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Pyroclastic flows: The secret of their deadly speed
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- Published on Feb 16, 2026
- When a volcano erupts, pyroclastic flows are often the biggest danger to anyone nearby. These fast-flowing currents of rock, ash and extremely hot gas are extremely difficult to study, so researchers in New Zealand created their own. By closely studying pyroclastic flows in their specially-made lab, they identified a very thin layer of gas that helps explain how this volcanic phenomenon moves so fast and can travel so far.
Read the research paper: www.nature.com...
8th April 2019
Rittmann has 60 years ago a clear description of the mechanism of pyroclastic flows made:In a gas rich and tough magma with falling pressure the gas bubbles grow til they are confluenting, their walls break to glass splinters an a most movable emulsion of hot fragments in hot gas escapes with high speed.
That makes so much sense. A man saw a pyroclastic blast barreling towards him when he was in the woods. He very quickly found a shallow area and laid there until it passed, and lived to talk about it. It now makes sense how he wasn't killed by debris.
You forget the heat
The gas acts as a lubricant not a bridge. This man was caught in a cooled down pyroclastic surge
@SirKolass I'm super confused right now.... The comment I made was not for this video. It was originally about the camera men that died in the Mount St. Helens eruption, but a hiker lived because he hid in a ditch.... Either that, or I'm going crazy lol.
@arrowed_sparrow1506 you might be thinking of the dude who jumped in a river or ditch trying to escape the fatal front of a wildfire and was the only one in his party to survive. He documented the immediate aftermath.
@arrowed_sparrow1506 ooooh wait, I think I know what you're talking about. He was with his wife or something. Yea it had cooled off significantly by the time it reached them several miles further.
I have seen this phenomena my self first hand, and i can tell, its all but fun.
With that being said, it was not from a volcano, but rather a at a power plant, dealing with fly ashes.
When disposal of fly ashes, under right circumstances, ash will behave just as described, as a fluid, and its fast, super fast, there is no time to react, if it wasn't because we had the right protecting gear, i wouldn't be writing this-
And that was "cold" fly ash, pyroclastic flows is super hot at the same time as its insanely fast.
Creates a pyroclastic flow 10 feet away.
👀 Wears a t shirt
You'd think that scientist operating his lab pyroclastic flow might want to put on a dust mask ...
Yeah whoops lol
@tornadoclips2022. strange seeing you here
Remarkable discovery.
I don't mean to be dismissive, but when I took Basic Volcanology in college in 1996, they mentioned that it was clear pyroclastic flows ran on fluidized layers of superheated gas that had separated out from the column as it descended.
I'm not really sure what the researchers did here except document a phenomenon that was already widely predicted. They "discovered" nothing.
Dante's Peak is the most accurate volcano film, change my mind.
Holy ducking shizzle dude! I’m 3 minutes into Dante’s peak but I paused it and googled pyroplastic material because I know where it comes from but wondered what it was and I came here to see your top comment about Dante’s peak tripped me out! Think I’m syncing with the universe, today I watched a vid with floyd mayweather jr in 1996 and I just so happen to glance at the clock in the bottom right corner and it was - Round 1 - 1:11 ...been happening a lot recently.. anyways have a good day!
What about supervolcano (based on a theoretical Yellowstone worst case scenario)? It was mostly pretty damn good (some pyroclastic flow scenes were iffy and the government was way to cooperative) and very realistic including a mini ice age in the post-yellowstone eruption era.
@K Tipnis hahaha that’s what I meant
@molvolgia I watched this video right after watching Dante's peak too lmao
I work at Mt St Helens and we watch Dante’s Peak for a good laugh.
It's so cool how it moves like water.
Would be interesting to see if one could do something to disrupt the boundary layer and slow/stop the flow earlier. Don't know much about fluid dynamics, but I think boundary layer adhesion is pretty well understood?
You’d imagine the forest would do a good job really but guess not
@sir.benzerlot4571sort of does but it takes miles of it.
This helps my child with her homework
cool
Bummer. My mon never let me recreate pyroclastic flow at home. Your kid is one luck bastard.
Glad to know Annie
Whereas Water follows the path of least resistance, Hot Gas travels to areas where pressure does not exist.
I wonder if this so-called volcano in the lab could be good for those who want to make a disaster film based around a volcanic eruption?
No...3d fx would be way cheaper to do
Amazing video. Great research. Letting the flow out the front door was the funniest bit... at least until I saw the research was published by Lube et al.
St Vincent and the Grenadines La Soufriere is still erupting at the moment, my homeland is filled with plume ash.🇻🇨
Great video. Short and to the point. A+
That bottom layer might be some kind of Leidenfrost-effect?
Stein-Erik Dahle wtf
Well, if that is the case, could it be because of moisture present in the soil?
No, the tank was dry.
More like the ground effect
"No one knows how it moves" proceeds to explain exactly how it moves
The phenomenon happens with very fine, very dry soil on a slope and in a snow avalanche. Moving gases within keep it fluid, like water does in quicksand.
Also makes sense when you consider all of the gases in a pyroclastic flow were both under pressure and extremely heated when released, and now in atmosphere those gasses are doing what superheated, pressurized gasses do in any EXPLOSION, rapidly expanding in volume as they move. The gasses are not only rolling downhill from gravity due to being denser than air, but they're also rapidly expanding at the same time and accelerating anything along for the ride.
They'd certainly be causing any air they come into contact with to expand, but wouldn't the volcanic gasses be fully expanded and slowly cooling once they've left the earth and become part of the flow? (I'm assuming they wouldn't be getting further heated by the ash since it all came from the same place)
Unless it's just taking a long long time to finish expanding after coming out of the ground where it was under more pressure, and that is occurring throughout much of the flow?
@ChadDidNothingWrong Air gets mixed in, gets heated, and expands. Not sure if there could still be some pressurized gas bubbles.
Of course, the topic as a whole is more complicated than can be fully covered in a 2-minute video.
@dragonridley forgot about the air mixing in...lol. Thank you for the response
Now that why the move like a monster chasing you
This very interesting.
Fascinating. Thank you.
Interesting that is sort of like a Leidenfrost effect
Soundtrack: Demolition Hammer - Pyroclastic Annihilation
Insight gained, thanks.
I love Philomena Cunk's voice.
It all makes sense now
1:58 he really said BAI FELICIA
Holy Smoke. Volcanoes invent the hover craft before Marty McFly did.
Perfect video
Anyone here after that Rings of Power episode? A ton of comments were talking about pyroclastic flow and I admit I had no idea what that was until now lol
Wow, remarkable. Solves a lot of mysteries.
I am still having a question: what about COLD landslides? They can too travel very fast. Perhaps it is friction which creates a layer of hot gasses?
Pollack's 4th phase of water has a lot of new science and potential and testable extrapolations regarding vicinal water or interface water as socially structured ie molecular structuring of water interfacing with particulates or surfaces that has unique and in my mind 'model-changing' implications.
I'm sure he mentions avalanches. The principle extends as vesicles that we know as water vapour - that is not 'steam' in the air but charged particles that self organise and effect the nature and behaviours of much that we have 'explanations for' but that have all sorts of anomalies.
Note that plasma from the Sun (often called Solar wind), accelerates as it leaves.
Negatively charged is much faster (electrons) positive ions slower - but these electric currents accelerate particles to extremely high velocities.
Note lightening (plasma discharge in arc mode) is found inside pyroclastic flows.
the Electric Universe accounts for much that mainstream science makes up crazy stories after being baffled by 'not what we thought'. As long as working math is developed, technologism doesn't care for what is true.
Welcome to the post-truth technocratic world.
Landslides don't travel nowhere near as fast as pyroclastic flows however.
@SirKolass True, but there have been some non-volcanic landslides with freakishly long runouts that don't make sense. Entrained compressed gas might explain it?
@binra3788electric universe math fails.
But there is a large amount of magnetic electric as the same things going on which lead to the wrong theory.
Your GPS shows how the real theory Relativity works if they don’t adjust for time moving at different speed for satellite and the ground they quickly become inaccurate.
This explanation is very important for Indonesia because many volcanic eruptions here often cause pyroclastic flows
Here because Smarter Every Day.
I finally understand how the bodies in pompeii were preserved in the positions they died in 😬
Looks similar to the flow of hot fly ash out of a Boiler Precip. It flows like water.
Galadriel survived one to the face without a single scratch
I reckon that the rapid expansion of super-hot gases as they contact the cool air outside the volcano generates enough force to drive the ash, rocks and other debris along, plus the Earth's gravity causes acceleration of objects already moving downwards.
Mt. Pinatubo Philippines in 1991.🇵🇭
Yooooo I deadass finally know how this works yess thank you!😘😘😘♥️♥️♥️ learning a new way volcanoes can kill and be deadley I more exciting than I thought
Deadly*
How cool!
Superb
But Galadriel survived y'all
So basically the ground effect
That's hot!
We’ll be able to stop Volcanoes from even erupting in the future.
Dont let that get to you or else you’ll end up getting fed via a straw
The debris in a real pyroclastic flow is outgassing because it is now outside the volcano at ambient pressure. This outgassing makes it flow like a very dense low viscosity fluid.
Who is here after watching ep 6 Rings of Power? haha
She dead lol.
Doing my research 😂
You are making a good job, upload videos
Makes me think of how precursor waves can occur during a nuclear explosion
Same
That was some cool research 👍
I thought she was describing my car in the first 11 seconds 🤷♂️🤷♂️
Ok intern, have fun sweeping up.
ever heard of pneumonoultramicroscopicsilicovolcanoconiosis much??
who else is here just for late homework?
Water droplet on a hot plate. This is a bit different because of the air density by temperature. But the only thing that I don't understand is how no plasma or electricity is discharged though such action.
I seen lightning involved by volcano but don’t know with flow.
This is brilliant. It reminds me of liquid nitrogen.
And here I was thinking "pyroclastic flow" was just a rap lyric.
its what happens when ice cube starts to blow, no one can escape the pyroclastic flow
I'm sorry but I think you got it wrong. You know, lavine avalanches are also notoriously fast and long carrying and not having hot gases to carry the avalanche. But instead, during avalanche studies they discovered that the material is flowing fast in the middle of the avalache cloud. The outer layers of the cloud suffer from air resistance moving slower. That generates a "rolling motion" of material in which in the center of the cloud there is no air resistance at all. The front tip of the avalanche is moving fast but in the moment it is in open air, the particles move in the outer layer of cloud allowing new fast particles to emerge. Like bicycle racers drafting and changing leader continuously in peloton.
So how do they travel such great distances over water? Steam??
Pyroclastic surges travel over water, they're just ash and gas.
Pyroclastic flows just sink and can even cause tsunamis.
So does that happen only with a specific particle size mixture?
If you can't find pyroclastic flow in the wild, homemade is fine.
rip the kraffts
anyone else's geog teacher make them watch this?
im watching for fun because im taking geo lol
No but back when I was at school, I got told even a Ferrari wouldn’t be able to stay escape.
🌋🌬️🧎🏻♂️
Was the electrical nature of the plasma studied?
Vulcanism is as I see it an electrical phenomena and the current model of magnetosphere is based on erroneous assumption.
Likewise the Leidenfrost-effect is an electrical-molecular phase change event.
I thing Gerald Pollack has opened the field but anything that isn't extending the consensus is unsettling to the invested model that is deemed too big to fail.
What frequency does it take? ⚠🌋💨
I'm here after watching the Rings of Power. These inept show writers should definitely do more research.
They are truly skilled at ruining that show on many levels.
Sinabung.
who else is here from sunn....
Yikkity yikes
0:24
?
As a DM, real life science is a huge help for creating personalized spells and abilities for games like Dungeons & Dragons.
When appropriate, can use it as a tool to teach kids how the spell would function in real life and why.
That’s such a good idea!! Gonna keep this in mind with my campaigns
@ctbypwrlftr7409
I recently homebrewed a magic item for the party to collect. An anti-magic orb that fully negates magic within 20 feet. A light spell can't illuminate within the area, but keeps working as long as the source doesn't enter. A caster generates a spell and project it to a location where it manifests, like an arrow that explodes on impact. This area effectively breaks magical line of sight, so it's like that arrow dissolves before it can detonate.
It's an avalanche
we all know why we are here
poll
You can't tame nature
how painful is it for someone to sit in one? if i see one, i’ll save myself from the impending doom feeling and run in if i cant escape
well, how painful is getting vaporised
If this is heading towards you there is no running away. Better just accept your fate at that point.
@meganfuller5843 😆🤣😆
👌
You'll be instantly flattened like a pancake. If it's a pyroclastic surge however you'll be cooked to death
A hellish burning sulphuric sandstorm howling in your face at anywhere between 600 degrees C and 1,000 degrees C will kill you instantly in nearly all instances, but those who are caught on the edge will suffer horrendous burns - the survivors of the 2019 Whakaari/White Island eruption in New Zealand were dreadfully burnt.
is there a limit of how far the flow can travel. Mount Rainier to Seattle?
It depends on the eruption type and VEI but mostly it's on exclusive type eruption and pyroclatic flows can travel as far as 100 km.
bu da mı leidenfrost
**Spoiler**
It's gravity.
Also, Snow Avalanches top out at the same speed, indicating a fixed motivational force.
The mechanism in a pyroclastic flow is predominantly the expansion of hot gasses as opposed to gravity.
Yep that's a fact!
As molten hot lava and other elements from the eruption Cascade down the slope of the mountain, they emit gases at high rates and this causes the molten material to skid along the side of the volcano like a droplet of water in a hot pan. In both instances, and all three instances if considering both snow valances and magma valances, each cascading effect of the downward fall seems to reach near Free Fall speeds for different combined reasons
but it all pretty much amounts to the same concept, lack of friction within the presence of gravity in an atmosphere.
She said lubricant.
You should have asked Ice Cube! 🤪
Things that never ever happened in and around steel constructions until 2001-09-11.
You read my mind, was just about to post something similar.
Ha.
You fools will grasp anything. 😂
Here because of Rings of Power. I confirm that people can survive in this dense and hot volcanic material with magic.
Very cool
Im not scared of pyroclastic flow. Stop exaggerating. Its slow as hell.
200mph yeah slow
You really think 200mph was slow?
Wow so ignorant, pyroclastic flow can travel 700km/hour at the fastest...yeah that's very slow.
Ok. I think you need take vacation to merapi, jerk
Try outrunning one then foolish child
God sure is great :) So many mysteries
Depending on what religion you believe in, it could be something other than god
Speaker shouldn't whisper and shout one after another, it makes it impossible to regulate sound level.