CHAPTER 4 PREDICTION OF CRATERS be BACKGROUND The,‘date 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 they 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 here. 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 this report, only apperent craters are considered.°; In previous analyses of.‘etater data, the horizontal dimension used has sometimes been diameter and,‘sometimes radius, and these values have been measured sometimes from “Up, to lip and sometimes at the original ground level. is considered. In this report); Sony oes at original ground level In reviewing the existing data tid a broad point of view and with the objective of crater prediction for megaton explosions in mind, the following facts stand out: — 1. All the data from which : oils ean be compared 2. In those situations where more’‘ than one explosion are contained in experinents involving relatively small quantities of TNT. ry has been fired under presumably identical conditions, an important scatter of the! dimensions of the resulting craters is apparent.: os 4L