Nuclear tests: databases and other material--Johnston's Archive

Midas Myth/Milagro nuclear test, 1984

compiled by Wm. Robert Johnston
last modified 6 November 2006

Date: 15 February 1984

Location: Nevada Test Site, Nevada, USA

Type of event: accident associated with collapse pit formation from underground nuclear test


At 17:00 UT (10:00 AM local time) an underground test was conducted at Rainer Mesa in the Nevada Test Site. The test, Midas Myth or Milagro, was designed to investigate weapon effects and involved a device with yield between 0 and 20 kt (likely closer to 20 kt) in a tunnel at a depth of 361 meters. Shortly after the test technicians went to equipment trailers at ground zero. While there, the column of rock above the test collapsed 3 hours, 13 minutes after detonation, causing the surface at ground zero to collapse into a crater 113 meters across and 5 meters deep. Such collapse pit formation, while typical for underground tests, was not expected so soon after detonation in this case. The collapse caused injuries to 15 personnel, one of whom later died of his injuries. In addition, the emplacement tunnel collapsed to a greater extent than expected, causing damage to experimental equipment. No radiation release occurred, and there was no personnel radiation exposure.

Consequences: 1 fatality, 14 injuries.


© 2006 by Wm. Robert Johnston.
Last modified 6 November 2006.
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