Pahute Mesa
Pahute Mesa is one of four major nuclear test regions within the Nevada National Security Site (NNSS). It occupies 243 square miles (630 km2) in the northwest corner of the NNSS in Nevada. The eastern section is known as Area 19 and the western section as Area 20.
The Partial Test Ban Treaty of 1963 banned atmospheric nuclear testing. This led to a requirement for an underground test area that could accommodate higher yield tests than Yucca Flat.
Pahute Mesa was seen as ideal due to its geology and distance of over 160 kilometres (99 mi) from Las Vegas. Holes can be drilled to a depth of more than 1,370 metres (4,490 ft). This allows tests in the megaton range to be fully contained with minimal ground motion being felt in Las Vegas.
Pahute Mesa was thus incorporated into the boundary of the NNSS in late 1963 under an agreement between the United States Atomic Energy Commission and the U.S. Air Force.
Pahute Mesa is part of the Tonopah Basin and includes the Silent Canyon caldera complex of the Southwest Nevada volcanic field.
Rugged terrain features and harsh winter conditions make year-round operations difficult.
A total of 85 nuclear tests were conducted in Pahute Mesa between 1965 and 1992. Three of them—Boxcar, Benham and Handley—had a yield of over one megaton. Three tests were conducted as part of operation Plowshare and one as part of Vela Uniform.
In 1988, as a prelude to the signing of the protocols to the Threshold Test Ban Treaty and the Peaceful Nuclear Explosions Treaty, the United States and the Soviet Union conducted two joint tests employing proposed treaty verification techniques. The first was Kearsarge, conducted in Area 19 of the NNSS, the second Shagan, conducted at the Semipalatinsk Test Site.
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