Scientist explains Mount Doom’s eruption on The Rings of Power

The latest episode of The Lord of the Rings: The Rings of Power featured a plot twist of volcanic proportions: after a pitched battle in the Southlands, one of the corrupted elf Adar’s followers used a sword which doubled as a key to open a dam, triggering a natural calamity. The ensuing torrent washed down into the tunnels dug by the orcs, where it eventually found its way under a mountain which should be familiar to any Lord of the Rings fan: Mount Doom, the very volcano that Sauron will one day use to craft the One Ring.

When the water hit the magma beneath the volcano, it caused an eruption which covered the Southlands in fire and ash, paving the way for its transformation into the blackened land of Mordor.

In a show filled with magic, it would have been easy to fall back on some mystical reason for Mount Doom’s eruption. Instead, The Rings of Power opted to use a surprising amount of science to pull off this big twist. It was something discussed at length in the show’s writers room, and according to showrunner Patrick McKay, the idea to use more realistic means to detonate Mount Doom was made to keep things more in line with the overall themes of Tolkien’s work.

“A huge theme in Tolkien is the environmentalism and the way machines and industrializations destroys the land,” McKay says. “We wanted that to be central and core all the time. It’s a thing that comes up again and again throughout the show. So in the writers room, we asked: What if Mordor was beautiful? All bucolic like Switzerland. And then what could happen that could transform it? We talked about the poisoning of the land — which starts in the first episode with the cow. Then you find out about the tunnels being dug and sulfur is going up into the air. It all builds toward this geologically realistic way of igniting the mountain, which now blacks out the sky for a very practical reason — Adar, our villain, sees the Orcs as his people and they deserve a home where the sun doesn’t torment them. We’re hoping it will take people by surprise.”

The science of Mount Doom’s eruption, explained

If The Rings of Power left you wondering if a river falling onto magma could actually trigger a volcanic eruption, or how exactly it all works, you aren’t alone. The Hollywood Reporter’s James Hibberd got in touch with Jeffrey Karson, professor of Earth and Environmental Sciences at Syracuse University, to get into the nitty gritty of how volcanic eruptions work. Karson is a specialist in volcanic activity and has published writings about the role of water in eruptions, so while he may not have gone down to Mordor himself to see what the orcs were up to, he certainly knows quite a bit about the topic.

“Violent volcanic eruptions occur in large part because water is involved,” Karson explained. “The water is dissolved in the magma. The magma rises to the surfaces, the water makes bubbles that can turn to steam and the steam and water expand so rapidly that they basically blow the magma apart. That stuff piles up near a central vent and that’s what makes big volcanos.”

The way that an eruption could turn extra violent is if the steam created by the water and magma mixing has no exit. However, Karson does note that this is likely to cause a “steam eruption,” so The Rings of Power may have exaggerated things a tiny bit by having Mount Doom transform the landscape so drastically.

“If that water is in a confined area, like a bottleneck, there’s going to be a steam eruption — we call it a phreatomagmatic eruption. We see that happening in Hawaii all the time where lava flows into the ocean, and some of the lava can get blown around if the water gets trapped under it.”

Amusingly, Hibberd wasn’t able to share with Karson exactly why he was asking these questions about a volcano, and the scientist was a bit curious how anyone could actually dig the two kilometers below the Earth’s surface to be able to reach the subterranean chambers where the magma is created. Hibberd notes he was unable to disclose that “Orcs are super-industrious creatures known to be particularly skilled at extensive digging projects,” but obviously they had no problem getting the job done.

As for next week’s episode, this is the first time that such a huge shift has happened on The Lord of the Rings: The Rings of Power. It will be interesting to see how the show moves forward. Patrick McKay teased what awaits in the season’s penultimate episode:

"We think that Charlotte Brandstrom, the director, and Alex Disenhof,  the cinematographer, did an incredible job with the seventh episode. You’ll see who survives [the Mount Doom eruption] and there are some unlikely pairing of characters. The episode is about consequences and Galadriel is facing the consequences of her judgment."

We’ll see the fallout from Mount Doom’s eruption when The Rings of Power airs its next episode on Friday, October 7 on Prime Video.

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