Anomalous Strain Accumulation in the Yucca Mountain Area, Nevada

Abstract

Global Positioning System (GPS) surveys from 1991 to 1997 near Yucca Mountain, Nevada, indicate west-northwest crustal elongation at a rate of 1.7 ± 0.3 millimeters per year (1σ) over 34 kilometers, or 50 ± 9 nanostrain per year. Global Positioning System and trilateration surveys from 1983 to 1997 on a 14-kilometer baseline across the proposed repository site for high-level radioactive waste indicate that the crust extended by 0.7 to 0.9 ± 0.2 millimeter per year (50 to 64 ± 14 nanostrain per year), depending on the coseismic effect of the M _s 5.4 1992 Little Skull Mountain earthquake. These strain rates are at least an order of magnitude higher than would be predicted from the Quaternary volcanic and tectonic history of the area.