solid structure, the plate is splitting into smaller segments as it descends.
Subduction zones are regions where one tectonic plate moves beneath another and are associated with earthquakes, volcanic activity, and the recycling of Earth’s crust. Previous understanding suggested that such systems could cease abruptly, but the new findings indicate a gradual process of fragmentation.
Observations were made in the Cascadia region near Vancouver Island, Canada, where scientists identified the plate breaking into distinct sections and forming microplates. The study provides direct evidence of a subduction zone undergoing a progressive breakup.
The findings are based on data from the 2021 Cascadia Seismic Imaging Experiment, which used seismic reflection techniques. Researchers transmitted sound waves into the seafloor and analyzed their վերադարձ to map subsurface structures.
The data revealed large fractures and fault lines within the plate, with segments having shifted several kilometres downward. Researchers noted that the plate has not fully separated but is moving toward that state.
The study does not indicate an immediate reduction in earthquake risk in the Cascadia region, which remains capable of generating large earthquakes and tsunamis. However, the findings may improve understanding of how seismic energy is distributed and how risk evolves over time.
Researchers stated that similar processes may be occurring in other parts of the world, offering insights into remnants of older tectonic plates and contributing to improved earthquake modelling.
