Thread by @SquigglyVolcano

In 1935, the US military dropped 3.6 tons of explosives on Mauna Loa, the largest volcano on Earth. And in 1992, engineers blew a hole in Mount Etna with 7.7 tons of dynamite.

Their aim: to divert the flow of deadly lava.

Did it work?

Me, for @NatGeo nationalgeographic.com/science/articl…

First off, this came about thanks to a little side note in my upcoming book, SUPER VOLCANOES—which, by the way, has got some lovely reviews and is out in the US next week! Preorders mean a lot, so if you fancy a copy, click here: amazon.com/Super-Volcanoe…

I've told the abridged version of the Hawaiian tale before, but it was fun to expand on it and dive into other attempts to divert lava flows with explosives.

Turns out that lava very often doesn't care how much you try to blow it up. It'll just keep on flowing.

Diverting lava is incredibly difficult. It makes its own topography and applies a bulldozing-like force and scorching heat to its surroundings. It acts the part of a feral hadean beast, changing direction and speed on a whim. So what can you do to divert it?

Most of the time, when you have eruptions involving lava that threaten lives and livelihoods, the lava has already erupted so close to people that diversion attempts are already too late—and you certainly can't use explosives at that point.

Sometimes, when the lava flow is advancing on a town or city but it's still fairly far away, diversionary attempts can be made. Earthen barriers can slow its advance, and if you're by the sea, spraying it with a ton of cool water can also achieve the same effect.

But all of this only buys time. If the volcano decides to keep erupting, ultimately, the volcano will win.

Back in 1881, though, explosives were considered for the first time. Could they be used to somehow redirect the flow of lava?

Facing down a relentless lava flow, the villagers of Hilo in Hawaii wondered what to do. Princess Ruth Keʻelikōlani arrived at the scene to pray to the volcano goddess Pele and provide material offerings, including brandy and scarfs.

The lava flow did stop shortly afterwards...

...but had it not been stanched by the princess’s pleas, local authorities were prepared to set off an explosion at the front of the lava stream with a hefty supply of gunpowder. T'was never used though.

Everything changed in 1935, when Mauna Loa erupted again, threatening Hilo.

Thomas Jaggar, the founder and director of the Hawaiian Volcano Observatory, wondered if explosives could be used to divert the flow of lava.

The lava was being funneled to Hilo in tubes of its own making, which kept it hot and fluid longer than it ever would be on the surface.

So why not blow holes in the sides of these tubes? You could cause a collapse and block them up, or open up a wound from which that threatening lava could be exsanguinated.

So on December 27, 1935, the US military sent bombers over Mauna Loa and dropped 20 TNT bombs on it.

It didn't work. The lava flow did stop soon after, but that's only really because Mauna Loa stopped erupting. Another attempt in 1942 also failed.

Volcanoes 2, Explosives 0.

According to The Last Volcano by John Dvorak, Colonel Delos Emmons, who oversaw the 1935 operation, flew over the lava flows with Jaggar on an initial reconnaissance flight.

He was...a nervous person.

Frightened by both the ferocity of the inferno below, and concerned about tales of the goddess Pele taking revenge on anyone trying to alter the eruption, he brought a pig with him on a subsequent overflight.

This porcine was, sadly, not so much a companion but an offering—one that was promptly tossed out of the plane and into the molten matter below. Oof.

Nearly half a century later, and half the world away, Italy's Mount Etna erupted. The 1983 eruption was fairly destructive, and public pressure convinced the authorities to try and use explosives to divert the flow of lava.

In order to permit this, a law had to be repealed because of some...awkwardness a few centuries earlier. An Etnean eruption in 1669 threatened the village of Catania. They diverted it with barriers...into the nearby village of Paterno, who promptly diverted it back to Catania.

Lava diversion was outlawed ever since, but said law was repealed in 1983 when Etna's lava began looming over several towns on its slopes.

This time, explosives were planted on foot—not easy, seeing as the heat of the lava threatened to blow them up prematurely.

A hole in the side of a major lava artery was made, but it quickly sealed itself up and the experiment was considered to be a failure.

Volcanoes 3, Explosives 0.

Between 1991 and 1993, Etna erupted like it was going out of fashion. Lava was about to hit a town of 10,000 people, so something had to be done.

Earthen barriers were quickly eaten up. US military helicopters dropped concrete blocks into an opening in a lava tube to try and cut off the main supply of lava to the dangerous flow...but the lava ate those up too.

Screw it, scientists thought: explosives get another shot. They dug out some artificial trenches, stuck 7.7 tons of dynamite into a hole beneath a lava tube, and pulled the trigger.

Boom: most of the lava bled out of the new chasm, and the lava flow threatening the town stopped just short of it. Etna's eruption calmed down soon after, but this time the explosives really did divert the flow of lava and save a town.

Volcanoes 4, Explosives 1

So explosives can work—but only in very specific scenarios. And remember, if the volcano wants to keep erupting, you're only buying time in a battle you'll end up losing. We're always at the mercy of these magnificent magmatic monsters, those makers and breakers of worlds.

End!

Two more things: it seems some Spanish officials are suggesting using bombs to divert the flow of lava on La Palma. I actually asked experts about this and the main problem would be: divert to where? You're always going to hit someone's house...

https://twitter.com/Cahora/status/1453114975925514244?s=20

The other thing was a really curious side note about the 1992 Etna bombing campaign. You would think that such a dramatic operation, which happened in late-May, would be ingrained in the minds of those living on Etna’s flanks. But no. Why?

Well...

That same month, on May 23, another blast had captured everyone’s attention: 13 barrels of TNT and Semtex exploded beneath a Sicilian motorway—a successful plot by the Sicilian Mafia to kill the prosecuting magistrate Giovanni Falcone.

That's the blast most remember...

Anyway: thanks to @etnaboris, @dramydonovan, @AriannaSoldati, Tobi Dürig, @stavrosmel, @swrtsang and Hannah Dietterich for talking to me for this fun piece, and to @vmjaggard99 who always lets me write stories of an explosive nature.