FOREWORD This report presenta the preliminary results of one of the projects participating in the military-effect programs of Operation Hardtack. Overall information about this and the other military-effect projects can be obtained from ITR-1660, the “Summary Report of the Commander, Task Unit 3.” This technical summary includes: (1) tables listing each detonation with its yield, type, environment, meteorological conditions, etc. ; (2) maps showing shot locations; (3) discussions of results by programs; (4) summaries of objectives, procedures, results, etc., for all projects; and (5) a listing of project reports for the military~effect programs.