Worm removal off La Palma triggers a submarine landslide during an attempt to vacuum a dense infestation from the flank of Cumbre Vieja. The operation is meant to remove worms and associated bacteria so that partly eroded methane hydrates might restabilise; instead, suction and disturbed sediment help loosen the terrace and set a slide in motion. The episode turns a technological intervention into the very danger it was designed to prevent, with the possibility of a much larger collapse hanging over the crew.

The removal plan

The urgency of the operation is shaped by earlier evidence of the worms’ reach. Stanley Frost reports that a robot sent to the south-eastern flank of La Palma found it swarming with worms, while attacks were also being reported against other volcanic islands. Frost presents the new equipment as a way to clear the infestation on a scale beyond ordinary sampling. Gerhard Bohrmann, however, distinguishes the relatively manageable La Palma site from the much larger American continental slope: a single suction tube cannot clear that seabed. The mission is a local intervention, not a solution to the global threat.

The technology has been assembled with striking speed. Frost’s team and technicians from De Beers, including Jan van Maarten, gather in the control room to operate what is described as the first deep-sea vacuum cleaner for worms. Its purpose is specific: remove the organisms from the seabed, and, Bohrmann hopes, the bacteria as well. Earlier work had relied on remotely operated vehicles to inspect the deep and retrieve samples. A Victor 6000 could operate to six thousand metres, remain submerged for days, and send data up a cable to a control room aboard ship; the planned reconnaissance was to last forty-eight hours. That exploratory apparatus gives way here to machinery designed not merely to observe the worms but to extract them.

The infestation and the machinery

The team advances a lighting scaffold, propelled by two swivelling propellers, towards a terrace on the volcanic flank. The rock rises from the darkness as a jagged wall of lava. On the sonar, the operators first locate the terrace, then a ridge appears unexpectedly close. Its surface is covered with writhing bodies. The sight recalls the collapse of the Norwegian slope to Bohrmann: the forty metres illuminated by the floodlights are enough to make him fear that the entire flank may be similarly infested.

The removal system is far larger than a sampling tool. At full extension, its segmented, rubber-insulated tube reaches half a kilometre into the depths and measures three metres across. Floodlights, cameras and swivelling propellers surround its mouth; from the Heerema, operators can steer it in multiple directions. The control-room display combines the scaffold’s images with footage from the tube, giving the operators a view of both the machine and its target. But the operation still depends on delicate coordination: the joysticks require sensitive handling, and a co-pilot must watch for what the driver might miss.

Once the tube reaches the terrace, the suction works. Worms are drawn up in such numbers that the picture fades to a flicker, while sediment swirls into the illuminated water. The crew considers clearing the floodlit zone in a zigzag pattern, then shifting the lights and tube to the next section. The apparent success is also a warning in retrospect: the machine is removing organisms and sediment from a vulnerable volcanic surface, not operating on stable, inert ground.

From extraction to landslide

Bohrmann remains at the screens as the scaffold and tube work gradually northward. He understands that the terrace will take at least another couple of days to clear, but the readings from the Polarstern expedition suggest the infestation may be confined to this area. Methane levels are above average, yet he sees no immediate cause for alarm. If the worms and bacteria can be removed, he reasons, partly eroded hydrates may have a chance to restabilise.

That guarded optimism breaks when he notices a glittering flash in the water and asks for the tube to be moved. The operator reports that large chunks of something are being sucked up and that the tube is becoming unstable. Bohrmann recognises the danger as resembling the Sonne blowout, and initially fears another eruption. But this is worse in a different way: the vacuum is tearing at sediment on a loosened plateau, after the crew has remained too long over the same section of terrace.

A billowing cloud of sediment swells and then appears to explode. A pressure wave rocks the lighting scaffold, and the picture judders. The operator identifies a landslide; Bohrmann orders the pump stopped and the equipment moved away from the terrace. By then, lava boulders are already crashing down onto it. Switching off the pump does not stop the slope. Debris continues to fall, and the crew watches for cracks to spread through the nearly vertical flank.

Consequences and significance

The danger lies in the geology of the flank as much as in the machinery. Lava is porous, and Bohrmann fears that what begins as a small slide could become an avalanche as larger boulders detach. The feared chain of consequences is not simply damage to the equipment: a larger collapse could produce the catastrophic scenario the worm-removal project was meant to avert. His thought of a dome of water rising six hundred metres makes the scale of the possible disaster explicit, while his recognition that there may be no time to escape marks the crew’s shift from operators to potential victims.

An attempted rescue underscores the limits of remote technology. Rambo, a smaller ROV with four cameras, side and stern thrusters, and two articulated arms, descends towards the terrace on an electro-optical tether. Its cameras and propellers remain intact, but the suction tube is jammed. Rambo can move rocks one by one, yet a sharp splinter of lava has pinned the tube against a ledge. Bohrmann concludes that the task requires momentum the robot cannot generate. The tools that had made the operation possible can inspect the trapped equipment and shift debris, but they cannot simply undo the conditions that have trapped it.

The episode connects a biological emergency to a physical one. The worms are treated as an infestation that can be cleared, and the powerful tube initially seems to validate that approach; the landslide reveals that removal itself can disturb the terrain on which the intervention depends. The operation’s reversal is therefore more than a failed piece of engineering. It makes the volcanic slope an active participant in the crisis, while showing how an attempt to control one part of a connected deep-sea system may intensify another.