Norway: when the mountain will give birth to a tsunami

One day, it's a certainty, part of the mountain will end up collapsing into the water below, causing gigantic waves. Nothing to worry about, however, the inhabitants who live around this fjord in western Norway, serene in the face of the storm. this predicted tsunami.

For decades, the Åkerneset mountain, a mineral behemoth greened by moss and shrubs, has been splitting: its eastern flank is gradually separating, up to 10 cm per year, and sliding irreparably towards the Sunnylvsfjord at its feet.

An aerial photo taken on June 25, 2024 in Stranda, Norway, shows a large crack in the Åkerneset mountain that could cause a major landslide in the future © AFP – Olivier FENIET

“This whole side of the mountain is unstable and moving, which could cause a big landslide,” explains geologist Lars Harald Blikra at the edge of the crack that he has been monitoring for about twenty years on behalf of the Directorate for Water Resources and Energy (NVE).

This collapse “will descend to the fjord and cause the formation of large tsunamis,” he says, an orange helmet firmly fixed on his head. “It could happen in two or three years or in 50 years, we don't know.”

According to a risk assessment report published in 2016 by the Norwegian Civil Security, 54 million m3 of rock could collapse, in one block or in several sections, and generate waves several tens of meters high. high, likely to affect around ten villages on the edge of the fjord system in a few minutes.

Geologist Lars Harald Blikra poses on Åkerneset mountain in Stranda, Norway, with the Geiranger fjord in the background, on June 25, 2024 © AFP – Olivier FENIET

While it inspired the disaster film “Bølgen” (“The Wave”), this scenario is not just fiction. In 1934, a few kilometers away, a landslide triggered a deadly tsunami: 40 people lost their lives in waves reaching up to 64 meters.

“We're not here to have fun,” insists Lars Harald Blikra. “There is a high probability that a major event will occur, posing a serious threat to society.”

– 80-meter waves? –

Olav Arne Merok, a retiree who has spent his entire life in Geiranger, Norway, on his terrace, June 26, 2024 © AFP – Olivier FENIET

Set at the very bottom of the fjord, the villages of Hellesylt and Geiranger are the most exposed. According to the most alarming projections, these tourist hotspots could be submerged by waves of 70 to 80 metres.

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Olav Arne Merok, a septuagenarian who has lived his entire life in Geiranger, would be in the front row.

“Here, we are at about 30-40 meters (above sea level). It's certain that if the wave reaches 90 meters, we will be underwater,” he confides, with a big laugh, from the terrace of his house.

“But you can't live with that idea in your head all the time. Otherwise, you're not living anymore.”

On the quay where the cruise ships, many in the summer, dock, Geir Gjørva, a 69-year-old shipping agent, is also serene.

The wave? “Nobody knows how big it will be, whether it will be like this, like that or even like that,” he says, holding up his hand as a measuring rod. “It can happen slowly (…) or quickly. Nobody knows.”

“It's not a topic in everyday life,” he continues. “Everyone knows that the alert system and the (emergency) measures are very effective.”

Åkerneset, a Norwegian mountain that risks causing a tsunami © AFP – Valentina BRESCHI, Nalini LEPETIT-CHELLA

– “Nightmare scenario” –

Because of the danger it represents, Åkerneset is probably one of the most closely monitored mountains in the world. A whole battery of instruments, GPS and topographic on its surface and probes in its bowels, measure its slightest movements to sound the alarm if necessary.

According to geologists, the rock mass will not suddenly collapse into the fjord. The main subsidence should be preceded by warning signs that will leave enough time to evacuate the populations.

“Having to evacuate thousands of people from a small area because of a risk of landslide is a nightmare scenario for a mayor,” admits Einar Arve Nordang, newly elected mayor of Stranda, the municipality that includes the villages of Hellesylt and Geiranger.

Aerial view showing a ferry sailing in the Geiranger Fjord, Norway, on June 26, 2024 © AFP – Olivier FENIET

But, he assures, “we are ready.”

All the plans are in the box, each authority knows what it will have to do and the population is regularly kept informed of the latest developments.

When the time comes, “we will have multiple ways to communicate,” says Nordang. “We can use a geolocated SMS service, the internet, Facebook, TikTok…”.

On the heights of Åkerneset, experts are looking to push back the deadline. One option would be to drain the mountain of its water, which acts both as a lubricant and a pressurizer, but this solution is complex and expensive, especially since the operations, given the local geography, require the use of a helicopter.

“We think that this would slow down (slope settlement) significantly,” says Sverre Magnus Havig, a senior NVE official. “Instead of this happening in 100 or 200 years, it might happen in the next thousand years.”

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