Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week's contribution is from is from Mike Poland, geophysicist with the U.S. Geological Survey and scientist-in-charge of the Yellowstone Volcano Observatory.
I have a confession to make. I really don't like the term supervolcano. And I'd like to use this week's edition of Yellowstone Caldera Chronicles to rant about the topic. I'd also like to propose that we use a different term.
The first known use of supervolcano is actually from the mid-1900s. In 1925, geologist Edwin Hodge proposed that the Three Sisters volcanic region of central Oregon was actually the site of one very large volcano, which he called Mt. Multnomah. This idea was later disproven by geologist Howell Williams (the same scientist who deciphered the geologic history of Crater Lake in Oregon), and a review of Williams' 1948 book on Oregon volcanoes referred to Hodge's Three Sisters hypothesis as a supervolcano.
The term lay dormant (pun intended) for decades, and was mostly absent from the scientific literature until the 2000s. The term "super eruption" had been used, however, to describe some of the largest known eruptions on Earth, like that of Toba, Indonesia, 74,000 years ago.
By the early 2000s, supervolcano started creeping into scientific articles. More general and widespread use of the term exploded (so to speak) following the 2005 release of the British-Canadian docudrama "Supervolcano," a disaster television film that centered around a hypothetical large eruption of Yellowstone.
Ever since, use of "supervolcano" has, ahem, blown up. (OK, OK, I'll stop with the volcano puns now.)
It seems innocent — is there really a downside to the term? After all, it does conjure an eruption of incredible size, which is something that modern humans have (fortunately) never witnessed. But it also oversimplifies the process and causes misunderstanding.
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I have three main reasons for disliking the term.
First, it's trite. Remember back in the 2000s when people used uber in front of a word to mean "very"? The pizza wasn't just delicious, it was uber-delicious. The summer wasn't hot, it was uber-hot. It was so uber-annoying! Fortunately, the fad faded. The same can be said for supervolcano. Adding super boils a complex and important aspect of volcanology down into something that sounds like a catch phrase. Ay carumba!
Second, it's misleading. Calling something a supervolcano makes it sound like a volcano that only has massive eruptions. Of course, this is not true. Most Yellowstone eruptions that involve magma reaching the surface are lava flows. In fact, there have been about 80 lava flows of varying compositions in and around Yellowstone since the last time the system experienced a catastrophic explosion. Yellowstone is a lot more than just explosions, and calling it a supervolcano is a gross oversimplification.
Third, it's misapplied. Volcanologists have come to refer to super eruptions as those that have generated 1000 km3 of ash and other volcanic products. This is equivalent to an "8" on the Volcano Explosivity Index scale, which is sort of like a Richter scale for volcanic eruptions. That means a VEI=8 eruption generated 10 times more material than a VEI=7 eruption, and 100 times more than a VEI=6 eruption. For reference, the 1980 Mount St. Helens eruption was VEI=5. The 1991 eruption of Pinatubo, Philippines, was VEI=6. So a VEI=8 is truly epic. Why is it, then, that volcanoes that have never had VEI=8 eruptions are called supervolcanoes? For example, the largest eruption of Campi Flegrei, Italy, occurred about 39,000 years ago and was VEI=7. Yet Campi Flegrei is also often called a supervolcano. Is it a supervolcano if it has never had a super eruption?
My wise colleague, Jamie Farrell, assistant research professor at the University of Utah and chief seismologist of the Yellowstone Volcano Observatory, likes to say that "there are no supervolcanoes, only volcanoes that have super eruptions." I couldn't agree more.
So I have a suggestion. Let's ditch the overused, misrepresentative, and misapplied supervolcano term. Instead, let's call them caldera systems. This would refer to any volcano that has experienced an explosion massive enough that the surface has collapsed into a partially emptied magma chamber. Campi Flegrei, Crater Lake (Oregon), and Yellowstone would all qualify. And if you must use the word super, use it when referencing specific eruptions — like the massive explosion from Yellowstone 631,000 years ago. That was a VEI=8 super eruption that occurred from a caldera system. See? Doesn't that sound better?
Okay, rant over. Have a super day!