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Geometric models of faulting at Yucca Mountain

Conference ·
OSTI ID:139473
 [1];  [2];  [3]
  1. Southwest Research Inst., San Antonio, TX (US). Center for Nuclear Waste Regulatory Analyses
  2. Southwest Research Inst., Arlington, VA (US). Center for Nuclear Waste Regulatory Analyses
  3. Univ. of Texas, San Antonio, TX (US). Div. of Earth and Physical Sciences

Yucca Mountain, Nevada, is currently being studied as a potential site for a geologic repository of high-level radioactive waste. Alternative conceptual tectonic models are expected to be used by the US Department of Energy (DOE) to fulfill part of the requirement of 10 CFR Part 60 to describe and assess subsurface conditions, and to evaluate conditions that may be potentially favorable or adverse to effective waste isolation. Effective assessment of risk due to geologic hazards such as fault rupture, earthquake seismicity, and volcanic eruptions will involve the use of tectonic and structural geologic models of Yucca Mountain. Estimation of the effects of fault movement and associated distributed deformation on fracture patterns, and potential concomitant changes in bulk hydrogeologic properties, requires knowledge of fault geometry and displacement. Yucca Mountain is located in a tectonically active region, and has a recent geological history of extensional tectonic deformation. Geometric models of faults at Yucca Mountain, as described in this paper, suggest that individual fault segments may be curved at depth and flatten into a regional low-angle detachment fault surface at a depth of approximately 7 to 8 kms. Magnitude and recurrence of earthquake seismicity in the Great Basin region is strongly dependent on fault geometry. Discrimination between planar and listric fault styles is critical to assessment of earthquake seismic risk. The modeled fault system suggests that distributive displacement is probably characteristic of the Yucca Mountain fault system.

OSTI ID:
139473
Report Number(s):
CONF-920866--; ISBN 0-87262-945-7
Country of Publication:
United States
Language:
English