We think this new 4D framework can explain the pattern of past scenarios where a mid-ocean ridge approaches a trench and subduction terminates and reorganizes into a transform plate boundary. It fits incredibly well with the fossil record of subduction termination along Baja California!

The transform boundary formed out of necessity due to resistance to subduction of the warm and buoyant oceanic lithosphere near the RTF triple junction. A trench-perpendicular transform can efficient fragment the incoming oceanic plate and slow its subduction. The tearing pattern is shown here:

The ephemeral transform boundary, called the Nootka Fault Zone which separates the Explorer microplate from the Juan de Fuca Plate, formed as a broad shear zone in rheology homogeneous oceanic lithosphere and progressively localized over time.

The northern oceanic slab is actively tearing apart in multiple directions — a trench-parallel tear propagating from the slab edge, and trench-perpendicular tearing along a unique transform boundary, which causes breakoff of the microplate’s slab, while allowing adjacent subduction to continue.

So what did we find? We focused this study on northern Cascadia which hosts a complex Ridge-Trench-Fault triple junction. New deep-penetrating seismic reflection images and detailed earthquake catalogs reveal the subsurface architecture and evolution during subduction termination.

🚨🚨 One of the clearest pictures of a subducting slab tearing to date? I think so, but tell me what you think! Super thrilled that our manuscript on slab tearing and subduction termination just went live in Science Advances! You can read all about it for free here: www.science.org/doi/10.1126/...

Just deleted my science twitter and made a bsky... My feed was getting full of crazy stuff, and I pretty much just want to see things about rocks, earthquakes, and fluffy dogs/cats.
Wassup?