Paleoseismology

Paleoseismology 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. 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

"This volume focuses on the continental intraplate region of the United States and provides an update and overview of documented Quaternary faulting and paleoseismic liquefaction east of the Rocky Mountains, and of the application of these results to seismic hazard and risk assessments. Contributions include papers that describe zones of newly recognized Quaternary deformation such as the East Tennessee Seismic Zone, as well as reinterpretations of well-known areas such as the New Madrid Seismic Zone. The chapters make important contributions to the recognition of earthquake sources active during the Quaternary and assess the seismic hazards posed by these sources. This volume should interest a wide range of readers from geology, seismology, hazard assessment, and emergency management"--Provided by publisher.

Field work for this paleoseismic investigation was performed in 1997 at three sites (Winter Canyon, Roundy Farm, and Deep Canyon) on the Clarkston, Junction Hills, and Wellsville faults. These faults, along with several lesser associated faults nearby, comprise the West Cache fault zone on the west side of Cache Valley. No previous paleoseismic studies had been conducted on these faults. The information reported here on the size, timing, and recurrence of surface-faulting earthquakes on the West Cache fault zone is critical to public officials, planners, and others making decisions regarding earthquake-hazard mitigation in Cache Valley and the northern Wasatch front. 23 pages + 1 plate

Field work for this paleoseismic investigation at Rock Canyon was performed in 1988. It was one of three studies conducted in the late 1980s and early 1990s to determine if the Provo segment of the Wasatch fault zone should be subdivided into three smaller segments as tentatively proposed by Machette and others on the basis of their geologic mapping. This investigation was the last of the three studies performed. Those results, combined with the results of paleoseismic investigations at American Fork Canyon and Mapleton, showed that the Wasatch fault where it passes through Utah Valley probably consists of a single, almost 70-kilometer-Iong fault segment (Machette and others, 1992). Publication of the details of the Rock Canyon study has been delayed for several years, chiefly due to the press of new job duties on the part of the investigators. The information remains important and is presented here for the use of those individuals interested in earthquake hazards and seismic-source characteristics of the Wasatch fault in Utah Valley. 21 pages + 2 plates

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

The historical and geological record indicate that the earthquake hazard in south-western British Columbia is relatively high. This bulletin presents results of a major paleoseismological investigation consisting of several related interdisciplinary studies that extend the seismic record of the region into prehistory. Three introductory sections contain background material on the region's geologic and tectonic setting, earthquake sources, historical seismicity, and research methods used. This is followed by four sections summarizing paleoseismological research on the following indicators of possible past earthquakes: sea level changes, tsunamis and their deposits, liquefaction of ground, and landslides. The final sections are concerned with seismic hazards (ground motion, ground rupture, subsidence and flooding, tsunamis and seiches, liquefaction, landslides) and analysis of risk and recurrence of earthquakes.