Apple #639: Geothermal Mud Pots

I'm starting with a preamble.  If you want to, you can skip it and go straight to the geothermal mud pots (a.k.a. the good stuff).


Geothermal mud pot at Yellowstone.
(Photo by Christian Begeman)

Coughing in the Middle of the Night & Being Speedy

For the past several nights, I've been waking up in the middle of the night coughing.  It's been driving me nuts.  I Googled the problem, and it turns out this is pretty common.

(Side note: I didn't want to do a Daily Apple on this because I've learned the hard way that medical problems can have so many possible causes, the entry very quickly becomes less than useful, and then people post questions about their own medical situation, and not being a doctor, I have no business giving advice even if I knew what to say.)

But based on what I read (the best source I found on the subject is Harvard Medical School's page), and based on my personal situation, my coughing is probably due to the most unpleasantly phrased post-nasal drip.  The liquid from the nose slides down to the throat while you're asleep and triggers a cough.

I've so far tried various home remedies: sleeping on a propped up pillow, a tablespoon of honey before bed, gargling with saltwater, using a Neti pot.  In spite of all these things, I still wake up coughing.  So now I'm trying another suggestion, which is a nasal decongestant.  I hate these things because whether they say non-drowsy or may make you drowsy or whatever, they make me so speedy I can't sit still.  I've only tried one or two of these types of things in my life and I can't remember which ones I've tried, so I picked one off the shelf pretty much at random, and now here I am all twitchy and itchy and speedy from the stupid stuff.  What's more, I still keep having to blow my nose.

So it's probably going to be a long night.

And I'm probably going to be extra-wordy in this entry.  You've been warned.

Geothermal Mud Pots

Mud pots in action near Calipatria, CA.
(Photo from flickriver)


I was trying to decide on a topic for this week's Daily Apple.  Naturally, I thought some type of natural disaster might make a good post.  I've covered hurricanes, earthquakes & tsunamis, thunderstorms, and derechos, and while I haven't done an entry on volcanoes in general, I did do one on Mount Etna.  I have not done an entry on tornadoes, but I did sort of mention them in last week's entry on why Oklahoma has no basements despite being practically a magnet for tornadoes. So I thought something other than tornadoes would make a nice change.

So I cast my mind back to junior high science classes and the movies the teachers used to show us about natural disasters and earth science.  Earthquakes, volcanoes, etc.  The volcanoes were my favorite part, but another really good part was about the geothermal mud pots.  Everyone in the class got a huge laugh out of seeing those things spew mud and make all sorts of rude noises.  Then we'd beg the teacher to please please please run the film backwards (you kids with your DVDs and your VCRs will never know such delights), and if he was in a good enough mood, the teacher would do it.  Oh, the hilarity.

OK, so let me show you some videos of these geothermal mud pots, and then I'll find out some facts about them and pass those facts along to you.

This one is from Kamchatka, Russia.  The sounds still make me giggle.  Completely juvenile humor, I know.




Here are some closer to home in Salton Sea, California:




This one shows the mud pots across a whole area:




Now for the facts, ma'am.

• Mudpots are one kind of geothermal activity. Hot springs and geysers are similar, but they each have slightly different characteristics.

• Here's how geothermal stuff happens:

• Beneath the crust is a layer of magma, or hot molten rock.  The movement of the plates that form the earth's crust or volcanoes can force the magma closer to the crust.  

• If the magma shoots up through the crust, you get volcanoes.  When groundwater comes in contact with the magma and the resulting steam shoots up, then you get geothermal activity.

• Hot springs happen when the steamy water coming up from below forms a pool. Usually the water contains various minerals that come from the magma.  Hot springs are usually not that hot but only warm, so sometimes people like to bathe in them.

• If the water doesn't stay in a nice calm pool but shoots up like a fountain, then it's a geyser.  A whole lot of pressure is required to make the steam shoot up like that, so usually there's a huge underground network of twisting and turning tunnels that hold the groundwater and keep the pressure building until finally the thing spouts off.

(Encyclopedia Britannica has a really great diagram that illustrates this whole process for hot springs and geysers. I can't embed the link here for copyright reasons, but it's worth the click to see it.)

• Mud pots are similar to hot springs in some ways.  Usually the steam coming up isn't jet-propelled like a geyser but only bubbling to the surface.  It's often not super-hot but only warm.  Mud pots may also form pools, as hot springs do.  But there are two major differences.  

• In mud pots, the steam coming up from below also contains sulfuric acids that erode the surrounding rock.  The rock turns to sand and clay and that mixes with the water, making mud.  

• The sulfuric acid also means that most mud pots have a definite odor about them, like the smell of rotten eggs.

• The material surrounding the mud pots often also includes volcanic ash, or rocks that have been formed from volcanic ash (i.e. pumice).  When water interacts with the ash, or when the acidic water hits the pumice, it makes bubbles.  When the bubbles rise to the surface, they burst and fling the mud in all directions.

 I know you want to see more.

• Mud pots can change  in character as the amount of water varies.  If there's a lot of groundwater, the water can overwhelm the mud and it becomes more like a hot spring.  If there's too little water, the mud pot will dry out and it becomes only dry, cracked earth with steam venting from it.

• Mud pots can also turn into what people call mud volcanoes, or mud domes, or mud gryphons (< 3 meters tall).  The mud can pile up around the opening of the mud pot, getting taller and taller while the muddy steam still keeps spewing out.

• The steam coming up from the volcanoes is often hotter than what's in the mud pots

 
Mud volcano, or mud gryphon, at Salton Sea
(Photo from Toadhaven Home School)


Video of a mud volcano in action, followed by some dry mud pots issuing steam. Please also enjoy the videographer's Midwestern accent.

• A geothermal power plant has been built near these mud pots at Salton Sea, and some people say the mud pots are no longer as active or fun to watch.

• Some mud pots also have other minerals such as iron oxide, potassium, or magnesium which give the mud color.  Those mud pots are typically called paint pots.  Paint pots have no sulfur.  If they did, the sulfur would turn the mud gray.

In part of this video, the mud is pink. That's a paint pot.





An especially vibrant paint pot at Yellowstone.
(Photo from Globus Journeys)

• All these mud pots will vary from one season to another, and from one year to the next.  Over time, they may change a lot, even dry up completely.  Some people say the mud pots at Yellowstone don't look anything like they used to.  A geothermal power plant was built near the Salton Sea mud pots to harvest some of the geothermal steam coming up in that area.  As a result, the mud pots there are reportedly nowhere near as active now as they are in the videos shown here.

• But there are mud pots in lots of places in the world.  There are some in New Zealand, some in Iceland, and some in Costa Rica.  Who knows, some others may pop out in new places, too.

Mud pot in Iceland, and some steam vents. (This video is pretty loud.)





Sources
Home Science Tools, Geysers
Janice Kleinschmidt, Sea of Wonders, Palm Springs Life, March 2006
Geothermal Features, Mud Pots
National Park Service, Yellowstone, Mudpots and How They Work

Apple #524: Mount Etna

I check weather.com frequently.  It's a wellspring of information.  Today, I learned from that uber-useful site that Mount Etna erupted recently.  So I thought I'd find out more about the volcano.

• As of this writing, Etna's most recent eruption happened on Thursday, May 12, 2011.

• Etna is one of the most active volcanoes in the world.

Etna is a volcano on the island of Sicily, which is south of Italy.  It's about ten miles from a town called Catania, whose citizens have been dodging Etna's lava for centuries.
(Map from geology.com)

• Eruptions have been documented as far back as 1500 B.C. and it has erupted more than 200 times since then.  

• Scientists think it originated underwater.  It has erupted so many times, it's now above sea level.

• Notable eruptions include one in 1669 that marked people's first efforts to try to control the flow of lava, but the lava made it all the way to the town of Catania and the sea as well.  It killed somewhere between 60,000 and 100,000 people.  After that disaster, artificial attempts to stop the flow of lava were outlawed until the 1980s.

From a fresco in the cathedral at Catania depicting the eruption of Mount Etna in 1669. There are two vents shown here, the smaller of the two with a 9 kilometer-long fissure extending from it.
(Image from U.C. Davis)

• Another notable eruption happened in 1852 when the volcano spewed forth more than 2 billion cubic feet of lava that covered more than three square miles of land nearby.

• In 1979, Etna began an eruption that would continue for 13 years.

• In 1992, people tried to control the lava flow again, this time by using explosives to make a hole beneath the lava tunnel and then dropping huge concrete blocks into the hole to try to stop it up.  Like the effort in 1669, this was unsuccessful.

• Etna's most recent series of eruptions started in 2007 and is considered to be "ongoing."

Etna's eruptions are so common that this recent outburst was described in the media mainly in terms of whether it might affect this year's Giro d'Italia.  Cycling fans were assured that the race would go on as usual, with the eruption acting as a picturesque backdrop.  Officials did have to close the airport in Catania for a while, though.
(Photo from the AP via the Daily Telegraph)

• Scientists aren't exactly sure why Etna erupts as often as it does and where it does.  They have proposed lots of theories but none quite fit the data.  But Etna's behavior is probably related to the fact that it's located right where the African tectonic plate meets with the Eurasian tectonic plate.

• Its unusual behavior may also be related to the fact that Etna is actually two volcanoes, one on top of the other.  The bottom volcano is a shield volcano.  The one on top is a more recent stratovolcano.

• Shield volcanoes are usually huge in diameter, not that tall, and with broad long sloping sides that are built of many layers of lava flows.  Mauna Loa in Hawaii is the world's largest shield volcano.  Typically, the lava flows that come from these are relatively slow-moving.  The lava may also escape from fissures along the flank of the volcano, rather than exclusively from the central vent.

Lava that flowed down from Mount Etna to the town of Nicolisi in July 2001.
(Photo from Getty Images via National Geographic News)

• Stratovolcanoes, on the other hand, are more cone-shaped, rise higher into the air, and are made up of layers of lava flows, mud flows, and pyroclastic material (I'll define that word in a minute). Mt. Fuji is the most notable type of stratovolcano.  

• Stratovolcanoes are often the most deadly variety of volcano.  They are usually located at the convergence of two tectonic plates.  In most cases, stratovolcanoes are dormant for long periods of time, as the energy from the movement of the plates beneath builds up.  When stratovolcanoes do erupt, their eruptions are usually very explosive, powerful, and deadly.

• One of the things that makes stratovolcanoes so dangerous is their creation of pyroclastic materials.  These are huge chunks of magma and rock that get blown to bits when a lava explodes.  The pyroclastic materials may range in size from rocks the size of a fist, to pebbles smaller than a dime, to ash. 

• "Some of them are bigger than cars, and some might be as big as trucks," said one volcano watcher of the boulders coming out of Etna this week.

• In spite of Etna's dual-volcano personality and its potential to cause a lot of damage, the fact that it erupts so frequently probably keeps it from being that much of a threat.  More dangerous stratovolcanoes hold in their energy for decades until it explodes and it's all released at once.  Etna's regular release of energy and gases are probably why it's not considered a pressing danger to people living in nearby Catania.

• 2010 was a relatively quiet year for the volcano. When it erupted in January 2011, vulcanologists expected that it would continue erupting this year pretty much continually, maybe for weeks or months at a time. This eruption is confirming that expectation.

Lava flows from Mount Etna's eruption in January 2011
(Photo from National Geographic News)


An eruption on the flank of Mount Etna in 2007.
(Photo from Earthweek)


An especially pyrotechnic eruption from Mount Etna.  I don't know what year this was taken.
(Photo by Luke and Alyssa Meyr, sourced from MIS Blue Team Science)

•  "Etna" is Greek for "I burn."  Seems aptly named, doesn't it?

Sources
The Sofia Echo, Mt Etna in Sicily erupts, international airport closed, May 12, 2011
The Daily Telegraph, Volcanic threat erupts as Francisco Ventoso wins sixth stage of the Giro d'Italia, May 13, 2011
Brett Israel, Mount Etna blasts lava, ash into the sky, OurAmazingPlanet via MSNBC News
ABCNews, Volcano Chasers at Mt. Etna
Mt. Etna erupts "like cannon" 6 tourists killed, 23 injured, The Montreal Gazette, September 13, 1979
Jessica Ball, Geology.com, Mount Etna - Italy 
San Diego State University, Department of Geological Sciences, Shield Volcanoes, Stratovolcanoes
USGS, Shield Volcanoes
Solcomhouse, Mount Etna

Apple #512: How Earthquakes and Tsunamis Happen

So with all the recent articles and conversations about the enormous earthquake that Japan suffered at the end of last week, there's been lots of talk about plate tectonics.  Plates of the earth's crust shifting and bumping into each other.  People are using words like subduction and convergent plates and all sorts of stuff like that.  Even though I studied earthquakes in school like everybody else, I'm having a hard time visualizing the complete process by which an earthquake occurs.  So, like a good Apple Lady, I looked it up.

Because it's a process, static diagrams weren't very helpful to me.  I wanted animations.  Drawings in action, with arrows and helpful identifiers to show me what's happening, to show me how the stuff under the crust can build up, or how an earthquake can send shock waves through the ground.  So I went looking for lots of videos.

I found some helpful stuff.  I'm going to give them to you from basic and general to more specific, zeroing in on what happened in Japan, first to create an earthquake, and then to create the tsunami.


Plate Tectonics Basics

Basically, the earth's crust is a series of floating flat islands of rock, or plates. The plates are sliding around on top of molten rock. As the plates bang into each other or drift apart, the shape of the landscape changes. Mountains might form, or volcanoes could form and erupt, or earthquakes could happen.

In this animation, the process ends with the creation of a volcano:





Types of Plate Movements and Boundaries

As the hunks of the earth's crust are floating around, they bump into each other or interact with each other in different ways. Sometimes they float away from each other (diverge), sometimes they bump into each other (converge), and sometimes they rub against each other (transform).

This presentation shows how the plates can interact with each other to create different results. Specifically, it describes the various types of boundaries and what happens to the crust in each case:




This soundless animation focuses specifically on what happens as the crust on one plate is forced beneath another.  This process is called subduction.  As shown here, the crust that gets pushed down into the hot magma gets melted and eventually bubbles back to the surface in the form of volcanoes:




The voice-over for this one is in French, but the images are still helpful, I think. This animation shows plate movement at the bottom of the ocean. First it shows what happens when plates diverge, and then it shows convergent plates where one is subducted beneath another and volcanoes and mountains form as a result -- all at the bottom of the ocean:





Earthquakes in the Ocean Creating Tsunamis

The process by which volcanoes are formed is very similar to the process by which earthquakes are created. The difference is, instead of one plate happily subducting another below it to be melted and turned into a volcano, the plate getting butted against pushes back or rebounds, and that causes an earthquake.

This animation shows an oceanic plate pressing against a continental plate until an earthquake results. There's no sound, but explanations are included in text along with the animation:




This is an animation of the earthquake and subsequent tsunami that happened in Sumatra in 2004. It shows one oceanic plate pressing against a continental plate. The passage of time is indicated in the right hand corner. The pressure builds up until finally the continental plate pushes back, so to speak, creating an earthquake.  By the way, the speed with which the "island pops up" is deceptively fast.  In real life, that would take many years.

But this is the closest depiction I could find of what happened in the earthquake in Japan:




Tsunamis

Compared to the creation of an earthquake, the process by which tsunamis occur is relatively simple. Also, since they are in effect reactions to earthquakes in the ocean, they happen much more quickly.  But because so much water is involved, they can be far more destructive than the earthquakes that created them.

Quick & dirty overview of how a tsunami is formed:




I can't embed this next video, but I can give you a link.  This meteorologist's animation isn't great, but his explanation is helpful and it's a more complete explanation than the animation immediately above.


This guy with a British accent explains pretty much the same thing as the American meteorologist.  His images are rather static and though they're kind of hard to read, they're actually more descriptive than the meteorologist's. This guy also goes on to talk about where tsunamis tend to be more common:





This animation generated by NOAA shows the path(s) of the tsunami following the earthquake in Japan.  Suddenly the Pacific Ocean seems much smaller:




Here's another graphic from NOAA, this one static.  It shows the intensity of the tsunami that started at its originating earthquake off the shore of Japan.


The black triangles, I think, are tide gauges. The black lines are "computed tsunami arrival times."
(Graphic by NOAA, sourced from dose.ca)


Pretty intense.  All of it courtesy of the seething hot mass that is the mantle beneath our feet.

If you want to know more about how tsunamis work, read this brief article by Jeremy Bernstein, a physicist and regular contributor to the New York Review of Books.  It's descriptive without being too technical, informed without being stuffy.  Good stuff.
(Thanks, regular reader Jason, for the link.)

Apple #402: Oceans

Ladies and gentlemen, I have a new love. It's a book.

It's really cool and also beautiful, it's always at hand when I need it, yet it doesn't interrupt when I want to do something else. We never fight. Best of all, it teaches me something new all the time.

The book is called Ocean: The World's Last Wilderness Revealed, and it is huge.



It is 12" x 10", 512 pages, and nearly 6 pounds, to be exact. It is so big because everything you could imagine having to do with oceans in any way is discussed and described and photographed in this book. Every page is in full-color, photographs galore. There are atlases of the oceans. There are explanations of ocean currents, of plate tectonics, and of salt farming. There is a fully illustrated guide to species, from bacteria and protozoa, to sponges and molluscs, to birds and reptiles and mammals.

Each page has one huge photograph of something spectacular -- a gigantic fish, for example -- and then surrounding the large photograph are smaller photographs of related things -- smaller fish or similar fish or fish that live in the same region -- with paragraphs of explanatory text around them. So each page is chock full of information and really cool things to look at besides.

Here are some of the facts I've learned so far:

• Oceans are the largest habitat on earth. Yet because of the depth of the water, we know very little about them. We have better maps of the moon.

See? Look at all that ocean.
(Photo from Kennesaw University)

• (It may no longer be true that our maps of the ocean floor are not so great. Google Earth has recently finished using its satellites to render maps of the ocean floor.)

• Free divers pooh-pooh the oxygen tank. They simply hold their breath. The deeper they go, the more their lungs get squeezed by the pressure of all that water above them. But at the same time, their blood vessels expand, so they're all right. Some free divers have gone as far as 600 feet deep -- that's on one gigantic breath.

• 600 feet might not seem like much. But compare this: in 1960, two guys took their ocean diving craft called the Trieste into a really deep part of the Mariana Trench -- the deepest place on earth. They dove down 35,797 feet. In their powered craft, it took them 5 hours to get down there. No one else has dived as deep since.

• There are mountains on the sea floor. These are called seamounts, and they have to be at least 3,300 feet tall to qualify (El Capitan in Yosemite is 3,300 feet tall). Yet they are completely submerged. There are some 100,000 of them on the ocean floor.
  

• Lobsters migrate. On their spiky little arms, they walk in single file across the ocean floor.

• There's a place on the coast of Namibia called the Skeleton Coast where the desert goes right into the sea. I mean, the ocean waters are lapping against the desert sands. This seems to defy all logic. You would think that all that ocean water would rain down on the coastline and water that desert, but no. It condenses into a near-permanent fog, the wind usually blows off the water into the ocean, and the desert stays desert.

The Skeleton Coast
(Photo by Pepix2007 on Flickr)

• It is called the Skeleton Coast because all that fog and the high winds and the overall insanity of the place make it very hard for ships to navigate, and countless ships have run aground there. Survivors who make it to land encounter a long walk through desert and then they have to cross a mountain range before they find any people.

• Birds that steal food from the mouths of other birds are called kleptoparasitic birds.

• There's something called a Prickly Redfish that looks like a huge lumpy carpet. It's actually a kind of sea cucumber, and it crawls across the seafloor on its orange tube feet. It's considered a delicacy in East Asian cuisine.

(Photo from the Australian Government Reef Monitoring program)

• The fur of the sea otter is the densest of any mammal on the planet. Because its fur is so dense, the sea otter's skin never gets wet, even though it spends its entire life in the water.
  

• Sometimes old coral reefs get so sculpted by the ebb and flow of tidal waters that they get carved away on the sides and underneath until they stand up out of the water like tables, or mushrooms. These are called champignons, which is French for mushrooms.

Champignon in a lagoon, I think in the Indian Ocean
(Photo by Donald & Esther)


The carving action of the water is more dramatic on this champignon.
(Photo by Ben Stobart, Aldabra Marine Programme)

• Most marine mammals (sea lions, seals, penguins, walruses, etc.) are completely carnivorous. No vegetarians there.

• There's a sinkhole off the coast of Belize called the Great Blue Hole. It's a 480-foot hole in the limestone reef and because of its depth, the water has a brilliant blue color. People do go diving there, but it's treacherous because of the stalactites hanging down from the walls and the fact that sharks like to hang out in it.

The Great Blue Hole. Not kidding about the blue.
(Photo from Biocassanova's blog)

• The Cookiecutter shark has lips that hold its victim in place and then its teeth bites cookie-shaped chunks from its prey.

• Juvenile zebra sharks have stripes. Adult zebra sharks have spots.

• Polar ice can be different colors. If it's white, it has a lot of air bubbles trapped in it. Older ice that's had most of the air bubbles compressed out of it is blue. Sometimes an iceberg can flip over, in which case the algae growing on the bottom becomes visible, and the ice appears to be green.

• You've probably heard of the fjords in Norway. But did you also know that there are fjords in Chile? That's what the Andes mountains descend into on the southwest coast of Chile. There are 21,500 square miles of fjords down there.

These people have gotten off the M/V Mare Australis cruiseliner and are taking the optional trek on the ice fjords on the Chilean coast. Note the blue ice!
(Photo from Explore UK, which has more information about this cruise)

• The vampire squid is bioluminescent (glows) and it has things called photophores on the tips of its arms. When a predator tries to get it, the vampire squid thrashes its arms and releases sparkles of light all over the place into the water. The flashing lights distract the predator and by the time the sparkles have died out, the squid has escaped.

• A polar bear's paw may be over 12 inches wide.

I'm telling you, this book is magnificent. Oh, I forgot to mention: I got it for $6.50 from my local Border's.

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