The US Army Bombed a Hawaiian Lava Flow. It Didn’t Work.

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An anonymous reader quotes the New York Times:
Why were two apparently unexploded bombs sticking out of a lava tube on Hawaii’s Mauna Loa? That’s what Kawika Singson, a photographer, wondered in February when he was hiking on Mauna Loa, the colossal shield volcano that rises 55,700 feet from its base below the sea to its summit. Singson had stumbled upon relics of one of volcanology’s more quixotic disaster response plans. These devices, described in more detail recently in the U.S. Geological Survey Hawaiian Volcano Observatory’s Volcano Watch blog, were two of 40 dropped by the U.S. Army Air Corps in 1935 in an attempt to stop lava from plowing into Hilo, the most populous town on the island of Hawaii. While Hilo was spared as the lava flow naturally lost its forward momentum, it wasn’t the last time that humanity tried to fight volcanic fire with fire of its own. History is filled with schemes to stop molten kinetic rock, and the ineffective 1935 bombing and others show that lava flows are very rarely "a force we humans can reckon with," said Janine Krippner, a volcanologist at the Smithsonian Institution’s Global Volcanism Program… That December, a pond of lava breached its levees and advanced on Hilo at a rate of a mile per day. Fearing it would reach the town and its watershed, Thomas Jaggar, the founder and first director of the U.S. Geological Survey’s Hawaiian Volcano Observatory, called on the Army Air Corps. On Dec. 27, 10 Keystone B-3 and B-4 biplane bombers struck the lava flow, targeting its tubes and channels. Half these bombs were packed with 355 pounds of TNT. The other half were not explosive, and instead designed to emit smoke so the pilots could see where the bona fide bombs landed. Singson found one of those inert devices last month. On Jan. 2, 1936, the lava flows ceased. Jaggar was convinced the bombing worked, but other experts thought it was a coincidence. Pilots did spot several imploded lava tubes, but their collapses were insufficient to block the flow of lava. A similar operation was attempted in 1942, again to not much effect. The conclusion reached by the Times’ reporter? "Dense, superheated lava does whatever it wants."