Utah's Hidden Mantle Quakes Rewrite Deep-Earth Tectonics

A previously mysterious 1979 Utah quake—deep beneath the crust at about 55 miles down—kicks off new research identifying eight later deep earthquakes in the upper mantle near the Wyoming Craton. Scientists say these mantle quakes are archetypal continental mantle events driven by slow mantle flow around cratonic roots, lack foreshocks/aftershocks, and illustrate a tectonic regime at extreme depths that differs from crustal earthquakes.