In this overview map of Utah earthquakes, the dotted line marks the approximate location of the transition zone between the Basin and Range province and the Colorado Plateau and the blue rectangle indicates the study area. Historic seismic events in the study area (1900–1981, 4.5 ≤ M ≤ 6.6) from UUSS and USGS catalogs, and location of basins and ranges mentioned in the text. Horizontal purple dashed lines indicate approximate locations of Blue Ribbon (BRT) and Cove Fort (CVT) Transverse Zones (P. D. Rowley, 1998), thin black lines indicate Quaternary faults. MP: Markagunt Plateau Volcanic Field. The larger map (c) shows seismicity in the study area since 1981, ML ≥ 2.5 (UUSS).