for low-frequency sound waves. Some success had been achieved during both Greenhouse and Ivy in detecting SOFAR signals transmitted through the water. Relative yields were fairly well established from signals received during Greenhouse at one of the detecting stations. It was planned to again activate these remote stations for Castle to make special observations of acoustic pressure signals of the SOFAR type, to add to the knowledge of underwater sound propagation, and to investigate the possibility of determining yields. Shots 2, 4, 5, and 6 were monitored by detecting stations located on the California coast and at Bermuda. TABLE 2.4 No clear-cut signals were recorded which could be attributed to SUMMARY OF PRESSURE-TIME DATA, SHOT 5 Depth, ft: Channel: 50 i Buoy D3, 9,300-ft Distance 100 100 2 3 100 4 Buoy Al, 16,100-ft _.. Distance 40 40 a5 3 3 6 Bive Box 0 9 9 Q 2.14 _ 2.08 Pressure Arrival 0.97 0.97 0.96 0.96 1.77 _ 1.467 Pressure A, pai Time, sec 19.27 1.06 18.2 1.06 16.3 1.05 17.25 1.06 17.4 1.85 _ _ 24.2 1.78 Pressure B, pai Time, sec 32.7 1.36 84.3 1.37 84.5 1.36 845 1.36 —28.9 1.89 _ _ -35.6 1.838 Pressure C, psi 24.2 from Zero Time, sec —74.7 ~66.6 — 36.6 14.5 —_ Time, sec 1.40 1.40 1.39 1.40 1.44 _ 1.89 Pressure D, pai 88.4 78 12.2 76.1 18.78 _ 25.3 Time, sec 1.64* 1.65* 1.64¢ 1.64* 2.37 — 2.30 _ _ _ _ 32 _ 20 Pressure E, psi Time, sec _ —_ —62 _ —_ 4.90% Gage PE PE PE PE PE Amplifier log lin lint logt log _ 431° Wiancko! Witeancko _ _ “Air blast, based on arrival time. {Same gauge. f Equipment tnoperative. sources at either Bikini or Eniwetok. It is concluded that the position of the shots inside the lagoon and on the atoll rim was such as to preclude coupling of energy into the SOFAR channel in the frequency range for which instruments were available. Another factor which might have prevented reception at the California stations was the presence of shoal areas between the Bikini atoll and the coast along the most likely path of travel. 2.7 SURFACE WATER WAVES The effects of water waves resulting from megaton-yield detonations at the aurface could have military significance for (1) generation of waves in harbors causing damage to secured. vessela, docks, shore installations, etc. and (2) long-range propagation of tsunami-like waves from a source over deep water, which could produce serious damage over extensive coastal areas. The only previous full-scale data on water waves generated from a megaton surface burst had been obtained from Ivy Mike. No measurable waves were produced in the central region of the detonation, yet waves which were of measurable amplitude were observed at a range greater than four miles. These waves increased in height out to a 38