1935 Lava Bombing Mission: US drops 40 bombs on Mauna Loa flow; effectiveness unresolved

On December 27, 1935, something unusual happened in the skies above Hawaiʻi. US military aircraft dropped 40 bombs, not on an enemy, but on a river of molten lava pouring down the slopes of Mauna Loa. The eruption had begun a month earlier inside the volcano's summit caldera, and by late December, a fast-moving lava flow was heading straight for Hilo and the water supply that fed it. Officials were desperate. Scientists believed that explosives could break apart the underground channels carrying lava toward the town, forcing it to spread out and slow down. What followed became one of the earliest recorded attempts at lava flow diversion, and a story still argued over nearly a century later.The Eruption That Threatened Hilo's Water SupplyThe Mauna Loa eruption started on November 21, 1935, inside the volcano's summit caldera. Within days, activity shifted down the Northeast Rift Zone, and a new vent opened on the volcano's northern flank on November 27. From this vent, smooth pāhoehoe lava began collecting in the saddle area between Mauna Loa and Mauna Kea before turning east toward Hilo. According to the US Geological Survey, the flow was advancing at roughly one mile a day, which ...