Seismic reflection profiling: essential geophysical data for Yucca mountain, Nevada

Yucca Mountain, Nevada, consists of a thick sequence of ashflow tuffs and lavas fractured into intact blocks with east-dipping strata, marginal broken zones characterized by dense faulting and brecciation, and intervening down-to-the-west fault zones with locally atypical west-dipping strata. Uncertainty in the structural setting of Yucca Mountain has resulted in multiple interpretations of the role and style of faulting. One interpretation describes steep normal faulting extending to seismogenic depth (10 to 15 km), and an alternate explanation suggests listric faults and a major low-angle detachment between the Tertiary volcanic sequence and the underlying Paleozoic rocks. Resolution of the deep geology is critical to evaluations of the potential tectonic and hydrologic hazards of the site. Seismic reflection profiling will provide essential data for defining the subsurface geometry of Yucca Mountain and for distinguishing between alternate interpretations of the structure of the mountain.