Apple #242: Sinkholes

I was reading an article about the Dead Sea and how it's shrinking, and how they're trying to divert water from the Red Sea into the Dead Sea to keep it from evaporating. The article also said that one of the reasons they don't want the Dead Sea to keep shrinking is because sinkholes keep opening up around it. The article described how sinkholes formed, but it was either confusing or I wasn't paying attention, or anyway I didn't really get it. So I've decided to find out how sinkholes form.


One of the sinkholes near the Dead Sea.
(Photo from the Geological Survey of Israel)

• Where it rains, or any place there's a body of water, some of that water will soak into the ground.

• The farther the water soaks into the ground, the more acidic it becomes as it travels through the soil.

• Eventually that acidic water is going to hit rock beneath the soil.

• Depending on where this is happening, that rock might be a salt bed or it could be limestone or some other type of soft rock. If that's the case, that acid-laced water will erode and crack the soft stone beneath the layers of soil.

The early stages of sinkhole formation, when water is eroding the limestone beneath the soil and forming water pockets.
(Diagram by USGS, sourced from U of Florida)

• Over time, the water carves out such a big space in the underground rock that pools or even small lakes of water form in the rock.

• Eventually, that space in the rock becomes too big for the soil and other rock above to keep acting as a ceiling, and the pressure of the rock and soil above will make that surface material collapse into the hole.

A sinkhole, post collapse
(Diagram by USGS, sourced from U of Florida)

• Thus a sinkhole is born. Or more accurately, thus it is revealed to those of us living on the surface.

• In the United States, Florida and the area surrounding the Texas panhandle are the places where sinkholes are most likely to form.

• One day in September 1999, a sinkhole opened up beneath Lake Jackson in Tallahassee, Florida. Within a few short days, the entire lake and everything in it -- fish, alligators, plants, frogs, everything -- drained down the sinkhole.

"It was spectacular," said Jess Van Dyke, a regional biologist for the State of Florida who was on the scene when it happened. He saw "animals trying to scramble out, a whirlpool of gators, birds and bass went down the hole."

• It is now possible to walk across the entire dry lakebed from shore to shore.

A house in Florida completely sunk in a sinkhole
(Photo from the Southwest Florida Water Management District)

• Some sinkholes persist for a long time once they've opened up. One famous sinkhole that harbors a complete ecosystem is Montezuma's Well near the Grand Canyon in Arizona.

• Another enormous sinkhole -- the world's deepest -- is in Mexico, and it happens that NASA is sending a robotic explorer into it this week. The sinkhole is called Zacaton, and it is 282 meters deep. While divers have made the attempt to reach bottom, they have not succeeded and at least one person died trying. This will be the first time anyone will see what is down there at its deepest point.

Montezuma's Well, a sinkhole that's been around a long, long time.
(Photo sourced from Ron's Log about life in the desert)


EDIT:  At the end of May 2010, tropical storm Agatha caused all kinds of flooding and mudslides and various other rearrangements to the landscape in Central America.  One of those rearrangements was a giant sinkhole that yawned in the middle of Guatemala City.  There was another a sinkhole that opened up in Guatemala City in 2007.  That one was estimated to be 300 feet (100 meters) deep.

This 2010 sinkhole is a brand new one.  It's only about 3 miles away from the old one.  A three-story house that was used as a clothing factory fell into it, and according to CNN, a security worker fell into it and died, though his death has not yet been confirmed.  The reason there were no casualties from when the clothing factory fell in is because everyone had left work about an hour before the sinkhole appeared.


Sinkhole in Zone 2 of Guatemala City, 2010
(Photo from Trending Daily)


As of June 1, scientists are estimating that the new sinkhole is about 66 feet across and 100 feet (30 meters) deep, or only about 1/3 as deep as the 2007 sinkhole.  It's probably only the angle from which the photographs were taken, but the new one looks even scarier than the old one.

It's not that obvious in the photo I have here, but that building with the greenish-blue front is teetering over the hole.

Here's what the 2007 sinkhole looked like:

2007 sinkhole in Guatemala.  The two look very similar, don't they?
(Photo from News Junkie Post)


The 2007 sinkhole opened up because of a ruptured sewer line in the city's sewer drainage system.  They're not saying yet what caused this one, though speculation has included the possibility that it could be the sewer system again, or that the sinkhole touched down into a massive underground cave.  City officials also don't know yet how they'll attempt to fill the hole.


Sinkholes in Popular Culture

• Because a sinkhole opens up when the pressure from above gets to be too great, that means that a person walking over a secret sinkhole could trigger its collapse and fall when the thing caves in. This strikes me as ripe material for a horror movie and leads me to my next question: have there been any books or movies that use sinkholes?

• Star Wars - Episode III, Revenge of the Sith - Obi-Wan Kenobi leads a battle against the general of the droids on the edge of a sinkhole on the planet Utapau.
  

• A movie called Sinkhole was released in 2003, but it seems to refer to sinkholes as more of a concept than actual items or plot events.

• On Hostile Ground, which was a TV movie from 2000, is about a city worker and her geologist friend (John Corbett) who try to keep New Orleans from having its annual Mardi Gras parade because a giant sinkhole is growing ever larger and collapsing all the city's sewage tunnels.

• A sinkhole does appear briefly in Gothika, but that movie makes insanity rather than sinkholes its star. A sinkhole also opens up in the War of the Worlds, but I suspect that movie uses anything and everything they could render in CGI.

• Seems like some untapped potential is lurking in sinkholes, all you horror writers out there!

Sinkhole that opened up beneath a garbage truck in Toronto in 2006
(Photo posted at Stormchasers)

• I did find sinkholes appearing in other media:

• Quad Desert Fury - Gameboy game. Race your ATV over the desert and avoid sinkholes to beat the competition.

• There's a song called Sinkhole by a punk band named Fifi. The lyrics in this sample are: "The city's gonna fall / the city's gonna fall / the city's gonna fall into the sinkhole."

• And there's a band called Sinkhole. They have three CDs (two plus a compilation), which include songs such as
  
• Fudge Bar
• Burning, Itching, Irritation
• Smell Isn't Everything
• Go Ahead, Eat My Pretzels

You could make the argument that somebody who eats all your pretzels is like a sinkhole.


Sources
Southwest Florida Water Management District, Sinkholes brochure
US Geological Service, Water Science for Schools, Sinkholes
University of Florida, Plant Management in Florida Waters, Sinkholes
Jake Page, Dragonfly Dramas, Smithsonian Magazine, January 2002
Desert USA, Montezuma's Well: A Living Oasis

2010 sinkhole news
Crews probe Guatemala sinkhole as neighbors flee, Associated Press, June 1, 2010
Ezra Feiser, Guatemala City sinkhole so big, so round it "doesn't seem real," Christian Science Monitor, June 1, 2010
Ker Than, Sinkhole in Guatemala: Giant Could Get Even Bigger, National Geographic Daily News, June 1, 2010
Tropical Storm Agatha blows a hole in Guatemala City, The Guardian, June 1, 2010
Guatemala Sinkhole: The Guatemala Crater that's making news, Trending Daily, May 31, 2010
Ole Ole Olson, Massive Sinkhole In Guatemala Created By Tropical Storm Agatha, News Junkie Post, May 31, 2010
Ole Ole Olson, 2007GuatSink, News Junkie Post, May 31, 2010
Guatemala Sinkhole: Giant Crater Opens in Guatemala City, Long Island Press, May 31, 2010