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Residents of the French border town of Villerupt are dealing with the aftermath of a massive sinkhole that opened near a residential property in early January, raising concerns over ground stability and prompting an official investigation into its cause.
At the beginning of January, a giant sinkhole appeared in Villerupt, located in the French department of Meurthe-et-Moselle, just a short distance from a residential property. The sudden appearance of the sinkhole prompted the evacuation of nearby residents and sparked numerous questions about its origins. While investigations are ongoing, an expert report has already pointed to several potential causes.
The sinkhole, which spans several metres in width, partially covers both the pavement and the driveway of a house. Initially measured at a depth of 2.5 metres, it has since more than doubled in size. Experts have not ruled out the possibility of a much larger, hidden cavity beneath the surface.
For residents of Rue François Raspail in Villerupt, the discovery of the sinkhole on 2 January was alarming. "We may have narrowly avoided a tragedy," said Pierrick Spizak, the town's mayor. He noted that a neighbour had parked their car in the exact spot where the sinkhole later appeared on 1 January. A school, Paul Langevin, is also located nearby.
The red circle marks the area where the collapse occurred in January. / © BRGM
In response to the collapse, authorities established a safety perimeter, closing the road to traffic and shutting off water and gas supplies to the area. Two houses closest to the sinkhole – numbers 16 and 18 – are now deemed uninhabitable. The elderly resident of number 18 has been rehoused, while the property at number 16 was already vacant at the time of the incident.
Nearly two months into the investigation, preliminary findings suggest a "probably natural" cause for the sinkhole.
"Highly likely" that situation will continue to evolve
A report published on 10 February by the French Geological and Mining Research Bureau (BRGM), obtained by our colleagues from RTL Infos, highlights ongoing concerns about the stability of the area affected by the sinkhole in Villerupt. The document concludes that significant uncertainties remain regarding the cavity's size, shape, and the processes that led to its formation.
According to the BRGM, it is "highly likely" that the situation will continue to evolve, with potential consequences including the widening of the collapse zone and residual subsidence on nearby plots. The report warns that heavy rainfall could accelerate these changes, noting that "the dynamics of evolution could be rapid, particularly after significant precipitation." Given the exceptionally wet weather experienced in recent months, the risk of further instability remains a concern.
One major unknown is the depth of the underground cavity responsible for the collapse, which experts have so far been unable to determine. As a result, the stability of the two houses closest to the sinkhole – numbers 16 and 18 – is not guaranteed. Additionally, the road in front of these properties is described in the report as "considered dangerous."
To address these uncertainties, the BRGM has recommended that a geotechnical engineering consultancy conduct a detailed risk assessment. The study aims to confirm the presence of an underground cavity beneath the street and affected dwellings and propose appropriate measures to fill the hole. Mayor Spizak emphasised the importance of this step, stating that it is crucial to reassure residents, many of whom are understandably anxious about the possibility of the sinkhole expanding. "I'm aware that this is a concerning situation, and neighbours may wonder whether the hole is going to get any bigger," he said.
Did an underground cavity collapse?
The primary explanation proposed in the BRGM report suggests that the sinkhole was caused by "the partial or total collapse of an underground cavity." The area, situated on a limestone plateau (Bajocian limestone), is known to potentially contain karstic cavities. Given the volume of collapsed clay soil and the size of the affected area near the sinkhole, it is hypothesised that a karstic cavity extending beneath properties at numbers 16 and 18, as well as under the roadway in Rue François Raspail, could be responsible for the damage.
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However, the report emphasises the need for caution, as the exact process behind the collapse remains uncertain. "In the current state of knowledge, it is not possible to determine which mechanism is at play," the document states. Several potential scenarios are outlined:
- Rapid emptying of a clay-filled cavity: This could have occurred following an exceptional rainfall event or significant anthropogenic water input, causing the sudden evacuation of clay from the cavity. Heavy rains have been recorded in the region in recent months, compounded by sub-zero temperatures in the days leading up to the collapse.
- Progressive leaching of clay: Another possibility involves the gradual and continuous erosion of clay at deeper levels due to the circulation of groundwater. Over time, this could create a void that rises toward the surface until it eventually leads to a sudden rupture.
- Collapse of a limestone cavity roof: A third hypothesis points to the failure of the roof of a cavity within the limestone layer, causing the overlying soil, including silt and clay, to collapse into the void below.
Criticism on social media
Following the appearance of the sinkhole, social media was rife with rumours and criticism, with many residents questioning whether the local authority's aging water network might have contributed to the incident due to significant leaks.
The BRGM report lends some weight to this concern, stating that the "triggering factor appears to be the water leak at the dwelling identified by Veolia," a French utilities company.
Mayor Spizak confirmed that when the sinkhole emerged, Veolia teams were already addressing a leak in the drinking water network nearby. However, he clarified that the company's intervention may have inadvertently exposed an existing issue rather than causing it. "If Veolia hadn't started digging there, we might not have noticed the subsidence," he explained. "The cavity was already present. Their work simply revealed the problem," Spizak said. It should be emphasised that this remains hypothetical, as the exact sequence of events is still under investigation.
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Another frequent target of criticism has been the operation of a limestone quarry in the neighbouring municipality of Audun-le-Tiche. While acknowledging public concerns, the mayor was careful to qualify his earlier statements. "I never said the quarry caused the subsidence – I'm not accusing the quarry," he stressed. Instead, he posed a question for technical experts: "Could the vibrations from the explosions used in limestone extraction have accelerated a pre-existing instability?"
In the meantime, the mayor noted that an application for recognition of the incident as a natural disaster had been submitted promptly. Pending confirmation, such a designation would support the conclusion that the collapse resulted from natural causes.
It is worth recalling the region's mining history and the extensive network of tunnels beneath Villerupt, which have long posed risks to surface stability. This is not the first such incident in the town. As the mayor pointed out, "In 2020, there was a collapse in Rue Emile Zola, and another occurred in the early 2010s near the Robespierre block of flats." Even further back, in the 1970s, a house collapsed in the same area.
