Humans have tried many ways to stop lava in the past, from attempting to freeze it in place by cooling it with sea water, to using explosives to disrupt its supply, to building earthen barriers.
It’s too soon to say if Iceland’s earthworks will succeed in saving Grindavík, a town of about 3,500 residents, and a nearby geothermal power plant. As a volcanologist, I follow these methods. The most successful attempts to stop or reroute lava have involved diversions like Iceland’s.
FREEZING LAVA IN ITS TRACKS
In 1973, Icelanders attempted the most famous “lava freezing” experiment. They used water hoses from a flotilla of small boats and fishing vessels to protect the small island community of Heimaey from the Eldfell volcano’s lava.
The lava flows were threatening to close off the harbor, which is critical to the region’s fishing industry and a lifeline to the Icelandic mainland. The eruption ended before the success of the strategy could be properly evaluated, but the harbor survived.
FIGHTING LAVE WITH EXPLOSIVES
Hawaiians used explosives dropped from planes in 1935 and 1942 to try to disrupt lava flows from Mauna Loa volcano that were threatening the town of Hilo on the Big Island.
The idea was to disrupt the channels or lava tubes in the volcano that were supplying lava to the surface. Neither attempt was successful. The explosions created new channels, but the newly formed lava flows soon rejoined the original lava channel.
LAVA BARRIERS AND DIVERSIONS
Most recent efforts have focused instead on a third strategy: building dams or ditches in an attempt to divert the lava’s flow toward a different path of steepest descent, into a different “lavashed,” a concept similar to a watershed but where lava would naturally flow.
Results have been mixed, but diversion can be successful if the lava flow can be clearly diverted into a distinct area where lava would naturally flow – without threatening a different community in the process.
