This architect wants to build cities out of lava

Pálmadóttir today lives in Reykjavik, where she runs her own architecture studio, S.AP Arkitektar, and the Icelandic branch of the Danish architecture company Lendager, which specializes in reusing building materials.

The architect believes the lava that flows from a single eruption could yield enough building material to lay the foundations of an entire city. She has been researching this possibility for more than five years as part of a project she calls Lavaforming. Together with her son and colleague Arnar Skarphéðinsson, she has identified three potential techniques: drill straight into magma pockets and extract the lava; channel molten lava into pre-dug trenches that could form a city’s foundations; or 3D-print bricks from molten lava in a technique similar to the way objects can be printed out of molten glass.

Pálmadóttir and Skarphéðinsson first presented the concept during a talk at Reykjavik’s DesignMarch festival in 2022. This year they are producing a speculative film set in 2150, in an imaginary city called Eldborg. Their film, titled Lavaforming, follows the lives of Eldborg’s residents and looks back on how they learned to use molten lava as a building material. It will be presented at the Venice Biennale, a leading architecture festival, in May. 

Buildings and construction materials like concrete and steel currently contribute a staggering 37% of the world’s annual carbon dioxide emissions. Many architects are advocating for the use of natural or preexisting materials, but mixing earth and water into a mold is one thing; tinkering with 2,000 °F lava is another. 

Still, Pálmadóttir is piggybacking on research already being done in Iceland, which has 30 active volcanoes. Since 2021, eruptions have intensified in the Reykjanes Peninsula, which is close to the capital and to tourist hot spots like the Blue Lagoon. In 2024 alone, there were six volcanic eruptions in that area. This frequency has given volcanologists opportunities to study how lava behaves after a volcano erupts. “We try to follow this beast,” says Gro Birkefeldt M. Pedersen, a volcanologist at the Icelandic Meteorological Office (IMO), who has consulted with Pálmadóttir on a few occasions. “There is so much going on, and we’re just trying to catch up and be prepared.”

Pálmadóttir’s concept assumes that many years from now, volcanologists will be able to forecast lava flow accurately enough for cities to plan on using it in building. They will know when and where to dig trenches so that when a volcano erupts, the lava will flow into them and solidify into either walls or foundations.

Today, forecasting lava flows is a complex science that requires remote sensing technology and tremendous amounts of computational power to run simulations on supercomputers. The IMO typically runs two simulations for every new eruption—one based on data from previous eruptions, and another based on additional data acquired shortly after the eruption (from various sources like specially outfitted planes). With every event, the team accumulates more data, which makes the simulations of lava flow more accurate. Pedersen says there is much research yet to be done, but she expects “a lot of advancement” in the next 10 years or so. 

To design the speculative city of Eldborg for their film, Pálmadóttir and Skarphéðinsson used 3D-modeling software similar to what Pedersen uses for her simulations. The city is primarily built on a network of trenches that were filled with lava over the course of several eruptions, while buildings are constructed out of lava bricks. “We’re going to let nature design the buildings that will pop up,” says Pálmadóttir.