Subsurface and surface motion measurements were made on six underground nuclear detonations in the Oak Springs tuff of Nevada Test Site in Operation Hardtack II: Shots Mars (∼13 tons), Tamalpais (∼77 tons), Neptune (∼115 tons), Logan (∼5 kt), Evans (∼30 tons), and Blanca (∼19 kt). Free‐field peak radial acceleration decreased as the inverse third or fourth power of slant range, as for Rainier. Particle velocities attenuated at a rate between the inverse square and inverse cube. Maximum radial and tangential subsurface stress varied as the inverse cube of radial range. Observed peak strain suggested attenuation at a rate between inverse cube and inverse square of range. Maximum upheaval at Blanca surface zero was about 25.5 feet; ∼2.5 feet at 750 feet radial range; and 1.5 feet at 910 feet. Reed gage spectra indicated a shift of maximum energy to lower frequencies with increasing ground range. All components of surface acceleration followed an empirical equation of the form
All components of surface displacement did not follow a comparable relationship. Displacement is more precisely predicted than acceleration. The velocity of the tuff was determined to be 6200 ft/sec, with the velocity of the underlying dolomite 11,700 ft/sec. If a two‐layer model for the crust beneath the Nevada Test Site is assumed, appropriate values for the thicknesses and velocities are 24 km and 5.69 km/sec for the top layer, and 36 km and 7.65 km/sec for the intermediate layer. The top of the mantle beginning at a depth of 60 km has a velocity of 8.12 km/sec and dips eastward.