[ ___- Announced United States Nuclear Tests -- By Date Event Name... . | Date (GCT) Location - |. . Type — Lees Purpose ... .. .:-Yield Range .. Operation Hardtack It -- Continued Colfax Unstemmed hole Radioactivity not detected off site 10/05/58 NTS Shaft Safety Experiment 5.5 tons Hidalgo 10/05/58 NTS Balloon Safety Experiment 77 tons Tamalpais Slight venting 10/08/58 NTS Tunnel WeaponsRelated 72 tons Quay 10/10/58 NTS Tower WeaponsRelated 79 tons Lea 10/13/58 NTS Balloon Weapons Related 1.4 kt Neptune Slight venting 10/14/58 NTS Tunnel Safety Experiment 115 tons Hamilton 10/15/58 NTS Tower WeaponsRelated 1.2 tons Logan No radioactive release detected 10/16/58 NTS Tunnel WeaponsRelated 5 kt Dona Ana 10/16/58 NTS Balloon WeaponsRelated 37 tons Vesta 40/17/58 NTS Surface Safety Experiment 24 tons Rio Arriba 10/18/58 NTS Tower WeaponsRelated 90 tons San Juan Unstemmed hole 10/20/58 NTS Shaft Safety Experiment Zero Socorro 10/22/58 NTS Balloon WeaponsRelated 6 kt Wrangell 10/22/58 NTS Balloon WeaponsRelated 115 tons Rushmore 10/22/58 NTS Balloon WeaponsRelated 188 tons Oberon No radioactive release detected 10/22/58 NTS Tower Safety Experiment Zero Radioactivity not detected off site Radioactivity not detected off site Fired in surface structure No radioactive release detected .