Tectonics from Topography: Utilization of Normal Fault Bedrock Facet Slopes as a Quantitative Predictor of Slip Rate

Abstract

The rapid and cost effective prediction of seismic hazard from normal faults has long been a goal of seismologists and geologists, but to date this goal has not been achieved. Here I use measurements of the steepness of facet slopes along the Wasatch Fault Zone from central Utah to southern Idaho, in conjunction with published measurements of erosion rates and fault dip, to quantitatively predict slip rate using a recently developed geometric model of normal-fault bounded mountain front evolution. Slip rates are relatively well constrained from paleoseismic studies along the Wasatch Fault Zone, which serves as a useful test case to which the geometric model-derived values are compared. I find that the slip rates predicted from the geometric model are consistent with slip rates determined from independent paleoseismic studies. Hence, the geometric model of normal-fault bounded mountain front evolution tested here appears to be a viable method for calculating the slip rate of normal faults and allows for rapid and inexpensive determination of seismic hazard along the length of the Wasatch Fault, Utah and other similar normal faults throughout the Great Basin and the world.