Operation SUN BEAM, SHOT SMALL BOY. Project Officers Report. Project 1. 9. Crater Measurements

The objectives of Project 1.9 were to obtain the dimensions of the apparent and true craters formed by the Small Boy event and to measure the permanent earth deformation occurring beyond the true crater boundary. Measurements were made of the apparent crater by aerial stereophotography and ground survey and of the true crater and subsurface zones of residual deformation by the excavation and mapping of an array of vertical, colored sand columns which were placed along one crater diameter prior to the shot. The results of the crater exploration are discussed, particularly the permanent compression of the medium beneath the true crater which was responsible for the major portion of the apparent and true crater volumes. Apparent and true crater dimensions are compared with those of previous cratering events. Extracted version of report dated 3 Mar 65.