Paleoseismology of Utah, Volume 15: Surficial-geologic reconnaissance and scarp profiling on the Colliston and Clarkston Mountain segments of the Wasatch fault zone, Box Elder County, Utah (SS-121)
By: M. D. Hylland
The Collinston and Clarkston Mountain segments, the northernmost two segments of the Wasatch fault zone in Utah, have been active during the Quaternary Period but show no evidence of Holocene surface faulting. The only fault scarps identified on Quaternary deposits along the Collinston segment are in the area of the Coldwater Canyon reentrant, which is at the segment boundary with the Brigham City segment to the south and includes numerous scarps that resulted at least in part from Holocene Brigham City-segment ruptures. Empirical analysis of scarp-profile data obtained in this study indicates that the timing of the late Holocene most recent surface-faulting earthquake (MRE) in the segment boundary area predates the MRE timing determined in trench studies by others farther south on the Brigham City segment; this suggests the Brigham City-segment MRE identified in the trench studies did not rupture the northernmost part of the Brigham City segment.
Contains an 18-page report that summarizes a recent UGS project to characterize the relative level of activity of the Collinston and Clarkston Mountain segments of the Wasatch fault zone. The project involved geologic reconnaissance, scarp-profile measurement and analysis, and empirical analysis of relations between surface rupture length and vertical displacement. Results include estimates of the timing of most recent surface faulting for both segments and estimates of slip rate and earthquake magnitude for the Clarkston Mountain segments. The report also includes a discussion of issues related to using data from nearby Bonneville shoreline scarps to calibrate diffusion-equation models of fault-scarp age.
Pages: 18 p.
Location: Box Elder County