Faultless test - 1968 Underground Atomic explosion

The Faultless test (January 19, 1968) was a calibration test conducted in a mine cavity 3,200 feet beneath the Hot Creek Valley near Tonopah, Nevada, with a yield of around 1 megaton. This test was conducted to see if the land was fit for testing a 5 megaton thermonuclear warhead for the Spartan missile. The test failed because of the large degree of faulting that resulted in the area around the test.