Implications about in situ stress at Yucca Mountain

Volcanic tuffs under Yucca Mountain on the Nevada Test Site (NTS) are being considered as potential media for geologic disposal of radioactive waste. Calculations in support of site evaluation, repository design, and performance assessment require accurate estimates of the in situ stresses and the variability in the stress state within Yucca Mountain. This paper uses the regional geologic studies that pertain to the stress state at the NTS, stress measurements at Yucca Mountain, and stress measurements in nearby Rainier Mesa, in conjunction with finite element calculations to estimate the in situ stresses at Yucca Mountain. Based on these data, values of lateral earth-stress coefficients (K{sub 0}) in the range 0.3 < K{sub 0} < 0.8 are reasonable for repository depths in thermomechanical analyses. 5 figs.