La Palma deep-sea worm removal and slope collapse

The La Palma deep-sea worm removal and slope collapse is the turning point in an ambitious effort to clear an infested volcanic terrace: a powerful suction system removes worms in great numbers, but extended work on the slope helps set off a landslide. The operation exposes the limits of treating the visible infestation as the whole problem. Beneath the worms lie bacterial mats and methane hydrate, while the equipment intended to make the seabed safer can itself disturb the unstable ground.

Background and Objective

The operation grew from evidence that worms were spreading across vulnerable submarine volcanic slopes. A robot sent to Hawaii had found the southeastern flank swarming with them, and Frost expected La Palma to be manageable by comparison with a continental slope. Bohrmann questioned whether one suction tube could ever clear a much larger area, such as the American continental slope. The disagreement established both the scale of the threat and the limits of the proposed remedy: the team was attempting to remove a biological infestation whose reach might exceed its equipment.

The work took place aboard the Heerema, where a large suction tube and a separate lighting-and-camera system were lowered by cranes. Frost’s team included technicians from De Beers, among them Jan van Maarten, who had helped deliver the technology. Frost framed the effort as a campaign to cleanse the planet of the worms; Bohrmann’s concern was more immediate and conditional. Even if they removed the worms, he could not know how many bacteria had already entered the ice, or whether it was already too late to prevent the collapse of Cumbre Vieja.

The Deep-Sea System at Work

The lighting unit began as a ten-metre package of pipes and struts suspended above the waves. After descent, it unfolded into a lattice-like scaffold, approximately half the size of a football pitch, with lights and cameras connected to the Heerema by fibre-optic cable. Propellers moved the framework through the water. At roughly four hundred metres down, its illumination revealed the volcanic terrain in small sections, allowing the operators to approach the ridge cautiously rather than working blind.

The first close view brought the scale of the infestation into focus. A sonar image disclosed a terrace-like protrusion and then a ridge covered with writhing worms. Bohrmann recognized the sight as the nightmare he had associated with the collapse of the Norwegian slope. The illuminated area was only forty metres of terrain; if the rest of the flank looked the same, the team’s task was far larger than that glimpse could contain.

The suction device was a pump that created a vacuum, drawing in anything that passed before its mouth. When the team switched it on, nothing happened at first. The worms continued undisturbed, and the control room fell quiet as Bohrmann watched the monitors, wondering whether the tube was too long or the pump too weak. Then the picture changed: the worms tore loose, rose vertically, and rushed toward the cameras before disappearing into the tube. The apparent failure abruptly became a powerful extraction system.

A Success with an Unseen Cost

The tube crossed the terrace in a zigzag, vacuuming worms as it went. Sediment billowed so heavily that the rock vanished from view, and the team had to wait for the water to clear before judging the result. Over the next sixteen hours, the equipment continued operating, sucking up pink worms by the tonne. Many burst during transit; others arrived writhing in their death throes. They were caught in large nets beneath the tube, and slides carried the accumulated bodies into a freighter moored alongside the Heerema. Frost returned to the control room with worm corpses in his hands, and even Bohrmann joined the team’s applause.

When the sediment settled, however, the cleared view revealed more than bare volcanic rock. The lava appeared marbled, and isolated strings of bubbles rose from its surface. Bohrmann identified the pattern as bacterial mats. He could not tell how far the bacteria had penetrated the sediment: if they had colonized only the surface, there might be no danger, but the grey lines on the screen were methane hydrate. Removing the visible worms therefore did not resolve the uncertainty beneath them.

For a time the work seemed to offer a narrow path toward stabilization. Readings from the Polarstern expedition suggested the infestation was confined to the terrace. The methane level was above average, but Bohrmann thought that if the worms and bacteria could be removed, partially eroded hydrates might restabilize. The team had already been operating for hours, with shifts relieved repeatedly, and the tube and lighting scaffold continued northward. That hope depended on the assumption that the operation could continue without damaging the ground it was meant to protect.

The Landslide

Bohrmann noticed a flash on the monitors and ordered the tube moved. The operator reported that large chunks were being sucked up and that the tube was becoming unstable. At first Bohrmann thought of the Sonne and feared another blowout. He then recognized a worse possibility: they had stayed too long over the same section, the plateau had come loose, and the vacuum was tearing at the sediment. The billowing cloud expanded; pressure shook the scaffold, and the operator identified the event as a landslide.

Bohrmann ordered the pump stopped and the equipment moved away from the terrace. Through the sediment and debris, lava boulders crashed down from above. The concern was no longer confined to the machinery: cracks spreading through the nearly vertical flank could release larger boulders, turning a small slide into an avalanche and reviving the disaster scenario the operation was intended to avert. Bohrmann imagined a towering dome of water, but the immediate danger remained uncertain; the team could not see how much debris had fallen through the cloud.

The pump was off, but the tube appeared buried beneath rubble. Its control system still processed commands yet could not move the equipment. Bohrmann instructed the crew not to try to free it, since further intervention might cause more damage. They waited three hours for the cloud to settle. When the tube’s mouth finally became faintly visible, Bohrmann judged that they had escaped with a bruising. The excerpt establishes serious disruption and a landslide, but does not establish that the Heerema or its crew were lost.

Significance and Limits

The operation’s reversal is built into its method. The suction system is effective precisely because it pulls material from the seabed; on a vulnerable terrace, that same force can disturb sediment and contribute to slope failure. The campaign first makes the worms look removable, then exposes the bacteria and hydrate beneath them, and finally shows that the act of removal can become part of the danger. The team’s machinery is not a neutral instrument outside the ecological crisis: its reach, duration, and interaction with the terrain help determine what happens.

The contrast between Frost’s language of cleansing and Bohrmann’s growing caution sharpens the event’s significance. The team can count the worms drawn into the tube, but cannot immediately determine how far bacteria have entered the sediment or what the damaged flank will do next. Their early celebration follows a real technical success, yet that success does not amount to ecological control. At La Palma, the visible infestation is only one layer of the crisis, and intervention offers no simple separation between repair and further disturbance.