On Hawaii’s Big Island a hiker stumbled upon two unexploded bombs in the lava fields of Mauna Loa. This is the largest volcano on Earth. These bombs were part of the twenty bombs dropped on 27 December 1935 as an effort to divert lava. The lava flow did slow the next day. But scientists at the time and today believe it was a coincidence.
The idea of using bombs to prevent volcanoes came up in 1881. This was to prevent the threat to Hilo due to Mauna Loa eruption. When it started to erupt in 1933 the idea resurfaced. A month after the 1935 eruption the lava pond at the Mauna Kea started to flow toward Hilo. The lava threatened to spill into the Wailuku River, which could cut off Hilo’s water supply. The army planes were used to drop explosive bombs quickly and accurately.
The founder of Hawaiian Volcano Observatory (HVO)Thomas A. Jaggar, Jr said in a radio broadcast at the time “Our purpose was not to stop the lava flow, but to start it all over again at the source so that it will take a new course.”
The eruption ended six days after the bombs were dropped and Hilo was not destroyed by the lava. The strategy was tried in 1935 and 1942.