In February 2013, a surreal disaster struck a 1970s-era house in the town of Seffner, just outside of Tampa, Florida. Shortly after Jeff Bush settled in for the night, his brother Jeremy heard him screaming for help, only to enter Jeff’s room and find that he and all his possessions had been swallowed up by a sinkhole. Jeff Bush’s remains were never recovered, and the sinkhole was filled in—but now, over two years later, the hole has reopened and is around 17 feet wide and 20 feet deep. For Jeff Bush’s family, it brings back unsettling memories, but for the state of Florida, the sudden appearance of sinkholes is something of a familiar problem.
After the devastating sinkhole opened up in Seffner, Hillsborough County bought the property and the one next door, demolished the homes, filled in the hole and fenced off the area. But with the sinkhole filled in, why has it suddenly reopened? Larry McKinnon of the Hillsborough County Sheriff’s Office told ABC News that generally when sinkholes are filled in, they are pretty stable, “so it is pretty rare that it reopened to the extent of this.”
The sinkhole had been filled with gravel, and country officials have said that the company responsible for the remediation will study what happened. But it seems likely that recent rainfall caused the materials in the sinkhole to settle, and in turn, collapse.
Such sinkholes are not an unfamiliar phenomenon; the suburb of Seffner lies within an area of western Florida known as “sinkhole alley.” Indeed, just days after the sinkhole originally opened up in Seffner, another one appeared three miles away. The holes are the result of the fact that Florida is built on a large bedrock of limestone and other porous materials. As acidic groundwater makes its way through the bedrock, it weakens the ground and can cause sudden “cover-collapse sinkholes.”
And this can—as appears to be the case in Seffner—a completely naturally occurring phenomenon. But, there are human activities that have contributed to the occurrence of cover-collapse sinkholes in Florida and beyond. As National Geographic describes: “when you drill a well—looking for water or for mining purposes—as you’re pulling water out of the ground, you’re lowering the groundwater table. That creates almost a toilet-flushing effect. You’re lowering that groundwater level, and the soil that was sitting above just falls out.” Indeed, it was mining endeavors that created a 24-acre sinkhole in Louisiana in 2012.
Alternatively, urban growth can also contribute to the creation of sinkholes. The construction of parking lots and the link can prevent water from naturally seeping into the earth, and instead create a concentration of water in one area that destroys bedrock.
As for Seffner, no one has been harmed or evacuated by the surprise recurrence of this particular sinkhole, but it has reminded local residents of a persistent concern and a recent tragedy.
Images screengrab via AP