® r L1IOS& GroundAcqeleretioqns Pertinent measurements were taken by Sandia Corporation, Project 6.5 “Ground Motion, Saisaic”", and later through measurements of the orater. FE Cox of Sandia reports only amall earth accelerations at Ingedi. Considerable conjecture arosefrom the possibility of a structural collapee of the atoll) on MIKE shot, because geologic investigations by LASL (H.X, Stephenson) and Scripps Inetitute bad shown the rock structure to be weak; @ structural. collapse might have resulted in a tsunane of destructive magnitude. A rough quantitative prediction wes contained in a manoranium, "042 Preesures and Soergy Transfer on Mike Shot", October 10, 1952, Porsel to William E. Ogio, from vhich one expected a crater approximately 10 neters deep for 5 Mf or adout 14 metera for a 12 NF explosion, assuming » geologic structure as strong as the shot island for George shot during Greenhouse. Tt aleo showed the smali, possibility of breaking the rock structure to depths Like 300 meters, which might then subside into the oceaa, but not of serious consequence. BEST AVAILABLE COPY Mo large scale failure of the atoll occurred. A preliminary serial sur- voy waa made by Ogle just after shot time) he reports isolated turbid regions of water at distances great enough to suggest the "squeezing cut" of sand through fissures in the cereal sheath of the atoll. An serial survey two days later by Forsel and Reines suggested thet the crater was still sifting because sharp demrcations of turbid water ware still visible, which long since should have 4iffused away if they had started at sero time. The crater sppeared to be 4500 feet across. On the cosan side, the original reef had extended about . h000 feet from the shot islands no chancel was broken through between ocean and s lagoon. ‘The reef’ saterial is markedly different now than before the shot, as in the lip of @ ground crater, but here it bee been broken up by wave action. ,