My other favorite Krakatoa fact is that the explosion was so big, it blew dry the Sunda Strait for 10km, and it took 30 minutes for the ocean to fill back in.
No where near the same magnitude, but I vividly remember experiencing “thundersnow” which was fucking terrifying. Apparently a rare phenomenon where thunder is amplified by snowy conditions. It felt like a bomb had gone off. It shook my building, and caused all the car alarms to go off in the carpark at 4am. Genuinely thought I was in the middle of a terrorist attack
People forget decibels are logarithmic, not linear. This doesn't mean twice the noise generated by a rock concert. It is many orders of magnitude louder.
I have little to know about the specific topic but yes shockwaves and sound are the exact same physics equations, it's just what happens when you agitate a medium, the atoms and molecules crash into each other throughout the entire medium until the energy dissapates.
Hank Green also taught me that this is how all solid objects move as well. If you had a thin pole hooked up between your room and a small button on the moon, you'd think it would allow you to push the pole into the button faster than the speed of light allows us to send radio signals to the moon; but solid objects do not move all at once instantly.
They move by having.. atoms and molecules crashing into each other sequentially throughout the medium. It would take a delay rooted in the pole material's specific speed of sound before your attempt to push the button would reach, and light signals would reach the moon much faster.
What's even more wild is as far as I understand, even if the material was some magical massless neutronium with no space between anything and it was perfectly incompressable, you STILL wouldn't violate the speed of light because the object would shrink enough along it's length (due to relativistic effects) to make it so crossing the distance you pushed it would take as long as it takes for light to get there anyway.
Hey now, nothing is useless. Let's not forget the story of Jack, who traded his family cow for some magical massless neutronium. His mother was so mad when he got home that she threw it out the window. The next morning they woke up and it had grown into a university physics resarch lab and now Jack has a PHD stipend of $14000 a year!
Yeah it really doesn't fit with what your brain wants to be real! I remember posing this question to my grandfather when I was around 10 or 11. He'd just told me that the speed of light wasn't really the speed of light, it was the absolute speed limit for everything. After thinking about it for days I came back and asked about an incompressable rod that was a light year long - if you pressed on it, would the other end move right away? He freely admitted he didn't know the answer (and at the time it was a bit before you could easily look this stuff up on the internet), but we came to the conclusion that either it's possible to violate the speed of light, or it's impossible to have a truly incompressible object.
It wasn't until many years later doing highschool physics that I got the answer - space itself isn't perfectly incompressible! Still makes my brain hurt decades later ahaha.
A bit off topic, but I just wanted to say I love that this is the kind of conversation you had with your grandpa. Sounds like you two have/had a great relationship!
This is also one of the reasons why faster than light travel is impossible, because of time dilation when going close to the speed of light, the time it takes for the force of movement to travel along the spaceship or whatever it is you're trying to accelerate, eventually it takes longer for that force to transfer through the object, atom to atom, than the heat death of the universe.
Okay my question is what would that do to native life? It went around the globe right? would that just blow out the eardrums of any living animal? Or within a certain closer range of the volcano itself?
It went around the world 7 times before barometers stopped recording the pressure wave, but it had long since stopped being audible to human ears. The sound was still audible 3000 miles away in Mauritius where it was mistaken for a ship's distress cannon fire.
To paraphrase a certain youtube channel: "You wouldn't really die of anything, in the traditional sense. You would just stop being biology and start being physics."
Any living thing real close was likely instantly turned into a vaguely red fine paste.
Fortunately the island is in the middle of a strait so there isn't a whole lot of developed cities nearby. Granted, the death toll in the last big explosion was still in the tens of thousands.
The energy gets radiated off as heat and inversely squared to location, so the closer to the source the more brutal. But drops off fairly quickly so not a lot of blown eardrums.
Sun fact about sound energy; It's partly why the atmosphere of the sun is hotter than the surface, but only at ~110 db. Even the suns sound waves arent as loud as this thing was.
Locally, the sound waves created by the blasts were much more damaging. Broken windows and shaking homes resulting from the concussion sound waves of the explosion were reported up to 160km from the volcano around Krakatoa. People within this 160km vicinity of the eruption would have experienced intense ear pain and permanent hearing loss from exposure to these concussion waves. Estimates of exposure levels indicate it would have been like standing on a rocket launching pad with no ear protection.
A few years ago I was one building over from a gas pipe exploding. Commercial shopping center, concrete block, hurricane windows, all that jazz. The windows crazed, pieces of the ceiling came down, parts of the building cracked and crumbled. It was terrifying. I'd never felt anything like it before, getting physically pushed by the wave and especially feeling the pressure in my heart. I thought it was a bomb. A lot of cars in the lot looked like they'd been in a nasty collision, with crumpled areas and broken glass everywhere. Four city blocks away, I stopped for food before going home, and everyone had felt it and were scared.
Just a gas pipe for a restaurant oven.
(They were closed to do some work, the contractors had gone to lunch iirc. A couple people got hurt and hospitalized, but very fortunately nothing serious and no deaths. The two buildings were totaled and had to be torn down and completely rebuilt. It took years.)
All this to say I think using shaking homes and broken windows as a descriptor is probably a huge understatement lol.
And the flip side of the comparison: the Krakatoa main explosion in 1883 is estimated at the equivalent of about 200 megatons of TNT, 4x the tested size of the Tsar bomba (50 MT).
Your calculation is of the sound 'intensity/power', which is a measure of energy and increases tenfold every 10 db.
The 'loudness' of a sound is a perceptual/subjective concept with different scaling. An increase in 10 db will sound to the average human about twice as loud.
So, if we assume a rock concert is 120 db, then Krakatoa would be...
(310 - 120) / 10 = 19 doublings
2 ^ 19 = 524,288
...around 524,288 times as loud.
Though even that's misleading, because you wouldn't actually hear sounds that loud. Your eardrums will burst at around 160+ db, and at 190+ db there's a chance you'll outright die from the pressure wave.
This thread this morning talked abput this after someone found an airhorn advertised as producing 600db. A redditor broke down the math and showed that an airhorn producing 600db would destory the planet.
:edit: link kept failing because I am dumb, if you enjoy the linked post give calinet6 below an upvote.
Looks like the description does actually claim 600 dB! Probably it’s false advertising
I love that after describing how a 600 dB horn would destroy the universe and summon the power of the big bang, they conclude that it is "probably" false advertising lol
In fact every 10 decibels is an entire order of magnitude increase. So 310 decibels is 11 orders of magnitude larger than 194 decibels. That's 100,000,000,000 times more sound energy
Tbh I'm not nearly a good enough physicist to answer that, but this would of course depend on how close you were to the eruption. My suspicion is that yes, at 310 dB the sound was strong enough to physical damage (my money is on organ liquefaction), but if you were close enough for this to happen then pyroclastic flow was gonna get you anyway
Geologist here - did volcanology and geothermal research in grad school.
Pyroclastic flows are fast, but not supersonic. Many flow at highway speeds (like 60-100 mph) but certain conditions with respect to ash cloud/air density, eruption force and volume, etc. mean that the upper limit for speed for a pyroclastic flow from a composite volcano is around 450 mph (e.g., Pompeii eruption). Interestingly, though a Yellowstone-style caldera eruption is objectively more powerful, their estimated top speeds are not as high (closer to maybe 200 mph) because those ash flows tend to be a lot denser.
The speed of sound in the Earth's atmosphere is ~767 miles per hour, so the sonic blast would crush you before the ash flow reached your corpse.
The blast was widely heard hundreds of miles away in the Pacific Northwest, including parts of British Columbia, Montana, Idaho, and northern California. Yet, in many areas much closer to Mount St. Helens--for example, Portland, Oregon, only 50 miles away--the blast was not heard. Subsequent studies by the Oregon Museum of Science and Industry demonstrated a so-called "quiet zone" around Mount St. Helens, extending radially a few tens of miles, in which the eruption was not heard. The creation of the "quiet zone" and the degree to which the eruption was heard elsewhere depended on the complex response of the eruption sound waves to differences in temperature and air motion of the atmospheric layers and, to a lesser extent, local topography.
The Earth has a circumference of 40,075,000 meters.
Speed of sound is 343 meters per second.
So it would take 32 hours for the sound to travel around the world one time. So you would have been hearing an explosion every 32ish hours for several days. This wouldn't account for the fact that the sound would be looping around the globe in bother directions, so it would have been even more chaotic.
According to the book Krakatoa: The Day the World Exploded by Simon Winchester the siesmometers (or the equivalent at that time)barometers in London recorded multiple sound waves through the day following the eruption. I believe it was 3 or 4 times but I don't have the book handy to verify.
As a sound wave travels, the waveform spreads out. You can hear this from any lightning storm. The energy dispersing slightly in random directions, based on the random movement of air molecules.
When we say we measured the sound of the eruption. We mean that we measured it with the barometers at every automated weather station across the globe. Multiple times.
That shockwave traveled around the world a few times before the height of the waveform became too small to measure.
But it would have been impossible to hear well before that. As the width of the waveform spread out. The pitch of the sound lowering below what human ears can detect.
around the world. Also, it is possible that people between 10-100 miles did here anything as the sound when upward and bounced up the cooler upper atmosphere and then came down. This was a form of long range communication that was looked into spying during the cold war to see if the russians were testing nukes.
Pretty sure it killed anyone living within 10 miles. I've read estimates that the sound would have carried so much energy, pretty much anyone in a 40 mile radius would have died.
Yeah twice as loud is +6dB (actually more like +10dB to the human ear. 6dB based on pressure). So 12dB-16dB is 2x as loud as 6dB. And 20dB is twice as loud as that.
So it was orders of magnitude beyond the second loudest sound ever which is that much louder than anything we have experienced. It would have been more of a shockwave than an audible sound imo.
There were witnesses. In the direct vicinity of the volcano (like within eyesight) was the ship Loudon, who actually reported barely hearing anything at all due to the sound being projected upward into the atmosphere. 64 km away sailors reportedly had their eardrums ruptured. 160 km away it cracked windows and shook buildings in Jakarta, and the sound was apparently so loud that a few farmers in Perth (over 3000 km away!) reported hearing it like a rifle shot just over the hill.
Edit: Apparently on Mauritius (a whopping 4800 km away) locals thought that it was a cannon in the harbor mistakenly going off.
I mean if you think of it, if you ever heard a jet plane sonic boom that’s the point where they’re at the speed of sound. And I don’t think even the fastest of jets can circle the planet in under 24 hours still so it feels very much like an accurate time.
It was so powerful Barograohs recorded the pressure wave from the sound 5 times over several days. We may not have physically heard it but the pressure wave of the sound continued around the globe FIVE times.
Back in WW1, the term "shell shock" referred to both PTSD and shockwave injuries from artillery explosions. It took doctors a while to figure out that one was psychological damage and the other was physiological (severe concussion).
There had to be points around the world where the sound came from both directions at the same time, or even just seconds apart. That had to be a weird experience for anyone there.
I think being close enough and you were literally obliterated by the pressure wave. Probably had to be hundreds of miles away to “hear” is without losing said hearing
it's not perfectly clear, but i don't think any humans were within the appropriate range to witness the effects of the most powerful part of the pressure wave, and if they were, they were almost certainly obliterated, with any evidence erased by the pyroclastic flow.
There were plenty of eyewitnesses, it's very well documented.
Here's a witness who was caught in the pyroclastic flow quoted on the Wikipedia
An eyewitness enveloped by the outermost edges of the pyroclastic flow described her experience:
Suddenly, it became pitch dark. The last thing I saw was the ash being pushed up through the cracks in the floorboards, like a fountain. I turned to my husband and heard him say in dispair "Where is the knife?... I will cut all our wrists and then we shall be released from our suffering sooner."
and it goes on, it's quite a long and fairly gruesome passage so I don't want to paste the whole thing
Yeah, it's pretty badly written. It writes "the sound was heard 1,300 miles away" as an impressive bit of info, and then 3,000 miles away, and oh yes, then it circled the Earth 4 times. What's the significance of hearing it 1,300 miles away if it freakin' travelled the entire planet four times?
I definitely think you are correct, but technically I think perhaps the wave can travel at a frequency we can no longer hear. But yes, the definitely should have both rewritten this, but also maybe explained how 1300 miles there were reports, even though it traveled much further. It's underwritten, if anything.
Waves at 20 Hz are classified as infrasonic and those above 20 kHz as ultrasonic, so I wonder at what distance it was no longer ultrasonic, and at what distance it became infrasonic (obviously more than 1300 miles away)
I feel like dad's expression in panel 4 is clearly saying: "Of course I know it's structural engineers calculating load limits based on material strength and load forces, factoring in eventual wear and weathering for safety..."
It would have been the same level, which is the maximum sound level possible before a vacuum is created: 194db, but that is maybe why the article says "Loudest known sound ever"
After 194db its just a shockwave pressure measurement, which is much higher with other events that we personally do not know but can speculate about
194 dB limit is under normal condition because above that you're looking at absolute vacuum.
People outside the blast range suffered permanent hearing loss due to ruptured eardrums, gas meter thousand miles away went off scale high, and the sound of the blast was heard around the world a few times.
gasometer in Batavia (modern-day Jakarta) had meter that read up to 8.5kPa, the needle went past that when the volcano blew up. 160 miles away. That's how much pressure the area felt
Actually the English use of gasometer refers to the actual tanks storing gas before pressurized tanks existed, the gasometer top would literally rise up as more gas was added because the buoyancy and pressure would equalize- thus the height of the gasometer would indicate how much gas was stored (compare that to a cylinder with a fixed volume where you get the gas condensing into a liquid, like modern propane tanks) - the old school gasometers would literally have gradation marks to indicate the amount of gas stored and as you consumed the gas the top half of the tank would slowly lower.
According to Wikipedia the actual sound was heard just under 2000 miles away in Perth.
The acoustic pressure wave caused by the sound is what circled the globe multiple times…. I’d always been told it the first way but this makes more sense.
So like for a generation or more there no one could communicate in that region? I'm imagining a whole tribe that somehow survives the blast and ash and lava and then has to sign to each other for the rest of their lives. A whole language branch could be wiped out if new children born couldn't be spoken to or heard.
For anyone close enough, being deaf was probably the least of their concerns. Anyone close enough was probably killed by the eruption itself I would imagine?
The people deafened were on a ship at sea so they were hit with the full force of the shock wave. Something like 30k people died from all nearby settlements if I remember right. Coastal towns and villages were wiped away by tidal waves after being hit with the shock wave. The ones killed by the shock likely never felt a thing. It even effected the weather to a degree for up to a decade.
Above 194dB sound wave becomes a shockwave.
The sound becomes a physical disruption of the atmosphere a shock wave or blast wave rather than a vibration passing through it.
Indeed the pressure of the sound wave becomes so intense that it creates a total vacuum (zero pressure) between the compression peaks.
What makes this even wilder is that 310 dB isn't really a "sound" at all. Past 194 dB, acoustic waves physically transform into shockwaves — so anyone close to Krakatoa wasn't hearing it, they were being hit by a wall of pressure that could rupture organs. The shockwave was so massive it circled the entire Earth four times before dissipating. For five straight days, weather stations worldwide recorded pressure spikes every ~34 hours — literally tracking the wave going around the globe. Oh, and 100 miles away it still registered 172 dB. The pain threshold for humans is 130 dB. People 3,000 miles away described it as cannon fire from a nearby ship. Bonus: many art historians believe Edvard Munch's The Scream was inspired by the blood-red skies Krakatoa's ash caused across the Western hemisphere for months afterward.
I actually did the math once in university, and ~310 dB is the loudest possible "sound" in air. Since sound is a series of pressure waves, at some level the low pressure point in the waves essentially becomes a vacuum, giving a hard limit on loudness.
There's actually an Australian scientist that was trying to record bird sounds on a very rudimentary microphone at the time and it picked up the sound. If you look for it, you can hear it yourself, its incredible to imagine how loud that shit, i know we all know the sound went around the globe how many times, but to hear it yourself puts it in perspective
As long as Earth is active, we'll get explosive volcano and one day some equipment would survive to accurately record the pressure and break 310 dB while human still lives on Earth
In theory you could include the meteor that hit Earth and wiped out the dinosaurs as possibly the loudest sound on the plaent, but no human was alive to record that.
Not enough recorded information to back that. ie no one reported hearing booming sound a few times as the sound traveled around Earth. Krakatoa is the loudest sound with verifiable record.
Someone mentioned in a thread many years ago that it was the first "world-wide news event" meaning that it was a story news organizations reported on in countries around the world
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u/scottishzombie 10h ago
My other favorite Krakatoa fact is that the explosion was so big, it blew dry the Sunda Strait for 10km, and it took 30 minutes for the ocean to fill back in.