Chapter |
INTRODUCTION
1.1
OBJECTIVE
The objective of this project was to measure the physical characteristics (radius, depth,
and average profile) of craters produced by nuclear detonations. Data were gathered from
Shots Lacrosse, Zuni, Seminole, Mohawk, and Tewa.
Although all were termed “surface”
bursts, the burst elevations actually varied between a 300-foot tower to what may be con~
sidered a subsurface burst. It was a further objective of this project to correlate the data
obtained with results from previous “surface” bursts at the Eniwetok Proving Ground
(EPG) and pertinent TM 23-200 curves.
1.2
BACKGROUND
Measurements of the apparent crater radius and depth for surface shots at the EPG had
been made during Operations Greenhouse, Ivy, and Castle (References 1, 2, and 3). Aerial
photography techniques were used in these instances to obtain data on crater radius, and
fathometer techniques were used during Castle to obtain depth measurements. Since these
operations, no new techniques have been developed for the more-refined measurement of
crater characteristics, even though more-accurate determination of the depth and profile
of a water-filled crater is desirable. The aerial-mapping technique provides ample accuracy for the determination of the crater radius, since it provides data at early times
after the burst, when the contamination from radioactive fallout is extremely high.
Project personnel of the U.S. Army Engineer Research and Development Laboratories
(USAERDL), Fort Belvoir, Virginia, were successful in making early time measurements
on the crater of Shot 7, Operation Teapot. Subsequent to that, Headquarters, Armed Forces
Special Weapons Project (AFSWP), requested that USAERDL submit a project proposal for
Operation Redwing to accomplish the previously outlined objectives.
1.3
THEORY
In an operation such as Redwing, where the land area available for detonation of largeyield surface bursts is small, compared with the predictable crater size, the extent of the
measurements obtainable and an understanding of their physical significance and reliability
need considerable clarification.
The “apparent crater” is that which is visible to the eye
subsequent to the completion of dynamic effects of the explosion, such as throwout and
fallout. Such a definition is not readily applicable to the geologic condition encountered at
EPG. If the sides of the crater break through to open water, considerable washing by
wave action will alter the shape of the apparent crater as strictly defined. This effect
would not be important, if it were desired only to compare these shots with others having