THE WORLD'S LARGEST CALDERAS - Calderas are large craters formed by volcanic explosions or by unsupported surface rock collapsing into empty magma chambers beneath the ground. They sometimes are referred to as supervolcanoes. One way to understand calderas is to think of them as reverse volcanoes. Volcanic eruptions often will be the cause of magma chambers being left empty and leaving the volcano above unsupported. This can cause the ground above, sometimes an entire volcano, to collapse into the empty chamber. Yellowstone Park is perhaps the most well-known caldera in the United States, drawing millions of tourists every year. According to Yellowstone's website, the supervolcano was the site of massive eruptions 2.1 million years ago, 1.2 million years ago, and 640,000 years ago. Those eruptions were, respectively, 6,000 times, 70 times, and 2,500 times more powerful than the 1980 eruption of Mount St. Helens in Washington. What today is known as Lake Toba in Indonesia is the result of perhaps the greatest volcanic eruption since the dawn of early man. Approximately 74,000 years ago, Mount Toba's eruption produced about 2,500 times more volcanic ash than Mount St. Helens. This led to a volcanic winter that had a devastating effect on the entire human population of the time. The volcanic winter lasted six years and led to a 1,000-year-long ice age, according to research, and the world population was reduced to about 10,000 adults. Research into how a massive eruption would impact the world day shows the effects to be potentially devastating.

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The World's Largest Calderas

These Are the World's Largest Calderas

By Andrew Alden

Calderas are large craters formed by volcanic explosions or by unsupported surface rock collapsing into empty magma chambers beneath the ground.

They sometimes are referred to as supervolcanoes.

One way to understand calderas is to think of them as reverse volcanoes.

Volcanic eruptions often will be the cause of magma chambers being left empty and leaving the volcano above unsupported.

This can cause the ground above, sometimes an entire volcano, to collapse into the empty chamber.

Yellowstone Park

Yellowstone Park is perhaps the most well-known caldera in the United States, drawing millions of tourists every year.

According to Yellowstone's website, the supervolcano was the site of massive eruptions 2.1 million years ago, 1.2 million years ago, and 640,000 years ago.

Those eruptions were, respectively, 6,000 times, 70 times, and 2,500 times more powerful than the 1980 eruption of Mount St. Helens in Washington.

Explosive Force

What today is known as Lake Toba in Indonesia is the result of perhaps the greatest volcanic eruption since the dawn of early man.

Approximately 74,000 years ago, Mount Toba's eruption produced about 2,500 times more volcanic ash than Mount St. Helens. This led to a volcanic winter that had a devastating effect on the entire human population of the time.

The volcanic winter lasted six years and led to a 1,000-year-long ice age, according to research, and the world population was reduced to about 10,000 adults.

Potential Modern Impact

Research into how a massive eruption would impact the world day shows the effects to be potentially devastating. 

One study focusing on Yellowstone suggests another eruption comparable in size to the three biggest ones of the past 2.1 million years would kill 87,000 people instantly. The volume of ash would be enough to collapse rooftops in states surrounding the park.

Everything within about 60 miles would be destroyed, most of the western United States would be covered in about 4 feet of ash, and an ash cloud would spread across the entire planet, casting it in shadow for days.

The impact on vegetation could lead to food shortages across the planet.

Visiting the Largest Calderas on the Planet

Yellowstone is just one of many calderas throughout the world. Like Yellowstone, many of the others can be interesting and fascinating places to visit and to study.

Below is a list of the world's largest calderas:

Caldera name	Country	Location	Size (km)	Most recent eruption
La Pacana	Chile	23.10 S 67.25 W	60 x 35	Pliocene
Pastos Grandes	Bolivia	21.45 S 67.51 W	50 x 40	8.3 Ma
Kari Kari	Bolivia	19.43 S 65.38 W	30	Unknown
Cerro Galan	Argentina	25.57 S 65.57 W	32	2.5 Ma
Awasa	Ethiopia	7.18 N 38.48 E	40 x 30	Unknown
Toba	Indonesia	2.60 N 98.80 E	100 x 35	74 ka
Tondano	Indonesia	1.25 N 124.85 E	30 x 20	Quaternary
Maroa/ Whakamaru	New Zealand	38.55 S 176.05 E	40 x 30	500 ka
Taupo	New Zealand	38.78 S 176.12 E	35	1,800 yr
Yellowstone	USA-WY	44.58 N 110.53 W	85 x 45	630 ka
La Garita	USA-CO	37.85 N 106.93 W	75 x 35	27.8 Ma
Emory	USA-NM	32.8 N 107.7 W	55 x 25	33 Ma
Bursum	USA-NM	33.3 N 108.5 W	40 x 30	28-29 Ma
Longridge (McDermitt)	USA-OR	42.0 N 117.7 W	33	~16 Ma
Socorro	USA-NM	33.96 N 107.10 W	35 x 25	33 Ma
Timber Mountain	USA-NV	37 N 116.5 W	30 x 25	11.6 Ma
Chinati Mountains	USA-TX	29.9 N 104.5 W	30 x 20	32-33 Ma
Long Valley	USA-CA	37.70 N 118.87 W	32 x 17	50 ka
greater Maly Semiachik/Pirog	Russia	54.11 N 159.65 E	50	~50 ka
greater Bolshoi Semiachik	Russia	54.5 N 160.00 E	48 x 40	~50 ka
greater Ichinsky	Russia	55.7 N 157.75 E	44 x 40	~50 ka
greater Pauzhetka	Russia	51 N 157 E	~40	300 ka
greater Ksudach	Russia	51.8 N 157.54 E	~35	~50 ka

Andrew Alden

Geology Expert

Education

B.A., Earth Sciences, University of New Hampshire

Introduction

Professional geologist, writer, photographer, and geological tour guide

Thirty-seven years of experience writing about geological subjects

Six years as a research guide with U.S. Geological Survey (USGS)

Member of Geological Society of America (GSA), and American Geophysical Union (AGU)

Experience

Andrew Alden is a former writer for ThoughtCo who contributed hundreds of articles for more than 17 years. Andrew works as a geologist, writer, editor, and photographer. He has written on geological subjects since 1981 and participates actively in his field. For example, Andrew spent six years as a research guide with the U.S. Geological Survey, leading excursions on both land land and at sea. And since 1992, he has hosted the earthquakes conference for the online discussion platform, The Well, which began as a dialogue between the writers and readers of the Whole Earth Review. 

In addition, Andrew is a longtime member of the member of the Geological Society of America — an international society that serves members in academia, government, and industry; and the American Geophysical Union — a community of earth and space scientists that advances the power of science to ensure a sustainable future.

Andrew lives in Oakland, California; and though he writes about the whole planet and beyond, Andrew finds his own city full of interest too and blogs about its geology. 

Education

Andrew Alden holds a bachelor's (B.A.) degree in Earth Science from the University of New Hampshire, College of Engineering and Physical Sciences, in Durham, N.H.

Awards and Publications

Andrew Alden on Earthquakes ​(The Well Group, Inc., 2011)

Assessment of River — Floodplain Aquifer Interactions (Environmental and Engineering Geoscience, 1997)

Andrew Alden on Hosting (The Well Group, Inc., 1995)

ThoughtCo and Dotdash

ThoughtCo is a premier reference site focusing on expert-created education content. We are one of the top-10 information sites in the world as rated by comScore, a leading Internet measurement company. Every month, more than 13 million readers seek answers to their questions on ThoughtCo.

For more than 20 years, Dotdash brands have been helping people find answers, solve problems, and get inspired. We are one of the top-20 largest content publishers on the Internet according to comScore, and reach more than 30% of the U.S. population monthly. Our brands collectively have won more than 20 industry awards in the last year alone, and recently Dotdash was named Publisher of the Year by Digiday, a leading industry publication.

https://www.thoughtco.com/worlds-largest-calderas-4090141

PLAYING WITH (ST. ELMO'S) FIRE - When St. Elmo made an appearance, we could sometimes reach out to the front windshield and create what looked like miniature lightning bolts between the tips of our fingers and the windshields and then "play" with them — moving them around by manipulating our fingers (kind of like those spark-filled globes you see at children's science museums) - the sensation was something like what you feel when an extremity has gone to sleep and tingles as it wakes up again - it didn't feel like a shock, but just kind of tickled - This phenomenon is an extremely rare electrical/chemical occurrence and associated with thunderstorms, although what causes it and what it actually is remains somewhat of a mystery. Reports that describe this occurrence have placed it in a variety of locations, such as wandering through rooms in a house or, as this questioner identifies, shooting down the aisle of an airplane. The cause of this mysterious and intriguing glowing sphere puts out the approximate lighting of a 100-watt bulb and generally occurs during stormy weather. Its average lifetime seems to be around 10 seconds after which it either just fades away or sometimes ends more dramatically, dissipating with a small "explosion." When it appears inside a glass tube, we know it as a neon sign. When it occurs in nature, we call it "St. Elmo's Fire." It's a continuous electric spark and lasts anywhere from a second or two to several minutes at a time.

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Playing with (St. Elmo's) fire

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When St. Elmo made an appearance, we could sometimes reach out to the front windshield and create what looked like miniature lightning bolts between the tips of our fingers and the windshields and then "play" with them — moving them around by manipulating our fingers (kind of like those spark-filled globes you see at children's science museums) - the sensation was something like what you feel when an extremity has gone to sleep and tingles as it wakes up again - it didn't feel like a shock, but just kind of tickled

Meryl Getline

Ask the Captain

Is there something you want to know about air travel? Send Captain Meryl Getline an e-mail, and she may publish it in an upcoming column. By e-mailing her (include your name and town), you are agreeing to have your question shared.

Question: My husband was on a night flight years ago where he swears a "fireball" streaked down the aisle. No one was hurt, no damage was done and thankfully it didn't scare the majority of passengers, as most were asleep. We don't think this could have been lightning, as I imagine the static wicks on the wings would dissipate that, but can static electricity build up inside a plane causing something like this? — Linda Kelly, Arlington, Va.

Answer: What your husband has described is a phenomenon known as "ball lightning."

I've heard it described by several flight attendants and a few passengers over the years as a glowing "ball of fire that went zooming down the aisle" but never witnessed it myself.

It is thought that this phenomenon is an extremely rare electrical/chemical occurrence and associated with thunderstorms, although what causes it and what it actually is remains somewhat of a mystery.

Reports that describe this occurrence have placed it in a variety of locations, such as wandering through rooms in a house or, as this questioner identifies, shooting down the aisle of an airplane.

There is a mention of it in Laura Ingall Wilder's On the Banks of Plum Creek (the fourth book of the Little House series) where it appeared near a stovepipe, then rolled across the floor.

When I first heard the description of what I later discovered was called "ball lightning," frankly I dismissed it as the product of people's overactive imaginations, but I've had several readers say they've witnessed it and so I decided to do some research.

A simple online search of the words "ball lightning" yielded a surprising number of eyewitness accounts, and even some sites documenting scientific attempts to create this glowing sphere.

Although apparently scientists no longer treat it as a myth, they're not able to explain it fully.

Some statistics say that as much as 5% of the population has witnessed the phenomenon known as ball lightning.

So, what is it? Apparently, there are lots of theories, but nobody seems to know for sure.

Some have described ball lightning as glowing balls of plasma.

Others describe it as "St. Elmo's Fire" that "got loose." (See the next question and answer for an explanation of St. Elmo's Fire.)

In any case, the cause of this mysterious and intriguing glowing sphere puts out the approximate lighting of a 100-watt bulb and generally occurs during stormy weather.

Its average lifetime seems to be around 10 seconds after which it either just fades away or sometimes ends more dramatically, dissipating with a small "explosion."

Question: What can you tell us about St. Elmo's Fire? Have you ever experienced it? What is it? What makes it happen? Is it the same as lightning? — Jim Colby, Fosters, Ala.

I'll assume you mean a phenomenon of nature and not the cheesy 1980's movie.

St. Elmo's Fire has been described as a "glow discharge" and is not the same as lightning.

When it appears inside a glass tube, we know it as a neon sign.

When it occurs in nature, we call it "St. Elmo's Fire."

It's a continuous electric spark and I've seen it last anywhere from a second or two to several minutes at a time.

When we fly through clouds, often St. Elmo's Fire will appear on our front windshields as a glowing blue light which at first frames our window, then moves more and more toward the center as a bluish-green light.

If you're ever looking out a passenger window at the same time, we can see it on our front windshields, you might be able to see it illuminating our wingtips.

Others have spotted it around church steeples and the masts of ships (St. Elmo is known as the patron saint of sailors).

It's even referred to by Shakespeare in The Tempest. In researching this column, I found that most sightings were on the wingtips of airplanes and on churches.

I've witnessed St. Elmo's Fire dozens of times as a pilot, but I've never seen it anywhere else.

Sometimes St. Elmo's Fire has been confused with "ball lightning," and although there doesn't seem to be any real agreement among scientists on what ball lightning actually is, there is agreement that they are not one and the same.

St. Elmo's Fire is always attached to something whereas ball lightning is free-floating.

When I used to fly unpressurized light twin-engine aircraft, St. Elmo's Fire was a somewhat regular occurrence on cloudy days.

Because we were not able to fly very high without pressurization, we often flew through clouds instead of being able to top them.

When St. Elmo made an appearance, we could sometimes reach out to the front windshield and create what looked like miniature lightning bolts between the tips of our fingers and the windshields and then "play" with them — moving them around by manipulating our fingers (kind of like those spark-filled globes you see at children's science museums).

The sensation was something like what you feel when an extremity has gone to sleep and tingles as it wakes up again. It didn't feel like a shock, but just kind of tickled.

This manipulation doesn't work nearly as well on the aircraft I fly now with their heavy windshields, but we still see St. Elmo once in a while when we're in a high cloud layer.

The last visit by St. Elmo to my own cockpit was about three months ago, over the East China Sea between Tokyo and Taipei.

Meryl Getline is a pilot, author of the award-winning book The World at My Feet and a keynote speaker for corporate and other gatherings. She also publishes her own websites, fromthecockpit.com and flyingfearless.com. All opinions expressed in this column are exclusively those of Capt. Meryl Getline. If you have a question, send it to her at travel@usatoday.com, acknowledging she may use it in a future column.

https://usatoday30.usatoday.com/travel/columnist/getline/2005-10-17-ask-the-captain_x.htm