Overview
- The peer-reviewed study in Science Advances presents the first clear seismic-imaging evidence of an active subduction zone breaking beneath the seafloor off Vancouver Island.
- Imaging shows several large tears in the Juan de Fuca plate, including a roughly 75-kilometer rip and a major fault where the slab has dropped about five kilometers.
- Earthquake catalogs line up with the structures, with quiet stretches pointing to detached pieces and nearby active segments indicating areas that are still locked.
- The findings come from the 2021 CASIE21 survey, which used seismic reflection tools like an ultrasound and a 15-kilometer sensor array aboard the research vessel Marcus G. Langseth.
- Authors report a piece-by-piece shutdown that can spawn microplates and explain fossil fragments like Farallon remnants near Baja California, and they are now testing how these tears could limit rupture length and refine hazard and tsunami models without changing current risk levels.