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Effects of Nuclear Weapons:

Last changed 30 March 2001

The Effects of Underground Explosions

Effects on Structures

The photo sequence below shows a wood-frame house exposed to a nuclear blast at the Nevada Test Site. The test was Upshot-Knothole Annie, a 16 Kt tower shot, on 17 March 1953. The house is 1100 meters from ground zero.

The exposure to thermal radiation was 25 cal/cm^2, about one-quarter of that experienced at ground zero in Hiroshima.

The blast over pressure was 5 psi, and the blast wave created surface winds of 160 mph.

High Speed Photography of a House Being Blasted

House Before Blast House #1: Wood frame test house at NTS (50 K)

House at Detonation House brilliantly illuminated by fireball at the moment of detonation (50 K)

Smoking House 1 sec. after detonation, the thermal pulse has essentially ended

Flash Burned House Flash burned house 1.75 sec after detonation, a split second before blast wave arrival (50 K)

Exploding House 1(50 K)

Exploding House 2(50 K)

House RuinsHouse in ruins (50 K)

This shows the famous "shadow effect" - the discoloration caused by intense flash heating sihouetting undamaged surfaces that were in shadow. "Shadows" can be either dark, like normal shadows, if the heat caused bleaching of the surrounding area (common with pigmented paints); or light, if the surrounding area is darkened (e.g. by charring).

Dark-on-light flash shadow of valve 2.1 km from ground zero in Hiroshima.

Valve flash shadowFlash shadow of valve (68 K)

Light-on-dark flash shadow of bridge railing in Hiroshima.

Railing flash shadowFlash shadow of bridge railing (85 K)