Minor Scale
1985 CE.
Shown on the map at 33.620°, -106.475°.
Minor Scale was a test conducted on June 27, 1985, by the United States Defense Nuclear Agency (now part of the Defense Threat Reduction Agency) involving the detonation of several thousand tons of conventional explosives to simulate the explosion of a small nuclear bomb.
Text from the Wikipedia article Minor Scale, licensed CC BY-SA 4.0.