by the larger yield and lowerheight of burst in the case of Shot Zuni. The 1 csultant
sloughing of the rupture zone would be encouraged by severe washing by the waves created
by the explosion. ‘Vave action at the Zuni site was severe enough to wash awayall evidence of a lip if an) existed. The Mohawk crater, on the other hand, does not seem to
have undergone as -.evere washing, since the crater lip still exists.
4.4
SHOT SEMINOLE
The relationship of the burst point of this shot to the ground surface must be examined
before the crater r.:sults are compared with previous data. The nuclear device was detonated inside a 50-foot-diameter tank of water, 25 feet deep, with the center of gravity
of the charge 4.5 fet above the bottom of the tank (Figure 3.14). The least dimension to
outside air in any: irection was approximately 10 feet. This material should have provided sufficient m: ss to cause the temperature of the isothermal sphere to be reduced so
that transfers of c ergy by shock would be faster than by radiation. This probably occurs
at about 300,000 K (Figure 4.3). If we can assume that the isothermal sphere had proceeded into a shock phase before it reached the top of the water tank and that each cubic
foot of water looks like about 0.6 cubic feet of earth during the radiative transport phase,
then the energy pa-titioning of the burst may be similar to that for an underground burst
with a charge deptl: of about 12 feet. For this reason, in rcducing the crater dimensions,
the crater depth is referenced to the adjusted surface of the water in the tank. The early
growth of the isothermal sphere, when it is near an interface such as air and earth, plays
a large part in determining the energy partition of the burst between the two media. Shot
Seminole appears to be zn excellent example of this. Further evidence of the effects of
the water tank on «nergy partitioning is the fact that the radius was somewhatlarger in
the direction of the greatest thickness of water in the tank. This can be seen in Figure
3.12.
There is no information available on the depth of the water in the proximity of ground
zero nor of the postshot crater in these areas, since all surveys were made along the
lines indicated. However, it is felt that any effect on the crater due to these areas is
minor in compari..on to the effect caused by the water tank.
Again the existence of a lip may indicate the lack of complete washing, due probably
to the protection cffered the crater by the surrounding land mass. The cri ter radius then
should probably be increased by 10 percent or moreto be fully washed.
4.5
SHOT MOHAWK
This burst was on a 300-foot tower. The crater dimensions compare favorably with
predictions, as evidenced in Figures 4.1 and 4.2, although the existence of a lip may indicate that full washing did not occur and the radius should be increased by 10 percent.
4.6
SHOT TEWA
This shot was fired on a barge in approximately 20 feet of water adjacent to the
Charlie-Dog reef of Bikini Atoll. Although the bottom slopes from north to south through
ground zero (Figures 3.20 and 3.22), this variation is small when compared to charge size.
Due to the air-water and the water-ground interfaces, however, it is believed that less
energy was channeled into cratering and the radius figure given is probably low. Itis
also difficult to assume a height of burst, but it is believed that it should be between 0 and
20 feet.
This report uses 20 feet, which when scaled, should be close.
36