Pesquisadores documented for the first time a subduction zone actively fragmenting beneath the Pacífico ocean floor. Fuca’s Juan board gradually disintegrates as it sinks beneath Norte’s América, rather than collapsing all at once. The study, published in the journal Science Advances, provides unprecedented evidence about the evolution of these gigantic geological systems and could refine scientists’ understanding of earthquake behavior in northwestern Pacífico.
Advanced Técnicas reveals active fragmentation
Equipes research used advanced seismic reflection imaging combined with earthquake data to reveal the real-time fragmentation of the plate. Data comes from the 2021 Experimento of Imagem Sísmica of Cascadia (CASIE21), carried out on board the vessel Marcus G. Langseth. Pesquisadores of Escola of Clima of Universidade Columbia, including Suzanne Carbotte and Anne Bécel, sent sound waves to the seafloor using a 15-kilometer-long network of underwater sensors. The seismic images work like an ultrasound of the interior of Terra, revealing sections of the plate fragmenting and creating complex structures at great depths.
The researchers identified several large ruptures, including a major fault where the plate sank approximately three miles. The findings show that the plate doesn’t simply sink; it breaks in a continuous and progressive process.
Características main fragmentation observed
- A 75-kilometer-long fault with variable seismic activity.
- Áreas with frequent earthquakes alternating with zones of unusual seismic silence.
- Seções from the board detaching in stages over time.
- Criação of smaller microplates and new tectonic frontiers.
Why subduction zones deactivate
Subduction Zonas moves continents, triggers large earthquakes, causes volcanic eruptions, and pulls ancient Earth crust deep into the mantle. Porém, these systems don’t last indefinitely. If they continued, continents would accumulate, oceans would disappear, and much of geological history would be erased. Scientists have been wondering for decades what causes these processes to shut down.
Brandon Shuck, Universidade Estadual assistant professor at Louisiana and lead author of the study, compared the phenomenon to a moving train. Iniciar a subduction zone requires immense effort, similar to pushing a train up a hill. Once in motion, however, it works like a train going down at full speed, impossible to stop. Shuck conducted the research as a postdoctoral researcher at Observatório of Terra Lamont-Doherty of Universidade Columbia.
Fragmentação episodic and card life cycle
The study reveals that subduction zones do not fail simultaneously. Instead, they terminate through episodic termination, a process where the plaque ruptures in stages, with different sections shedding over time. Conforme smaller pieces fall off, the larger plate loses the force that drives it downwards. Shuck explained that instead of extinguishing completely at once, the plaque progressively fragments, creating smaller microplates. The process resembles a train slowly derailing, car after car.
Quando a piece breaks off completely, it stops producing earthquakes, as the rocks do not remain together. Essas silent gaps suggest that parts of the plate have already separated and the crack is gradually expanding. Over millions of years, this gradual loss of momentum can bring the entire subduction system to a standstill. The process explains intriguing features observed in other Earth regions, such as remnants of the ancient plate of Farallon found offshore Baja California.
Implicações for future earthquakes in Pacífico
Cientistas are now investigating how these newly discovered fissures could influence future earthquakes in the region. A fundamental question is whether a large magnitude rupture could propagate through these fractures or whether the fissures would alter the way seismic energy spreads. For now, the findings do not significantly modify the overall risk in Cascadia. The region remains capable of producing earthquakes and tsunamis of great magnitude. Incorporar these new details in models will improve Pacífico’s understanding and simulation of seismic hazards in the northwest.