27 December 1935 – “When an eruption of Mauna Loa, a volcano on the Island of Hawaii (ongoing since late November) threatened the town of Hilo on the island’s northeastern coast, a decision was made to try to divert the flow of lava by aerial bombing. (The population of Hilo in 1935 was 15,633.)
The mission was planned by Lieutenant Colonel George S. Patton. The U.S. Army Air Corps’ 23d Bombardment Squadron, 5th Composite Group, based at Luke Field on Ford Island, Oahu, Territory of Hawaii, sent three Keystone B-3A and two Keystone B-6A bombers. The five airplanes dropped twenty 600-pound (272.2 kilogram) Mark I demolition bombs, each containing 355 pounds (161 kilograms) of TNT, with 0.1-second delay fuses.
…U.S. Army planes dropped bombs, targeting the lava channels and tubes just below the vents at 2,600 m (8,600 ft). The object was to divert the flow near its source. The result of the bombing was declared a success by Thomas A. Jaggar, Director of the Hawaiian Volcano Observatory.
Jagger wrote that ‘the violent release of lava, of gas and of hydrostatic pressures at the source robbed the lower flow of its substance, and of its heat.’ The lava stopped flowing on January 2, 1936.”