Written by Louise Rasmussen and Johannes Birkbeck
COPENHAGEN (Reuters) – Icelanders have been working around the clock to build dams the size of three-story buildings to protect a vital power plant and homes from lava flows since volcanoes near the capital Reykjavik that have been dormant for nearly 800 years have become active. .
The six volcanic systems, which experts expect to remain active for up to three centuries, extend under the Reykjanes Peninsula in southwest Iceland, which is inhabited by 30,000 people, nearly 8% of the country's total population.
They form an underground network on the peninsula, extending to the outskirts of the capital, which has witnessed five eruptions since 2021.
Amid fears about an imminent eruption, authorities in November began building defensive walls around the Svartsinji geothermal power plant on the peninsula.
Since then, nearly 100 bulldozers, excavators and transport trucks have been working non-stop around the plant, according to Christine Hardarson, who heads operations at energy company HS Orca, Svartsinge's owner.
In total, about 560,000 cubic meters of gravel and solid volcanic rock – enough to fill 20,000 trucks – will be used to protect the plant.
“They have to divert the lava so that it flows alongside the barriers. If you try to stop it, the lava will build up and eventually go beyond the barriers,” Feder Rennison, Iceland's head of civil protection and emergency management, told Reuters.
Defenses have also begun to be built around the nearby town of Grindavik, home to one of Iceland's main fishing ports and nearly 4,000 residents who were evacuated in December before the latest volcanic eruption north of the city.
The first barrier proved effective in diverting lava away from Grindavik, but when cracks opened on the other side of the barrier, the lava reached the city and set some houses on fire.
The largest barriers are about 40 meters wide, between eight and ten meters high, and four meters wide at the top.
Rennison said it was expected to take six weeks to complete the seven-kilometre half-circle around Grindavik.
It will take almost twice the amount of material required in Svartsingi, according to Ari Gudmundsson, a civil engineer at the Verkes engineering company working on the barriers.
Similar dikes or dikes have been attempted in Italy, Hawaii and Iceland to protect against lava but on a smaller scale, according to Gudmundsson.
When Mount Etna, an active volcano in Italy, erupted in late 1991, a barrier measuring 234 meters long and 21 meters high was created. The lava was trapped for about a month before it eventually flowed over the structure.
Icelanders first attempted to build defensive walls on the island of Heimaey when a 1973 volcanic eruption swept through the town of Vestmannaeyjar, forcing the evacuation of all its residents.
Several volcanic eruptions have struck Iceland since then, but usually far from cities and vital infrastructure. When volcanic activity began on the Reykjanes Peninsula in 2021, new attempts were made to build a defence.
“We made some barriers, short ones, to gain experience and try to direct the lava flow away from one area that might eventually lead to Grindavik,” Gudmundsson said.
Engineers try to adjust the height and slope of the barriers.
“The main thing we've seen is that the barriers work, and now we know more about how to build them and how to use them,” Rennison said.
The Civil Protection Department is also digging hot water pipelines deeper underground and raising power and communications lines higher to protect them.
Attempts are also being made to insulate onshore pipelines and power cables from the hot lava.
Icelanders have a mysterious relationship with volcanoes, according to Sigurdur Inge Johansson, Iceland's infrastructure minister.
He told Reuters: We have to remember that our green geothermal energy, amazing tourist attractions and luxury in Iceland come from the power of volcanoes.
“Sometimes it's good and benefits people, but sometimes it threatens us.”
(Reporting by Louise Brosch Rasmussen and Johannes Gottfredsen Birkbeck; Editing by Jacob Gronholt Pedersen and Alexandra Hudson)
