Proving Ground,?** Operation Jangle at Nevada Test Site,‘ and Project Mole.*:* These studies were concerned principally with underground explosions, but Project Mole, in particular, included observation of underground effects from several surface and above-surtface shots. Studies of ground motion have been a part of weapons effects programs for all nuclear tests. Data for these studies were derived principally from air (or tower) burats’~* although ont surface and one underground shot were included in Operation Jangle.''!? There is good correlation between the peak acceleration induced by local incidence of air shock and peak overpressure for air-burst weapons. This correlation probably holds true for surface and subsurface bursts also, although in the latter case the overpressure and the consequent ground motion are negligible. Acceleration induced by incidence of the air shock directly above instrumentation has a dominant vertical component. Ground-transmitted acceleration, from subsurface bursts or air-shock induction near Ground Zero, has a horizontal radial component of the same magnitude or greater than the vertical and is characterized by predominance of long-period surface waves (Rayleigh waves) at large ground ranges. Correlation of acceleration data from nuclear shots in accordance with scaling laws is hindered by the very complex nature of these data. The nonlinear nature of the mechanical properties of soll and its heterogeneity are reason enough to make scaling of notion parameters far from simple. REFERENCES 1. C. W. Lampson, Final Report Underground Explosion Effects, Office of Scientific Research and Development Report OSRD-6645, 1948. 2. Engineering Research Associates, Final Report—~-Underground Explosion Test Program — Vol. I, Soils; Vol. I, Rock, August 1952. 3. R. B. Vaile, Jr., Final Report——Surface Structure Program — Underground Explosion Tests at Dugway, Armed Forces Special WeaponsProject Report AFSWP-295, March 1952. 4. E. B. Doll and V. Salmon, Scaled HE Tests, Operation Jangle Report WT-377 (published in WT-365), April 1952. 5. R. B. Vaile, Jr., First Interim Report—-Small Explosion Tests — Phase | of Project Mole, Armed Forces Special Weapons Project Report AFSWP-288, December 1952. 6. L. M. Swift and D. C. Sachs, Second Interim Report-—Small Explosions Tests — Phase I of Project Mole, May 1954. 7. J. J. O’Connor and D. R. Powers, Lt USAR, Ground Shock Measurements, Operation Greenhouse Report WT-69, August 1951. 8. W. R. Perret, Earth Stresses and Earth Strains, Operation Tumbler-Snapper Report WT-503, Sept. 15, 1953. 9. J. S. Fischer and R. E. Reisler, Ground Acceleration Measurements, Operation Tumbler- Snapper Report WT-516, January 1953. 10. V. Salmon and S. R. Hornig, Earth Acceleration vs Time and Distance, Operation TumblerSnapper Report WT-517, February 1953. 11, E. B. Doll and V. Salmon, Ground Acceleration, Ground and Air Pressures for Under- ground Test, Operation Jangle Report WT-380 (published in WT-368), April 1952. 12. W. E. Morris et al., Ground Acceleration Measurements, Operation Jangle Report WT388 (published in WT-366), June 1952. 12