Rm men ; : yi : tee a a DON Tes coe pFay egy te CHAPTER 4 PREDICTION OF CRATERS 4.2 BACKGROUND The data required in regard to any specific megaton explosion for which a prediction of the crater is desired are (1) the yield, (2) the type of soil, and (3) the depth or height of burst. With this information, it is then appropriate to look at the existing evidence and measurements and to develop rational procedures for extrapolation or interpolation. The craters from explosions high above the surface are significantly different from those formed by lower explosions in that tney are depressions rather than excavations. It is believed that such craters are of relatively minor importance from a military standpoint and they are, therefore, not considered nere. AS mentioned in section 1.3, it is believed that an attempt to distinguish true from apparent craters becomes less and less realistic as larger and larger yields are considered. In tnis report, only apparent craters are considered. In previous analyses of crater data, the horizontal dimension used has sometimes veen diameter and sometimes radius, and these values have been measured sometimes from lip to lip and sometimes at the original ground level. In this report, only radius at original ground level is considered. In reviewing the existing jata from a broad point of view and with the objective of crater prediction for megaton explosions in mind, the following facts stand out: 1. Al) the data from which soils can be compared are contained in experiments involving relatively small quantities of TNT. 2. in those situations where more than one explosion has been fired under presumably identical conditions, an important scatter of the dimensions of the resulting craters is apparent.