As a crude comparison, the 10.4 million tons TNT equivalent nuclear detonation on October 31, 1952 on the island of Elugelab in the Pacific left a crater of about one mile in diameter and 170 feet deep at its apex. Assuming conservatively that the crater was a right angle cone and that all of the debris was thrown into the atmosphere, i.e., none of the depression was caused by compression, it is estimated that about 15,000 million tons TNT equivalent of surface detonations would be required to eject an amount of dust into the atmosphere equivalent of Krakatoa. Following large nuclear detonations in the Pacific minor and temporary weather changes have been observed, such aslocal cloud formation sometimes with local precipitation, where the moisture conditions in the atmosphere are most favorable for this effect. Evaluation The most inclusive evaluative statements made are found in references 31 and 2. “... No. statistically significant changes in the weather during the first ten years of the atomic age have been found, yet careful physical analysis of the effects of nuclear explosions on the atmosphere must be made if we are to obtain a definite evaluation of this problem. Although it is not possible to prove that nuclear explosions have or have not influenced the weather, it is believed that such an effect is unlikely .. .” (1956). “,. although there has been much speculation about the influence of atomic testing on weather, there still appears to be no additional evidence suggesting a cause andetfect relationship .. .”’ (1960). D. GROUND MOTIONS — EARTHQUAKES Background Information A wide variety of factors determine both the ground motions and structural responses from nuclear detonations, i.e., energy yields of the detonations, distance from eround zero, depth of the shot and depth of measurement, and the nature of the ground (hard rock, ete.) “Competent” rock such as vranite couples and transmits more energy into seismic ground waves than does alluvium—a noncohesive sedimentary deposit. Although ground waves will be more rapidly absorbed in alluvium, it is possible for waves to travel vreat distances along the surface with relatively large amplitudes (amount of motion) if the alluviumis very thick. However, these surface waves die out rapidly with the depth into the ground. Because of the 27 1 + aai 4 i Cc ey amine re