Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.
Showing posts with label dangerous volcanoes. Show all posts
Showing posts with label dangerous volcanoes. Show all posts

Tuesday, May 6, 2025

The pressure cooker

It will come as no surprise to regular readers of Skeptophilia that I have a peculiar fascination for things that are huge and powerful and can kill you.

I'm not entirely sure where this obsession comes from, but it's what's driven me to write here about such upbeat topics as giant predatory dinosaurs, tornadoes, hurricanes, massive earthquakes, supernovas, gamma-ray bursters, and the cheerful concept of "false vacuum decay" (which wouldn't just destroy the Earth, but the entire universe).  I'm guessing part of it is my generally anxiety-ridden attitude toward everything; after all, just because we don't think there's a Wolf-Rayet star nearby that's ready to explode and fry the Solar System doesn't mean there isn't one.  I know that worrying about all of that stuff isn't going to (1) make it any less likely that it'll happen, or (2) make a damn bit of difference to my survival if it does, but even so I don't seem to be able to just relax and focus on more positive things, such as the fact that with the sea-level rise predicted from climate change, it looks like here in upstate New York I may finally own ocean-front property.

It's also why I keep regular tabs on the known volcanoes on the Earth -- on some level, I'm always waiting for the next major eruption.  One of the potentially most dangerous volcanoes on Earth is in Italy, and I'm not talking about Vesuvius; I'm referring to the Campi Flegrei ("burning fields," from the Greek φλέγω, "to burn"), which isn't far away from the more famous mountain and seems to be powered by the same magma chamber complex that obliterated Pompeii, Herculaneum, and Stabiae in 79 C.E.  Both Vesuvius and the Campi Flegrei are highly active, and near the top of the list of "world's most dangerous volcanoes."

The problem is, the three million residents of Naples live right smack in between the two, only twenty-odd kilometers away from Vesuvius (to the east) and Campi Flegrei (to the west).  (For reference, Pompeii was nine kilometers from the summit of Vesuvius.)

The Campi Flegrei, looking west from Naples [Image licensed under the Creative Commons Baku, VedutaEremo2, CC BY-SA 4.0]

The problem is that volcanoes like these two don't erupt like the familiar fountains of lava you see from Kilauea on the Big Island of Hawaii, and the recent eruption on La Palma in the Canary Islands and the one near Grindavík in Iceland.  The most typical eruption from volcanoes like Vesuvius and Campi Flegrei are pyroclastic flows -- surely one of the most terrifying phenomena on Earth -- a superheated mass of steam and ash that rush downhill at speeds of up to a hundred kilometers an hour, flash-frying everything in its wake.  That the Campi Flegrei volcanoes are capable of such massive events is witnessed by the surrounding rock formation called the "Neapolitan Yellow Tuff."  A "welded tuff" is a layer of volcanic ash that was so hot when it stopped moving that it was still partially molten, and fused together into a solid porous rock.

A video of a pyroclastic flow from Mount Unzen in Japan in 1991

The Neapolitan Yellow Tuff isn't very recent; it came from an eruption about 39,000 years ago.  But there are signs the Campi Flegrei are heating up again, which is seriously bad news not only for Naples but for the town of Pozzuoli, which was built right inside the main caldera.  The residents of Pozzuoli have had to get used to regular rises and falls of the ground, some by as much as an alarming two meters.  In fact, between 1982 and 1984, there was so much uplift -- followed by magnitude-4 earthquakes and thousands of microquakes -- that the harbor became too shallow for most ships to dock, and the entire population of forty thousand was evacuated until things seemed to simmer down.

In fact, the reason the topic comes up is a study out of Stanford University and the University of Naples that appeared this week in the journal Science Advances, that found this terrifying swell-and-subside isn't due primarily to magmatic movement, as was feared -- it's the bubbling of superheated groundwater.  The study looked at the composition of the "caprock," the rock layer on top of the formation, and found that when mixed with hot water it forms something like a natural fibrous cement.  This then plugs up cracks and prevents groundwater from escaping.

The whole thing is like living on the lid of a giant pressure cooker.

Of course, unlike (I hope) your pressure cooker, the rock doesn't have the tensile strength to manage the pressure fluctuations, so ultimately it breaks somewhere, triggering an earthquake and steam eruptions, after which the caprock settles back down for a while until the cracks all reseal and the pressure starts to rebuild.

This is all pretty scary, but it does point scientists in a direction of how to mitigate its potential for harm.  "I call it a perfect storm of geology -- you have all the ingredients to have the storm: the burner of the system -- the molten magma, the fuel in the geothermal reservoir, and the lid," said Tiziana Vanorio, who co-authored the study.  "We can't act on the burner but we do have the power to manage the fuel.  By restoring water channels, monitoring groundwater, and managing reservoir pressure, we can shift Earth sciences toward a more proactive approach -- like preventive health care -- to detect risks early and prevent unrest before it unfolds.  That's how science serves society."

Which is all very well, but I still wouldn't want to live there.  I visited Italy last year and loved it, but the area around Naples -- that'd be a big nope for me.  When we were in Sicily, itself no stranger to seismic unrest, one of our tour guides said, "We might be taking a risk living here, I suppose.  But those people up in Naples -- they're crazy."

That anyone would build a town on top of an active volcano is explained mostly by the fact that humans have short memories.  And also, the richness of volcanic soils is generally good for agriculture.  Once Pompeii was re-discovered in the middle of the eighteenth century, along with extremely eerie casts of the bodies of people and animals who got hit by the pyroclastic flow, you'd think people would join our Sicilian tour guide in saying, "no fucking way am I living anywhere near that mountain."  But... no.  If you'll look at a world map, you might come to the conclusion that siting big cities near places prone to various natural disasters was some kind of species-wide game of chicken or something.

Not a game I want to play.  Such phenomena make me feel very, very tiny.  I'm very thankful that I live in a relatively peaceful, catastrophe-free part of the world.  Our biggest concern around here is snow, and even that's rarely a big deal; we don't get anything like the killer blizzards that bury the upper Midwest and Rocky Mountain states every year.  Given my generally neurotic outlook on life, I can't imagine what I'd be like if I did live somewhere that had serious natural disasters.

Never leave my underground bunker, is probably pretty close to the mark.

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Monday, November 8, 2021

Prelude to a detonation

Even though in general I don't think synchronicity Means Anything, there's no doubt that it can be pretty peculiar.

For example, it seems like in the last few days the universe has tried to get me to think about volcanoes.  First, Scientific American recently featured in their "New Books" column Robin George Andrews's Super Volcanoes, and given my fascination with volcanoes in general I had to get it (and it impressed me enough that it's this week's book-of-the-week).  Andrews's book goes a long way toward dispelling a lot of the hype around places like Yellowstone (no, it's not on the verge of an eruption), and has a lot of cool interviews with volcanologists, much in the style of the wonderful essayist John McPhee.  Only a couple of days after I started reading it, a friend sent me a link to the Naked Science YouTube video "Supervolcanoes," which seemed to be the anti-Andrews; if I can sum it up, it would be "WE'RE ALL FUCKED RUN FOR YOUR LIFE."  It isn't terrible, and does include some actual science, but the most striking thing about it is a CGI rendition of Yellowstone blowing sky-high which they use over and over and over and over in the fifty-minute-long video, as if they'd paid somebody a hefty sum to do the rendering, and by god, they were gonna get their money's worth out of it.

Then, just yesterday, a (different) friend sent me a link to a paper in Proceedings of the National Academy of Sciences that kind of splits the difference between Naked Science's screaming alarmism and Andrews's breeziness; it looks at the scarily huge Mount Toba volcano in Indonesia, and comes to the unsettling conclusions that (1) it definitely will erupt again, and (2) we probably won't have much warning when it does.

The last significant eruption of Toba was about 74,000 years ago, and was a VEI8 -- the highest ranking on the Volcanic Explosivity Index -- releasing an estimated three thousand cubic kilometers of ash and lava, and causing a worldwide (if temporary) drop in average temperature by about three degrees Celsius.  (For comparison, this is over seven hundred times the volume ejected by the May 1980 eruption of Mount St. Helens.)  The eruption blew the entire top of the mountain clean off, and the evacuation of the magma chamber beneath it caused the caldera to collapse.  It filled with water, and is now a beautiful -- and seemingly peaceful -- crater lake, Lake Toba.

[Image licensed under the Creative Commons Visions of Domino, Indonesia - Lake Toba (26224127503), CC BY 2.0]

The operative word here is "seemingly."  The processes that caused the original eruption, mostly the subduction of the Indian and Australian Tectonic Plates beneath the Sunda Plate, continue to cause massive earthquakes including the colossal (9.2 on the Richter Scale) Sumatra-Andaman Earthquake of December 2004, which killed over 225,000 people.  In the case of Toba, the magma chamber has been steadily refilling, and now contains an estimated 50,000 cubic kilometers of magma -- four times the volume of Lake Superior.  This refilling has pushed the entire caldera upward, lifting Samosir Island and the Uluan Peninsula an estimated 450 meters.

It's hard to talk about this without lapsing into superlatives.  The scariest thing about it, though, is that the recent study indicates that such volcanoes can seem quiescent until -- well, until they aren't any more.  "[W]ith few super-eruptions in the last two million years, it is not possible for us to obtain statistically significant values for the frequency of these catastrophic events at a global scale," said study co-author Ping-Ping Liu of Peking University, in a press release from the Université de Genève.  "Our study also shows that no extreme events occur before a super-eruption.  This suggests that signs of an impending super-eruption, such as a significant increase in earthquakes or rapid ground uplift, might not be as obvious as pictured in disaster movies by the film industry.  At Toba volcano, everything is happening silently underground."

The reassuring part is "not as obvious" doesn't mean "without any warning;" the entire Indonesian archipelago is an area of intense study by volcanologists and seismologists, and it's likely there'd be enough anomalous activity to give us at least a hint that an eruption was impending.  Whether we'd do much about it in the form of evacuations is another matter.  Sumatra (where the volcano is located) and the nearby island of Bali are densely populated, and the idea of getting all those people out (to where?) makes the phrase "mammoth undertaking" a significant understatement.  And for those of you who like certainty, the current study doesn't give us any clear idea of exactly when the next big eruption will occur, just that (1) it's inevitable, (2) when it does, it'll be bad, (3) the filling of the magma chamber is still happening, and (4) there are signs that the volcanic activity at Toba and the surrounding regions is speeding up.

"[There's been a] progressive increase of the temperature of the continental crust in which Toba’s magma reservoir is assembled," Liu said.  "The input of magma has gradually heated the surrounding continental crust, which makes the magma cool slower.  This is a ‘vicious circle’ of eruptions: the more the magma heats the crust, the slower the magma cools and the faster the rate of magma accumulation becomes.  The result is that super-eruptions can become more frequent in time."

So there's your cheerful news of the day.  As far as the synchronicity aspect of this, I'm not gonna make much of it.  The fact that two different friends know enough of my obsession with volcanoes and earthquakes to send me the link to the YouTube video and paper is hardly to be wondered at.  As far as the book review, it's no wonder I noticed it given that the tile of the book is Super Volcanoes.  I don't think this is some kind of cosmic warning that we're about to get blown to smithereens.

So if you were looking for an excuse to stay home from work this week, you'll probably have to come up with a different one.

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If Monday's post, about the apparent unpredictability of the eruption of the Earth's volcanoes, freaked you out, you should read Robin George Andrews's wonderful new book Super Volcanoes: What They Reveal About the Earth and the Worlds Beyond.

Andrews, a science journalist and trained volcanologist, went all over the world interviewing researchers on the cutting edge of the science of volcanoes -- including those that occur not only here on Earth, but on the Moon, Mars, Venus, and elsewhere.  The book is fascinating enough just from the human aspect of the personalities involved in doing primary research, but looks at a topic it's hard to imagine anyone not being curious about; the restless nature of geology that has generated such catastrophic events as the Yellowstone Supereruptions.

Andrews does a great job not only demystifying what's going on inside volcanoes and faults, but informing us how little we know (especially in the sections on the Moon and Mars, which have extinct volcanoes scientists have yet to completely explain).  Along the way we get the message, "Will all you people just calm down a little?", particularly aimed at the purveyors of hype who have for years made wild claims about the likelihood of an eruption at Yellowstone occurring soon (turns out it's very low) and the chances of a supereruption somewhere causing massive climate change and wiping out humanity (not coincidentally, also very low).

Volcanoes, Andrews says, are awesome, powerful, and fascinating, but if you have a modicum of good sense, nothing to fret about.  And his book is a brilliant look at the natural process that created a great deal of the geology of the Earth and our neighbor planets -- plate tectonics.  If you are interested in geology or just like a wonderful and engrossing book, you should put Super Volcanoes on your to-read list.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]