The South Fork Dry Creek and Dry Gulch sites lie within a few hundred meters of each other in the southeastern part of the Salt Lake Valley, and together provide the only location on the heavily urbanized Salt Lake City segment of the Wasatch fault zone where it is possible to develop a complete surface-faulting chronology for the segment since middle Holocene time (the past 6,000 years). Investigations at the two sites took place intermittently between 1985 and 1995 as permission was obtained to trench more and more of the scarps within the broad fault zone. The new information reported here on the size, timing, and especially recurrence of surface-faulting earthquakes on the Salt Lake City segment shows that the earthquake hazard presented by this segment of the Wasatch fault is greater than previously thought. Such information is vital to public officials, planners, and others making decisions regarding earthquake-hazard mitigation. 22 pages + 1 plate

A beautifully designed and easy to understand publication discussing the geologic history of the Wasatch Fault and possible dangers it poses to anyone living nearby. This is a perfect introduction to the fault for anyone of all ages.

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.

The two reports in this Special Study provide critical geologic and paleoseismic information on the Oquirrh fault zone, a Quaternary fault in eastern Tooele County, west-central Utah. The Oquirrh fault zone has long been recognized as a potential source of large earthquakes which could affect military and hazardous waste facilities, nearby towns, and populous areas of the more distant central Wasatch Front. 64 pages + 2 plates

Paleoseismology (the study of "ancient" earthquakes) has become an important component of seismic risk analysis, which is mandated for nuclear power plants, dams, waste repositories, and other critical structures. This book is the first in the English language to be devoted solely to paleoseismology. It summarizes the development of the field from the 1960s to the present, encompassing material that is currently widely dispersed in journal articles. The 10 chapters included in this text span the entire range of techniques currently used in paleoseismic reconstruction, and are contributed by active practitioners at the forefront of paleoseismic research. * First book solely devoted to paleoseismology * Summarizes the development of the field from the 1960's to the present * Includes a comprehensive review of the techniques currently used in paleoseismology * Emphasizes practical methods of data collection and field studies * Covers interpretation of field data based on current theory concerning fault segmentation and recurrence cycles * Contains more than 170 line drawings and 50 photographs of paleoseismic phenomena