Preliminary validation of geology at site for repository surface facilities, Yucca Mountain, Nevada
Boreholes and seismic refraction measurements have confirmed that the eastward dipping Tiva Canyon cap rock unit underlies much of the reference conceptual site for repository surface facilities. The style of faulting east of Exile Hill is imbricate normal, as seen elsewhere at the Yucca Mountain site. The alluvial cover ranges in thickness from zero at Exile Hill to 27 m at a point some 500 m east of Exile Hill. In situ primary wave velocities (Vp) average about 1 km/sec in alluvium and 1.4 km/sec in tuff - relatively low values for both. The range and overlap of values virtually precludes using velocity to distinguish between the two; consequently, structure is difficult to discern by seismic techniques. The information gained confirms the earlier conclusion that the low-angle alluvial wedge and low acoustic impedance contrast would not significantly amplify incoming seismic motion. The investigations did not establish whether bedrock faults penetrate the overlying alluvium. The information gained does not indicate that there are subsurface conditions that would adversely impact on site suitability; design options readily permit the accommodation of existing conditions at the site. Trenching investigations will be needed to verify that the location of the waste-handling facilities will not be subjected to surface rupture by faulting.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 60025
- Report Number(s):
- SAND-85-0815; ON: DE87003082
- Resource Relation:
- Other Information: PBD: Nov 1986
- Country of Publication:
- United States
- Language:
- English
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