That Time We Bombed a Volcano

Who says you can’t fight mother nature? 

Pilots are advised to avoid volcanic eruptions, but in 1935, a squad of U.S. bombers took a more aggressive approach. 

A crisis erupted (literally) on November 21, when lava spewed from a fissure on the summit of the nearly 14,000-foot-high Mauna Loa volcano in Hawaii. Six days later, a new vent opened on the volcano’s northern flank. The lava flowed downward, pooling at the base of the massive mountain, where it then began edging its way toward the town of Hilo—at the alarming rate of one mile per day.

Thomas Jaggar, the founder of the Hawaiian Volcano Observatory, grew increasingly worried after he realized the lava could reach the headwaters of the Wailuku River, which supplied water for Hilo’s 15,000 residents.

Jaggar reasoned that explosives detonated near the eruptive vent would divert the flow of lava advancing toward Hilo by collapsing the lava channels—narrow paths of fluid lava with raised rims formed by cooling magma. 

Thus, on December 26, six Keystone B-3A bombers from the 23rd Bombardment Squadron and four LB-6 light bombers from the 72nd Bombardment Squadron were deployed to Hilo from Ford Island’s Luke Field at Pearl Harbor. The next day, Lieutenant Colonel George S. Patton (yes, that Patton) directed the bombers to begin their assault on Mauna Loa. Each carried two 600-pound Mark I demolition bombs, each one loaded with 300 pounds of trinitrotoluene (better known as TNT). Due to the heavy payload, the bombers flew a clearance of just 4,000 feet above the volcano.

A total of 20 of the 600-pound bombs were dropped on the lava channels. Fifteen struck the margins, while five others made direct hits, spraying molten rock in all directions.

Six days later, the eruption ended. Jaggar maintained that the bombers had helped hasten the end of the lava flow. Others are less certain. “Whether the bombing stopped the 1935 lava flow remains unknown, though many geologists today cast doubt,” notes a report later published by the U.S. Geological Survey.

But the rapid response and the bold flying of the American pilots is not in doubt. Today, the 23rd Expeditionary Bomb Squadron flies the Boeing B-52H Stratofortress. How fitting that their squadron patch depicts a cluster of bombs falling onto an erupting volcano.

Mark Strauss is the managing editor at Air & Space Quarterly.