Preliminary Assessment of Fault Rupture Hazard at the Yucca Mountain Site Based on Expert Judgement

by Kevin J. Coppersmith, Geomatrix Consultants, Inc, San Francisco, United States,
Robert R. Youngs, Geomatrix Consultants, Inc, San Francisco, United States,
Roseanne C. Perman, Geomatrix Consultants, Inc, San Francisco, United States,
Robert A. Shaw, Geomatrix Consultants, Inc, San Francisco, United States,

Document Type: Proceeding Paper

Part of: High Level Radioactive Waste Management 1993


The judgments of seven earth science experts were elicited to quantify the uncertainties associated with the likelihood of fault displacement through the proposed repository at Yucca Mountain during the 10,000 year post-closure period. Each expert identified one or more approaches to modeling fault rupture hazard, regional tectonic models, locations of sources of fault displacement, maximum earthquake magnitudes or maximum coseismic displacement for each source, the likelihood of fault rupture through the repository, and the amount of displacement. The experts generally identified two basic approaches to assessing the hazard: first estimating the location and probability of earthquake occurrence and then the associated fault displacements; and considering only the location and probability of fault displacement directly. A wide variety of tectonic models were some level of credibility, ranging from high-angle planar fault to detachments separating strike-slip faults at depth from normal faults in the shallow crust. Recently acquired geologic data were relied on heavily to estimate the size of past displacements and their recurrence rates. Uncertainties were estimated for each component of the experts' models and the aggregated results are expressed as a probability distribution on the annual frequency of canister failure.

Subject Headings: Occupational safety | Probability | Site investigation | Uncertainty principles | Earthquakes | Radioactive wastes | Waste sites | Earthquake magnitude scale | Nevada | United States

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