The mystery of Utah's deep quakes June 3, 2026 U seismologists are learning what continental mantle earthquakes, occurring far below Earth's crust, reveal about what lies beneath northeast Utah and southwest Wyoming. In the early morning hours of Feb. 24, 1979, the University of Utah Seismograph Stations recorded the quake under Randolph, a Utah town near the Idaho and Wyoming borders. No one reported feeling the quake, despite its magnitude 3.8 heft, and the accompanying seismic data didn’t...