Earth and Planetary Science
EPS Planetary Science

Death of an Oceanic Plate

Image: Scientists on board the R/V Thomas G. Thompson recover a seismometer that had been recording earthquakes on the seafloor off the Pacific Northwest coast. Scientists used this information to confirm the presence of a tear in the Juan de Fuca tectonic plate under central Oregon.  (Photograph by William Hawley)

A hole in a subducted plate, in the mantle beneath North America, may cause volcanism and earthquakes on the surface of the Earth. Volcanism on the surface of North America appears to have been spatially coincident with a known zone of weakness on the slab for the last ~17 million years. We suggest that this hole is caused by tearing along the zone of weakness, a feature that is created when the plate is formed at the ridge. The tearing not only causes volcanism on North America but also causes deformation of the not‐yet‐subducted sections of the oceanic plate offshore. This tearing may eventually cause the plate to fragment, and what is left of the small pieces of the plate will attach to other plates nearby.

William Hawley (EPS graduate student) and Richard Allen (EPS Professor, BSL Director) present a tomographic model of the Pacific Northwest from onshore and offshore seismic data that reveals a hole in the subducted Juan de Fuca plate.

For a write-up in National Geographic about this research, click here.

Click here for the full article, The Fragmented Death of the Farallon Plate, published in Geophysical Research Letters.