From ridge to trench: seismic evolution of Pacific oceanic crust

Seismic waves bouncing off the seafloor are revealing how the Pacific Ocean’s crust evolves from the moment it is born at a mid-ocean ridge to the moment it disappears into a deep-sea trench. This matters because the upper oceanic crust—specifically a region called seismic layer 2—controls how fluids move through the seafloor. Those fluid fluxes influence everything from chemical cycling between the ocean and the Earth’s interior to the lubrication of faults that generate earthquakes at subduction zones. Current models of crustal evolution are coarse; they lack the detailed, continuous picture of how layer 2’s properties—its sound speed and density—change as the plate ages and travels hundreds of kilometres across the Pacific. The researcher will use a technique called downward continuation to simulate a seabed experiment from ship-towed seismic data, then combine traveltimes and waveforms to map those property changes. If successful, this work will produce the first continuous transect of crustal evolution across an entire plate. The immediate impact is fundamental: a sharper understanding of how the Earth recycles water and carbon. That knowledge feeds into better models of volcanic hazards, earthquake behaviour, and long-term climate regulation—systems that quietly shape the planet’s habitability but are rarely noticed in daily life.