Consensus Preferred Recurrence Interval And Vertical Slip Rate Estimates

This report presents the results of the Utah Quaternary Fault Parameters Working Group (hereafter referred to as the Working Group) review and evaluation of Utah’s Quaternary fault paleoseismic-trenching data. The purpose of the review was to (1) critically evaluate the accuracy and completeness of the paleoseismictrenching data, particularly regarding earthquake timing and displacement, (2) where the data permit, assign consensus, preferred recurrence-interval (RI) and vertical slip-rate (VSR) estimates with appropriate confidence limits to the faults/fault sections under review, and (3) identify critical gaps in the paleoseismic data and recommend where and what kinds of additional paleoseismic studies should be performed to ensure that Utah’s earthquake hazard is adequately documented and understood. It is important to note that, with the exception of the Great Salt Lake fault zone, the Working Group’s review was limited to faults/fault sections having paleoseismic-trenching data. Most Quaternary faults/fault sections in Utah have not been trenched, but many have RI and VSR estimates based on tectonic geomorphology or other non-trench-derived studies. Black and others compiled the RI and VSR data for Utah’s Quaternary faults, both those with and without trenches.

This 43-page report presents new data from the Willow Creek site that provides well-defined and narrow bounds on the times of the three youngest earthquakes on the southern strand of the Nephi segment, Wasatch Fault zone, and refines the time of the youngest earthquake to about 200 years ago. This is the youngest surface rupture on the entire Wasatch fault zone, which occurred about a century or less before European settles arrived in Utah. Two trenches at the Willow Creek site exposed three scarp-derived colluvial wedges that are evidence of three paleoearthquakes. OxCal modeling of ages from Willow Creek indicate that paleoearthquake WC1 occurred at 0.2 ± 0.1 ka, WC2 occurred at 1.2 ± 0.1 ka, and WC3 occurred at 1.9 ± 0.6 ka. Stratigraphic constraints on the time of paleoearthquake WC4 are extremely poor, so OxCal modeling only yields a broadly constrained age of 4.7 ± 1.8 ka. Results from the Willow Creek site significantly refine the times of late Holocene earthquakes on the Southern strand of the Nephi segment, and this result, when combined with a reanalysis of the stratigraphic and chronologic information from previous investigations at North Creek and Red Canyon, yield a stronger basis of correlating individual earthquakes between all three sites.

"This study (132 p., 6 pl.) assesses water quality in the aquifers in the southern Sanpete and central Sevier Valleys to determine likely sources of nitrate pollution and determine the relative age of high-nitrate water"--Back label of container.

Lake Bonneville: A Scientific Update showcases new information and interpretations about this important lake in the North American Great Basin, presenting a relatively complete summary of the evolving scientific ideas about the Pleistocene lake. A comprehensive book on Lake Bonneville has not been published since the masterpiece of G.K. Gilbert in 1890. Because of Gilbert’s work, Lake Bonneville has been the starting point for many studies of Quaternary paleolakes in many places throughout the world. Numerous journal articles, and a few books on specialized topics related to Lake Bonneville, have been published since the late 1800s, but here the editors compile the important data and perspectives of the early 21st century into a book that will be an essential reference for future generations. Scientific research on Lake Bonneville is vibrant today and will continue into the future. Makes the widespread and detailed literature on this well-known Pleistocene body of water accessible Gives expositions of the many famous and iconic landforms and deposits Contains over 300 illustrations, most in full color Contains chapters on many important topics, including stratigraphy, sedimentology, hydrology, geomorphology, geochronology, isostasy, geophysics, geochemistry, vegetation history, pollen, fishes, mammals, mountain glaciation, prehistoric humans, paleoclimate, remote sensing, and geoantiquities in the Bonneville basin

This 81 page report presents the results of a study of the Hurricane fault in Utah.

This CD contains a 33 page report, appendix, and plate. This study presents the results of fault-trench excavations near Santaquin, Utah, and includes discussion of (1) previous paleoseismic investigations on the Nephi segment, (2) the geology of the Santaquin trench site and excavations (3) paleoseismic results, including the timing of the most recent surface-faulting earthquake, fault displacement and slip rate, and surface-faulting earthquake recurrence and (4) implications for the segmentation of the southern Wasatch fault zone.