Intraplate deformation and microplate tectonics of the Yellowstone hot spot and surrounding western U.S. interior

Abstract

Contemporary deformation of the Yellowstone hot spot and surrounding western United States is analyzed using tectonic microplate modeling, employing constraints from GPS observations corrected for postseismic deformation of M7+ earthquakes, fault slip rates, and earthquake focal mechanisms. We focus primarily on the kinematics of the Yellowstone hot spot and the eastern Snake River Plain volcanic field (ESRP), and secondarily on Basin‐Range and Columbia Plateau provinces. Our results reveal southwest motion of the Yellowstone Plateau, excluding localized volcanic deformation, at 0.9 ± 0.1 mm/a that decreases to 0.8 ± 0.1 mm/a in the ESRP block. The southwest to west motion of the Yellowstone‐ESRP introduces shear in the northern Rocky Mountain block, which is translating east at 0.78 ± 0.08 mm/a. There is <0.5 mm/a differential motion between the ESRP and the block at its northern boundary and none at the southern boundary. The eastern Basin‐Range block moves west at 3.0 ± 0.1 to 4.6 ± 0.1 mm/a, while velocities of the western Basin‐Range microplates rotate to a northwest direction, accompanied by a transition from normal to oblique shear deformation. Columbia Plateau block velocities are notably eastward, an effect enhanced by postseismic relaxation following the M9 1700 Cascadia subduction zone paleoearthquake. This study reveals that the overall motion of the western United States is characterized by clockwise rotation, with westward extension and northwest shear in the Basin‐Range province, northeast to east contraction in the Columbia Plateau, and southwest extension of the Yellowstone–Snake River Plain block that is driven by the high gravitational potential of the Yellowstone swell.