The earthquake bomb designed to collapse buildings from beneath

Countries & Cities · Published 15 October 2026 Swipe more like this →

In short: Conventional bombs often fail against heavy fortifications because they dissipate energy through the air. British engineer Barnes Wallis solved this by designing a weapon that traveled deep underground first. By exploding beneath a target, it used the earth itself to transmit a devastating shockwave into the foundations.

Developed by aeronautical engineer Barnes Wallis during World War II, the Tallboy was a 12,000 lb (5.4 t) 'earthquake bomb.' Unlike standard 'blockbuster' bombs of the era, which had thin skins to maximize explosive weight, the Tallboy featured a casing cast in one piece of high-tensile steel. This allowed it to penetrate deep into the ground or fortified structures without breaking apart before detonation.

The weapon relied on precision physics: it was designed with an aerodynamically clean shape and a twisted tail fin system to create a gyroscopic spin during its fall. Dropped from 18,000 ft at 170 mph, it would hit the ground at roughly 750 mph. This high terminal velocity enabled it to bore through up to 16 ft of concrete or penetrate hillsides entirely. For underground targets, it used three inertial 'Tail Pistols' with delays of up to 30 minutes, ensuring the bomb exploded only after reaching its intended depth.

The strategic goal was a 'camouflet'—a cavern or crater that would cause a structure to collapse into itself. This was more effective than a direct hit because it shook the entire target, making repairs uneconomic. Notable successes included destroying the V-2 assembly bunker at La Coupole and sinking the battleship Tirpitz. Because they were costly and hand-made using Torpex explosives and TNT, Tallboys were reserved for high-value strategic targets like U-boat pens and railway tunnels.

The weapon's immense weight required significant modifications to the Avro Lancaster bomber, including removing armor plating and defensive armament to maintain flight capabilities. Despite its success, the technology was so specialized that it remained a niche tool of the RAF’s 617 Squadron, used primarily when conventional bombing proved ineffective against hardened Axis defenses.

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