Instability of the volcanic slope on La Palma’s western flank

Instability of the volcanic slope on La Palma’s western flank is presented as a geological hazard poised to turn local change into a transatlantic catastrophe. The western flank is already described as destabilised, and an underwater landslide worked by worms could help detach it from the island. The possibility is not treated as a confirmed future event: its timing cannot be fixed, and the projections depend on uncertain processes. But in the novel’s chain of ecological and geological crises, uncertainty about when the slope might fail does not make its consequences remote or containable.

Geological condition and warning

The warning begins with the 1949 eruption of Cumbre Vieja, which opened a fault running for kilometres along La Palma’s western flank. During that eruption, a section of the ridge slipped four metres into the ocean. Stanley Frost, who says he has monitored the area for several years, argues that the fault may indicate fissuring within the island’s rock. He identifies an unusually large quantity of groundwater trapped in the flank as an additional vulnerability: a future influx of hot magma could cause the water to expand and evaporate rapidly, raising pressure within the rock.

In Frost’s assessment, the eastern and southern flanks are pressing against the western one, while the western slope is already unstable. If it broke away, about 500 cubic kilometres of rock could enter the ocean. The evidence supports a serious warning, not a dated forecast. Frost presents the question as when a collapse might occur, rather than whether it is possible, but acknowledges that the interval could be a century or a thousand years and that the volcanoes provide little warning. The scale of the proposed outcome is starkly out of proportion to the apparent quiet of the island.

Two possible triggers

The account identifies two routes to failure. One is volcanic: a new eruption could send hot magma into the vent, rapidly vaporising groundwater and supplying the pressure that might blast the western flank into the sea. The other is submarine. An underwater avalanche could undermine the volcano’s flank; the resulting movement might cause a minor earthquake and destabilise Cumbre Vieja, perhaps even triggering an eruption. Frost argues that either route could end in detachment, though neither the precise sequence nor its timing can be known with certainty.

This second route connects the La Palma danger to the crisis on the Norwegian continental slope. There, worms and bacteria have altered methane hydrates, while ice and gas destabilisation feed into seabed collapse. Yvonne Mirbach describes the broader mechanism as non-linear: melting ice allows gas to escape, the gas cracks more hydrates, and the seabed begins to fail, with developments potentially accelerating toward a crisis point. At La Palma, Frost characterises the worms’ work as a smaller version of the process behind the European disaster, but one potentially powerful enough to detach part of the volcano. The novel therefore places the flank within a wider pattern of biological activity intensifying geological weakness, without making the La Palma collapse itself an accomplished fact.

From flank failure to Atlantic wave

Gerhard Bohrmann explains how a collapse could displace water on an immense scale. The falling rock would form a dome at the ocean surface; the estimated impact speed is 350 kilometres per hour. Debris might extend 60 kilometres across the seabed, preventing water from flowing back over the landslide and creating an air cavity that would displace still more water. Bohrmann notes that the precise result is disputed, but his scenarios all involve a mega-wave. Its probable height near La Palma is estimated at 600 to 900 metres, and it could travel across the Atlantic at 1,000 kilometres per hour. As the wave moved farther from its source, it would flatten and lose energy, but distance would not make it harmless.

The projected sequence gives the threat its geographical reach. The Canary Islands could be overwhelmed almost immediately. About an hour later, a wave around 100 metres high could strike the northwest African coast. Six to eight hours after the eruption, a wave around 50 metres high could reach the Caribbean and flood the eastern American coast from New York City to Miami; Brazil could face a wave of comparable force soon afterwards. Smaller waves could reach Spain, Portugal and the British Isles, while the effects on the wider European economy could be severe. Bohrmann stresses that a wave far shorter than the initial mega-wave could still flatten New York City: its force would act at the base of buildings, not be defeated by their height.

A disaster measured against the North Sea

The previous landslide in the Norwegian continental slope makes the warning more than an abstract exercise in scale. There, hydrate deposits transformed by worms and bacteria became porous and brittle before disintegrating across 150 kilometres of slope. The released gas rose through the seabed; enormous sections of rock collapsed, setting off successive slides. In the resulting North Sea tsunami, oil infrastructure in northern Europe ceased to function, coastal towns were ravaged or destroyed, and hundreds of thousands of people died. The episode demonstrates how a process that begins beneath the seabed can spread through geological layers and then become a disaster for distant coastlines and human settlements.

The La Palma projection is nevertheless distinct from that earlier event. The North Sea tsunami has already occurred in the narrative; the western-flank collapse remains a prospective danger. Frost compares the potential La Palma wave with the European tsunami, noting that waves in the Norwegian fjords had reached 40 metres, but he uses that comparison to indicate the possible scale of the Atlantic consequences, not to claim that the two disasters would unfold identically. The contrast between an observed chain reaction in northern Europe and an uncertain but potentially larger volcanic collapse sharpens the novel’s central tension between limited prediction and enormous exposure.

Uncertainty, response, and significance

The danger is difficult to manage because the relevant processes are hard to observe and their timing cannot be confidently stated. On the Norwegian slope, researchers warned that the hydrates were destabilising, yet the crisis developed through chaotic and potentially exponential changes. In the La Palma discussion, Stanley Frost likewise argues that worms have begun work in places that are difficult for people to reach and that the process could move faster than it did off Norway. Jan van Maarten mentions an operational prototype suction pipe that works at depths of up to 300 metres, but the discussion does not establish that it could reach or halt the threatening activity.

The authorities on La Palma describe the theory as dubious. Frost interprets their failure to address the issue in public statements as an effort to avoid alarming tourists, and he points to earlier volcanic collapses and monitoring of Kilauea as evidence that flank movement deserves attention. His examples include waves generated by eruptions or collapses at Oshima-Oshima in 1741 and Ritter Island in 1888, as well as the continuing seaward movement of Kilauea’s southeastern flank. These comparisons do not determine what La Palma will do; they frame collapse as a recognised geological possibility rather than an unprecedented fantasy.

The western flank’s instability thus brings together competing timescales: volcanic change that may take centuries, submarine damage that could accelerate over weeks, and a tsunami that could cross an ocean within hours. Its significance lies in this compression of uncertainty and consequence. The threat is still hypothetical, but the North Sea disaster has already shown how a hidden process can become a public catastrophe before institutions can establish exactly what is happening. La Palma’s apparently tranquil setting therefore sits beside a projected chain of failures whose scale would exceed the island, the surrounding ocean and the ordinary limits of local disaster planning.