Active faults pose two kinds of hazards that require evaluation by engineering geologists: (1) ground rupture that damages or destroys structures built across the fault; (2) seismic shaking that occurs during earthquakes. Usually hazard analysis of active faulting has dealt with these two problems as one. However, active faults in the Ojai Valley, western Transverse Ranges, southern California are associated with ground rupture of Holocene colluvium and soil but project along bedding surfaces into the axis of an underlying syncline. These faults do not cut across structure nor reach rocks of sufficient strength to produce moderate or large earthquakes. Hazard of seismic shaking is therefore considered to be minimal while ground rupture is significant. Similar types of faults, from an earthquake hazard perspective, include tensional faults along the crest of an anticline, faults due to surface subsidence and faults related to large landslides. It is not sufficient for engineering purposes to evaluate only the activity of a fault. A given fault must be analyzed in a geotechnical evaluation for its relationship to local geologic structure so that ground rupture and seismic shaking can be considered separately. (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:
    • CLARK, M N
  • Conference:
  • Publication Date: 1980-4

Media Info

  • Features: Figures; References;
  • Pagination: p. 83-96

Subject/Index Terms

Filing Info

  • Accession Number: 00334060
  • Record Type: Publication
  • Created Date: Sep 16 1981 12:00AM