Project Pre-Gondola III, Phase I, a continuation of chemical-explosive cratering experiments conducted in saturated clay-shale near Fort Peck, Montana, was designed to excavate a row crater with relatively flat side slopes. The technical programs conducted during the experiment were: (1) measurements of the apparent crater, (2) surface-motion analysis, (3) cloud-development studies, and (4) airblast measurements. (Author).

Four microbarograph stations recorded waves at a range of approximately 130 mi from a row charge of high explosives buried near optimum cratering depth. Comparison with propagations from three airburst calibration detonations showed that a source model derived from close-in data was appropriate for distant effects predictions. This model predicted that wave amplitudes from explosives at this scaled depth would be 20% of amplitudes expected for a free air burst. All amplitudes perpendicular to a row charge are proportional to the 0.7 power of the number of charges in the row.

[Describes all reports prepared from fiscal years 1962-72.]

Contents: Description of Pregondola 2 experiment; Crater measurements and ejecta studies; Surface motion measurements; Geologic and engineering properties investigations; Seismic studies; Close-in airblast; Cloud development studies; Biological monitoring.