There’s no direct link between fracking and sinkholes.

Other oil and gas activities, such as drilling and wastewater disposal, cause them. Since fracking leads to earthquakes, it’s reasonable to assume that’s also how sinkholes form under the right conditions. What causes sinkholes, and what can be done about them? 

Who’s at Fault? 

Fracking — short for hydraulic fracturing — involves injecting high-pressure fluid into the ground to force open fissures for oil or gas extraction. It’s one of many oil and gas extraction methods, with others including vertical and horizontal drilling.

It's important to state that fracking can increase the pressure along a fault plane, a flat, underground rock surface that can slip out of place and cause an earthquake. Injecting the ground with salty wastewater — a byproduct of fracking — also causes quakes along fault lines, where fault planes intersect.

Fracking and wastewater disposal have become notorious for increasing seismic activity worldwide. The central and eastern United States averaged 21 earthquakes per year before 2000 but experienced over 300 annually between 2010 and 2012. The main cause was high-pressure wastewater disposal. 

What Causes Sinkholes? How Sinkholes Form

Sinkholes are partly caused by a natural erosion process where acidic water percolates through underground bedrock. As rocks and soil fall into the void, the water carries them away from the area and creates an underground cave. 

It isn’t just Mother Nature opening voids in the Earth. Other processes that contribute to sinkholes include drilling, mining, collapsing sewer systems and groundwater extraction that lowers the water table. Fracking may also cause sinkholes by generating earthquakes, which are known triggers for their formation. 

The second part of how sinkholes form is when the surface layer of the ground collapses. As the underground cave grows bigger, its roof gets weaker until it finally gives out. It may collapse under its own weight or break in the presence of added weight, like cars or houses. The cave roof is usually very thin when it falls in on itself.

Sinkhole de Mayo 

A sinkhole opened up in Daisetta, Texas, in May 2008, swallowing several vehicles and oil tanks. Some residents jokingly referred to the event as “Sinkhole de Mayo,” a reference to the Mexican holiday. Still, its proximity to homes and the local high school prompted concern. This April, a second sinkhole developed alongside it, renewing fears that the town was in danger. 

Daisetta sits on an underground salt dome. The one under Daisetta is a rich oil and natural gas reservoir, making it an attractive drilling site. However, salt is a very unstable material on which to build homes. Drilling along a salt dome can cause it to break down or collapse completely, which is one way sinkholes form. 

In 2012, a sinkhole opened up over the salt dome near the community of Bayou Corne, Louisiana. Texas Brine Co. had been using the area for oil and gas storage when an underground cavern began collapsing. Residents had to evacuate their homes, and today, Bayou Corne is a ghost town. 

Fracking and Sinkholes

Daisetta still has a population of just under 1,000 people, but further seismic activity could prompt an exodus. Residents might also embrace the sinkholes, as is the case in Wink, Texas.

The Wink Sinks are a pair of sinkholes in Winkler County, an area pockmarked by decades of oil and gas drilling. The first sinkhole sits on an old oil well site and the second occupies a former water supply well. Residents are technically forbidden from visiting the sinkholes, but many people wander close despite the warning signs. 

Both holes collapsed due to downward freshwater seeping through boreholes and cracked cement casing near the wells. Fracking and sinkholes still aren’t definitively linked, but drilling and wastewater disposal are known culprits. It may only be a matter of time before scientists conclude that fracking and sinkholes go hand in hand. 

The Role of Earthquakes

Fracking may cause the ground to collapse, leading to earthquakes, a well-known trigger for sinkholes. In 2021, a massive earthquake in Croatia created nearly 100 of them in an area measuring just 3.8 square miles. 

These geological formations — known as cover collapse sinkholes — usually occur where water has hollowed out underground rock to form cavities. The surface layer consists of sand or alluvium, clay and soil. As the water transfers surface material into underground voids, the surface layer becomes structurally unstable and eventually collapses. The presence of clay soil makes it hard to detect this process until it reaches its inevitable conclusion.

Earthquakes themselves don’t cause sinkholes to develop — other processes must carve out the underground void. Instead, tremors trigger the roof collapse, which is the final step in sinkhole formation. Therefore, even if fracking generates a sinkhole-triggering earthquake, it technically wouldn’t have formed the sinkhole in the first place. Instead, it knocked over the proverbial domino to set it in motion. 

Whether such a verbal loophole matters is debatable. This technicality may allow oil and gas companies to issue statements that fracking doesn’t cause sinkholes, leading to beliefs that the two are unrelated. That could affect how people vote on the issue. 

Although oil and gas companies occupy a political stronghold in many parts of the world, their grasp is beginning to slip as more people transition to renewable energy. Drilling and fracking for fossil fuels don’t just shake up the ground — it’s also unsustainable in the long run and causes environmental damage. As uneven oil reserves create a volatile market, many nations embrace wind, solar and geothermal power. 

Does Fracking Cause Sinkholes? 

So far, no studies have found direct evidence linking fracking and sinkholes. Scientists need more data to reach a conclusion, and nobody wants to make connections if they don’t exist. 

Fracking may be a part of what causes sinkholes because drilling, saltwater injection, hydrocarbon extraction, and other oil and gas activities can lead to them. Fracking also definitively triggers earthquakes. That’s enough reason for people living near sinkholes to be wary of hydraulic fracturing and keep an eye on potential developments.