By: W. R. Lund, T. R. Knudsen, and G. S. Vice
This Utah Geological Survey Special Study, Paleoseismic Investigation of the Northern Weber Segment of the Wasatch Fault Zone at the Rice Creek Trench Site, North Ogden, Utah, is the eighteenth report in the Paleoseismology of Utah series. This series makes the results of paleoseismic investigations in Utah available to geoscientists, engineers, planners, public officials, and the general public. These studies provide critical information regarding paleoearthquake parameters such as earthquake timing, recurrence, displacement, slip rate, fault geometry, and segmentation, which can be used to characterize potential seismic sources and evaluate the long-term seismic hazard of Utahâ€™s Quaternary faults.
This report presents the results of a study partially funded through the National Earthquake Hazards Reduction Program to characterize the relative level of activity of the Sevier fault in southwestern Utah. The Sevier/Toroweap fault trends generally north-south through southwestern Utah and northern Arizona; by convention the fault is known as the Sevier fault in Utah and the Toroweap fault in Arizona. Approximately 108 kilometers of the 250-kilometer-long fault are in Utah. This study focused on the Utah portion of the fault and involved aerial-photograph analysis, field reconnaissance, detailed mapping of selected areas along the fault, and new major- and trace-element geochemical analyses and 40Ar/39Ar radiometric ages for volcanic rocks displaced by the fault. Determining paleoseismic parameters for the Sevier fault is important because they help the Utah Geological Survey assess the level of seismic hazard presented by the fault to southwestern Utah, and assist the U.S. Geological Survey in updating the Quaternary Fault and Fold Database of the United States and evaluating the Sevier faultâ€™s significance to the National Seismic Hazard Maps.
Pages: 27 p. + 4 p. appendix
Location: Garfield County and Kane County