Sinkholes have been reported across the world, causing problems for local communities from Greenwich to Guatemala. A common geographical region for such events is the UK. These cracks in the surface – creating voids of varying sizes – are often the product of climate change.
This weekend, the historic city of St. Albans, in the U.K., saw a major road suspended due to the appearance of a sinkhole, revealing a void beneath the road. This is to the extent that the void poses a risk to cars and pedestrians.
Sinkholes
A sinkhole is a type of void that has no natural external surface drainage. Basically, this means that when it rains, all of the water stays inside the sinkhole and typically drains into the subsurface over time dissolving the rocks beneath. This creates underground spaces and caverns.
Sinkholes can be saucer-shaped or appear deeper, more like shafts. If they occur in built-up areas, they can appear more irregular as a road or another structure above can distort the shape.
Voids
An alternative name for the cavern expanding beneath the road is a ‘void’. The term is often reserved for a hole smaller than a sinkhole, but one no less significant. These voids are gaps below the surface in the land, a form of subsidence, as represented by the downward movement of the ground beneath the road surface as a result of the soil being compressed by the weight of materials above (including vehicles, buildings and trees).
Voids, sinkholes and subsidence can often cause problems without any warning, their causes may not be immediately obvious and their extent not known until extensive investigations have taken place. This is especially so in the UK.
What is a sinkhole?
Sinkholes are often saucer-shaped holes that occur as the result of a collapse or removal of an underlying layer of rocks that is used to support the materials on the surface, as Sky News has reported.
The shape of a sinkhole depends on the composition of the rocks underneath the surface and the different interacting processes taking place. It is thought, by scientists, that many common sinkholes are often the result of the removal of a soluble rock such as chalk, gypsum or limestone during the construction of roads. These are classed as solution sinkholes.
Hence, the main trigger for sinkholes is water. In such cases, water gradually dissolves soluble rock, forming a cavity under the ground. Subsequently, loose sedimentary rock from nearer the surface level gradually falls into the cavity, until the surface is unable to sustain itself any longer and collapses.
Climate change
The steady march of climate change raises the likelihood of extreme weather, especially torrential rain and flooding conditions, are connected to the exposure of sinkholes. This is something set to become increasingly common.
St. Albans event
With the St. Albans incident, Liberal Democrat County Councillor for St Albans South, Sandy Walkington, has responded to concerns, explaining what he understands thus far. This is in relation to ‘voids’, a breakdown of the hard roadway and an increasingly common event in the UK.
While UK sinkholes are common, most are realtively shallow and of a reduced diameter. Sinkholes in the UK are rarely more than a few dozen feet deep, dwarfed by the likes of the Red Lake in Croatia, which, at 1,740ft, is Europe‘s deepest sinkhole.
As an example, in 2015, chalk excavation underneath the clay pit was attributed as the likely cause of a sinkhole in St. Albans. That was then, this is now – what is causing the events in 2025?
“Due to the safety concerns surrounding voids, the decision has been made to close off the road whilst the relevant information is received from the utility companies, and a team is organised to break open the surface safely for further investigation,” Cllr Walkington explains.
On this subject, The Guardian‘s Karl Mathiesen states: “Anything that has the potential to divert water into weak points beneath the earth will accelerate the creation of the pits into which houses, cars and unfortunately people sometimes fall” .
The Automobile Association, the major road breakdow organization,suggests the road is St. Albans road currently shut is due to “emergency repairs” on Verulam Road “in both directions from A1081 Chequer Street to Upper Dagnall Street. This underestmates the wider context and significance of the event.
Predictions
While the road closures associated with St Albans prove to be an inconvenience, the advancing rate of sinkholes is causing mayhem. At the heart, wet weather leading to saturated ground is the primary catalyst for the appearance of natural sinkholes in the UK.
Ruptured pipes, abrupt sinkholes, hanging railtracks and fallen bridges can seriously compromise public safety and the environment. At the heart of many of these events is climate change, the direct consequence of human activity.
Because they are usually caused by the erosion of bedrock, sinkholes form more easily in areas that stand on chalk, gypsum or salt rock, which dissolve quicker than other types of ground. As well as making the southeast more prone to be hit, this also makes the Isle of Wight and parts of Yorkshire more vulnerable.
