water. For several minutes after the column reached maximum 

 height, water fell back, forming an expanding cloud of spray which 

 engulfed about half of the target array. Surrounding the base of 

 the column was a wall of foaming water several hundred feet high. 



Waves outside the water column, about 1,000 feet from the 

 center of explosion, were 80 to 100 feet in height. These waves rap- 

 idly diminished in size as they proceeded outward, the highest 

 wave reaching the beach of Bikini Island being seven feet. Waves 

 did not pass over the island, and no material damage occurred 

 there. Measurements of the underwater shock wave are not yet 

 available. There were no seismic phenomena of significant magni- 

 tude. 



The explosion produced intense radioactivity in the waters of 

 the lagoon. Radioactivity immediately after the burst is esti- 

 mated to have been the equivalent of many hundred tons of 

 radium. A few minutes exposure to this intense radiation at its 

 peak would, within a brief interval, have incapacitated human 

 beings and have resulted in their death within days or weeks. 



Great quantities of radioactive water descended upon the ships 

 from the column or were thro\\ai over them by waves. This highly 

 lethal radioactive water constituted such a hazard that after foui- 

 days it was still unsafe for inspection parties, operating within a 

 well-established safety margin, to spend any useful length of time 

 at the center of the target area or to board ships anchored there. 



As in Test "A," the array of target ships for Test "B" did not 

 represent a normal anchorage but was designed instead to obtain 

 the maximum data from a single explosion. Of the 84 ships and 

 small craft in the array, 40 were anchored within one mile and 20 

 within about one-half mile. Two major ships were sunk, the battle- 

 shijj ARKANSAS immediately and the heavy-hulled aircraft car- 

 rier SARATOGA after 71/0 hours. A landing ship, a landing craft, 

 and an oiler also sank immediately. The destroyer HUGHES, in 

 sinking condition, and the transport FALCON, badly listing, were 

 later beached. The submerged submarine APOGON was sent to the 

 bottom emitting air bubbles and fuel oil, and one to three other 

 submerged submarines are believed 16 have sunk. Five days after 

 the burst, the badly damaged Japanese battleship NAGATO sank. 

 It was found impossible immediately to assess damage to hulls, 

 power plants and machinery of the target ships because of radio- 

 active contamination. Full appraisal of damage will have to 

 await detailed survey by engineer teams. External observation 

 from a safe distance would indicate that a few additional ships 

 near the target center may have suffered some hull damage. There 



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