Over the years, researchers have identified signs that the seabed around the Titanic wreck has been hit by huge underwater landslides in the distant past. Huge volumes of sediment appear to have cascaded down the continental slope from Newfoundland to create what scientists call an "instability corridor". They estimate the last one of these "destructive" events occurred tens of thousands of years ago, creating layers of sediment up to 100m (328ft) thick. But they also happen extremely rarely, says David Piper, a marine geology research scientist with the Geological Survey of Canada, who has spent many years studying the seabed around the Titanic. He compares such events to the eruption of Mount Vesuvius or Mount Fuji in terms of how often they might occur – on the order of once every tens of thousands to hundreds of thousands of years.

Other events known as turbidity currents – which are where water becomes loaded with sediment and flow down the continental slope – are more common and may be triggered by storms. "We show a repeat interval of perhaps 500 years," says Piper. But the topography of the seafloor in the area would likely steer any flows of sediment down a feature known as "Titanic Valley", meaning it would not reach the wreck at all.

Both Seiffert and Piper say it is unlikely that such an event might have played a role in the disappearance of the Titan submersible.

There are other geological features around the wreck site that have also still to be explored. In a previous expedition to Titanic with OceanGate, Paul-Henry Nargeolet – a former French Navy diver and submersible pilot – visited a mysterious blip he picked up on sonar in 1996. It turned out to be a rocky reef, covered in sealife. He had hoped to visit another blip he had detected near the Titanic wreck in the latest expeditions.

While the search for the missing craft continues, there are few clues about what may have happened to the Titan and its crew. But in such a challenging and inhospitable environment, the risks of visiting the wreck of the Titanic are as relevant today as they were in 1986 when the first people to set eyes on the vessel since it sank made the journey to the depths.

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