Florida tragedy: So what makes a sinkhole open up?
Your support helps us to tell the story
From reproductive rights to climate change to Big Tech, The Independent is on the ground when the story is developing. Whether it's investigating the financials of Elon Musk's pro-Trump PAC or producing our latest documentary, 'The A Word', which shines a light on the American women fighting for reproductive rights, we know how important it is to parse out the facts from the messaging.
At such a critical moment in US history, we need reporters on the ground. Your donation allows us to keep sending journalists to speak to both sides of the story.
The Independent is trusted by Americans across the entire political spectrum. And unlike many other quality news outlets, we choose not to lock Americans out of our reporting and analysis with paywalls. We believe quality journalism should be available to everyone, paid for by those who can afford it.
Your support makes all the difference.Imagine a limestone gorge. Look back in time and imagine it covered over. And then think what happens at some time between the two. Imagine standing above ground at that stage and discovering the first hole in what was then a cavern 'roof' when the ground opened up. And you're thinking of a sinkhole.
Limestone is slightly soluble, allowing water to disappear underground where it erodes away rocks to form huge caverns - and those open into huge holes or gorges as the roof gives way.
Sinkholes - sometimes known as snake holes and swallow holes - also occur in sandstone and where underground water moves away soil. They occasionally have man-made causes, such as mining. The holes might be a metre wide and deep - or hundreds of metres across and down.
Anyone who has been to Malham Cove in North Yorkshire can imagine the process clearly as they look up the gorge to where the stream emerges from the base of the limestone cliff, standing where once was a huge cavern.
Although these voids may form very gradually they often appear suddenly when the final crust gives way - and that is what seems to have happened in Seffner, Florida, where a 6-metre hole opened up beneath the home of Jeff Bush.
“There's hardly a place in Florida that's immune to sinkholes,” said Sandy Nettles, who owns a geology consulting company in the Tampa area. “There's no way of ever predicting where a sinkhole is going to occur.”
Most sinkholes are small, like one found Saturday morning in Largo, 35 miles (56 kilometers) away from Seffner. The Largo sinkhole, about 10 feet (3 meters) long and several feet wide, is in a mall parking lot.
The state sits on limestone with a layer of clay on top. The clay is thicker in some locations - including the area where Jeff Bush became a victim.
Jonathan Arthur, the state geologist and director of the Florida Geological Survey, said other states sit atop limestone in a similar way, but Florida has additional factors like extreme weather, development, aquifer pumping and construction. “The conditions under which a sinkhole will form can be very rapid, or they can form slowly over time,” he said.
What specifically caused the Seffner sinkhole? No-one can be sure.
“The condition that caused that sinkhole could have started a million years ago,” Nettles said.
Staff and AP
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies
Comments