Overview
- A University of Utah team published a peer‑reviewed study that confirms at least nine earthquakes originate in the continental mantle, and it includes the Sept. 10, 2025 Maeser quake as an archetype.
- The earliest event in the set dates to Feb. 24, 1979 near Randolph and was reanalyzed as originating about 90 kilometers deep, while the 2025 Maeser event was located near 68 kilometers depth, more than 20 km beneath the Moho.
- These continental mantle earthquakes, or CMEs, occur without foreshocks or aftershocks and happen in mantle conditions where rock is usually too hot and soft for brittle failure.
- The lead hypothesis is that ancient, deep lithospheric keels in the Wyoming Craton divert mantle flow and concentrate strain at their edges, but the physical rupture mechanism and limits on event size remain unknown.
- Because CMEs do not map to surface faults, researchers say current fault‑based methods cannot bound their maximum size and they call for more targeted seismic monitoring and modeling to assess hazard implications for nearby communities.