A number of scientific studies concerning geology and seismicity in the Southeast Idaho region have been conducted within the last ten years. The results of these studies, as well as some recent national seismic risk evaluations, indicate that the present Uniform Building Code (UBC) seismic risk zone classification for a major portion of the Southeast Idaho region is excessively high. The objective of the work presented herein is utilization of the scientific evidence to propose a revised UBC seismic risk zone map for Southeasten Idaho where a portion of the present seismic risk Zone 3 is revised to Zone 2. Regional geological information, including known and suspected faults, is presented. A comprehensive summary of magnitude and location of recorded regional earthquake epicenters and their relation to the proposed UBC seismic zone modification is presented. Correlation between the geology of the region and recorded seismic events with the proposed UBC zone revision is shown. A rationale, based on recognized seismic risk studies, is developed for location of the proposed UBC seismic risk zone lines. Correlation with existing national risk zones is shown and inherent conservatisms are discussed. Finally, the detailed location of the proposed revised zone lines is presented. It is noted that the revision affects Southeastern Idaho and small regions of Southwestern Montana and Northwesten Utah. (Author)

  • Supplemental Notes:
    • Proceedings of the Eighteenth Annual Engineering Geology and Soils Engineering Symposium, held at the Red Lion Inn, Boise, Idaho.
  • Corporate Authors:

    Idaho Transportation Department

    3311 W State Street, P. O. Box 7129
    Boise, ID  United States  83707-1129

    University of Idaho, Moscow

    Department of Geology and Geological Engineering
    Moscow, ID  United States  83844-3025

    Boise State University

    Department of Geology and Geophysics
    Boise, ID  United States 

    Idaho State University, Pocatello

    Department of Geology
    Pocatello, ID  United States  83201

    Idaho State University, Pocatello

    Department of Geology
    Pocatello, ID  United States  83201
  • Authors:
    • Arendts, J G
    • Gorman, V W
    • Guenzler, R C
    • Miller, L G
  • Conference:
  • Publication Date: 1980-4

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 115-143

Subject/Index Terms

Filing Info

  • Accession Number: 00334062
  • Record Type: Publication
  • Created Date: Sep 16 1981 12:00AM