TEST B: UNDERWATER EXPLOSION 



SHOCK WAVES 



While the column was spurting upward, two kinds 

 of shock waves were racing outward. The underwater 

 shock wave, described on a preceding page, traveled 

 fastest, and did the greatest damage. The shock wave 

 in air was less harmful, but was extremely interesting 

 in many respects. It had, for example, a dual origin. 

 In part it was created by the very rapid expansion of 

 the fireball and column in their first instant of escape 

 from the water. The shock wave created, shaped like 

 an egg standing on end, was so intense that it showed 

 up clearly in short-exposure pictures taken from the 

 towers on Bikini Island. The concentration of air in 

 the shock wave acted like a prism and, by optical re- 

 fraction, left a clear elliptical line on the photographic 

 films. The shock wave in air was born also from the 

 fillet, the circular region surrounding the column base. 

 In the fillet area, the water was so violently hammered 

 from below that the surface of the lagoon was pushed up 

 slightly. The energy within the water could not be con- 

 strained to stay there; part of the energy leapt into 

 the air to produce an air shock wave proceeding more 

 upward than outward. 



The combination of the elliptical shock wave and 

 the upward shock wave produced a wave of remarkable 

 shape. Where the two effects joined, the shock wave 

 had a definite bend, such as occurs where the brim of 

 a hat joins the crown. The bend did not last long. As 



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