Overview
- On Sept. 10, 2025 a magnitude 4.1 quake near Maeser, Utah was traced to about 68 kilometers depth and described by researchers as an archetypal continental mantle event.
- Researchers at the University of Utah reanalyzed archived seismograms and confirmed nine continental mantle earthquakes, including a Feb. 24, 1979 Randolph event located near 90 kilometers depth.
- These deep events occur without foreshocks or aftershocks, cluster along the western edge of the Wyoming Craton, and are found in unusually hot upper-mantle conditions.
- Authors propose mantle flow diverted around the craton's thick lithospheric keel concentrates strain and stress, a process whose ability to set an upper limit on quake size is not yet known.
- The findings appear in peer-reviewed journals and rely on long-term seismic archives and agency support, and researchers say more study is needed to determine whether these deep quakes pose a surface hazard.