Fluids in Earth’s interior play a fundamental role in myriad tectonic and magmatic processes, yet constraining their distribution is challenging. The largest transfers of volatiles and elements between Earth’s surface and deep interior occur at plate margins and above mantle plumes—regions that also host the planet’s most destructive earthquakes and volcanic eruptions. Because many of these systems lie beneath the ocean, direct observations are limited. Electromagnetic (EM) geophysical methods provide one of the few tools capable of imaging fluids and magmas at depth, and recent advances now enable offshore EM imaging at regional scales.

In this seminar, I present results from active seagoing projects led by the Electromagnetic Geophysics Laboratory (EGL) that image subseafloor fluids and magmas and their impacts on two processes: (1) subduction zone earthquakes and (2) plume-tectonic interactions. First, I show results from EGL imaging surveys at the New Zealand and Alaska–Aleutian subduction margins, which reveal the distribution of fluids along the plate interface and its implications for fault locking and earthquake hazards. 

Next, we tour the eastern equatorial Pacific seafloor to explore the structure of the lithosphere and asthenosphere. By combining thermodynamically coupled Bayesian inversion of EM data with geophysical, geochemical, and drilling observations, I unravel the magmatic history of the Cocos plate over the past 20 million years. I end by highlighting a new marine survey that will image the mantle structure in the region.

*Refreshments: 10:30 AM - 11:00 AM (Atrium)