Researchers Find Some Volcanoes 'Scream' At Increasing Pitches Until They Blow 59
vinces99 writes "Swarms of small earthquakes often precede a volcanic eruption. They can reach such rapid succession that they create a "harmonic tremor" that resembles sound made by some musical instruments. A new analysis of an eruption sequence at Alaska's Redoubt Volcano in March 2009 shows the harmonic tremor glided to substantially higher frequencies and then stopped abruptly just before six of the eruptions. Scientists at the U.S. Geological Survey's Alaska Volcano Observatory have dubbed the highest-frequency harmonic tremor at Redoubt Volcano 'the screams' because the episodes reach such high pitch compared with a 1-to-5 hertz starting point. Alicia Hotovec-Ellis, a University of Washington doctoral student in Earth and space sciences and an author of two papers examining the phenomenon, has created a 10-second recording and a one-minute recording that provides a 60-times faster representation of harmonic tremor and small earthquakes."
Thetans ... (Score:1, Informative)
It's the thetans getting ready to take a massive shit in Tom Cruise's mouth and fill him with even more blessings.
Re:harmonic tremor, screaming? (Score:5, Informative)
She documented the rising tremor frequency, starting at about 1 hertz (or cycle per second) and gliding upward to about 30 hertz. In humans, the audible frequency range starts at about 20 hertz, but a person lying on the ground directly above the magma conduit might be able to hear the harmonic tremor when it reaches its highest point (it is not an activity she would advise, since the tremor is closely followed by an explosion).
However this is slashdot so no need to RTFA, just carry on with redundant questions veiled in the shape of a seemingly innocuous post.
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"It's the thetans getting ready to take a massive shit in Tom Cruise's mouth and fill him with even more blessings."
Um, no. I don't think that's the way it works. I... scream. Ice cream. Yeah, that's the ticket.
Look, let's be honest. I tend to scream a bit before I explode, too. So do you. Female or male, bad explosion or good explosion, you either scream a bit or you're hopelessly Victorian.
"I say... you have trodden on my foot with your pegleg. Do you mind, terribly?"
(censored)
Makes sense, fluid dynamics and all that... (Score:5, Interesting)
Re:Makes sense, fluid dynamics and all that... (Score:5, Funny)
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Folding laundry?
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More like normal farts at normal frequencies and intervals. Then, suddenly you are attacked by frequent small, higher pitched flatus, while you fast walk with clenched buttocks to the closest toilet. As the intervals become shorter and the frequencies become higher still, you know it is moments before the disaster.
You all know what I'm talking about.
I'm not a lactose bigot or anything, I try to be tolerant but even so I can only take so much dairy.
Re: Makes sense, fluid dynamics and all that... (Score:1)
It's because the "tube" (colon) gets shorter in length as the fecal matter descends further. So the fart is higher pitched. Like a trombone!
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No. Source: http://www.washington.edu/news/2013/07/14/some-volcanoes-scream-at-ever-higher-pitches-until-they-blow-their-tops/ [washington.edu]
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So, it's like a teapot when it gets boiling?
Would that you could get thousands of atmospheres of pressure in your teapot.
I tend to think of it as the Earth doing its own version of Fracking. Without so much as a permit or 'By your leave, good people of the lands.'
Krakatoa must have had some pitch before it popped, which it will do again some day, such is its activity cycle.
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Which leads to an interesting question.
Can they hear this screaming underwater?
http://www.soest.hawaii.edu/GG/HCV/loihi.html [hawaii.edu]
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So, it's like a teapot when it gets boiling?
Or maybe a....pressure cooker?
We should be scientists and get grant money and grad students and and um...
Re: Makes sense, fluid dynamics and all that... (Score:2)
Up into the human range (Score:2)
At their peak, just before they blow, these "screams" get to a high enough frequency that humans could hear them. Of course, to us it would sound like a low frequency rumble.
In other words, if you are standing on a volcano, and start to hear it grumble, get away. Fast.
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Actually, the screams are the noises of people. This is because the volcanoes sound like accordions.
Re:Up into the human range (Score:4, Interesting)
At their peak, just before they blow, these "screams" get to a high enough frequency that humans could hear them. Of course, to us it would sound like a low frequency rumble.
In other words, if you are standing on a volcano, and start to hear it grumble, get away. Fast.
About 12 years ago there were swarms of tremors around the Long Valley, near Mammoth Mountain, California. 600-800 earthquakes per day from sub 1.0 to 3.0+ and elevation changes around the caldera indicated pressure was building. Then suddenly nothing happened and they subsides. Still a few here and there, but some activity took place and then ended. Massive false alarm or very long range warning? You scare a lot of people with eruption talk, which doesn't materialize, and you'll have most of them home when it suddenly goes BOOM without warning.
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The rumblings and quakes were warning of a geological pressure release. That the release did not include hundreds of tons of ash in the sky and rivers of molten stone is a good thing.
It is important to remember that 'signs of a potential eruption' are not a 'promise of imminent eruption' but are the best forecast typically available. This is similar to medical evaluations, many harmless conditions have symptom lists that only differ from life-threatening by one factor that requires difficult testing. Ign
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and you'll have most of them home when it suddenly goes BOOM without warning.
Hos is that different than not warning at all?
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and you'll have most of them home when it suddenly goes BOOM without warning.
Hos is that different than not warning at all?
Effectively what we know as the 'cry wolf' example. California is no stranger to people who like their name in the news for predicting the next big quake, but when it doesn't happen they're shamed for a bit and then drop into anonimity. People stop listening to doom projectors - next thing you know, someone knew what they were talking about because they heard the seismic precursors and they get ignored as yet-another crackpot.
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Or just follow your ferret.
http://www.pbs.org/wnet/nature/episodes/can-animals-predict-disaster/introduction/130/ [pbs.org]
http://www.lsu.edu/deafness/HearingRange.html [lsu.edu]
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So what I'd like to know is: do Elephants (who's auditory range of 16-12,000 hertz covers much more of the tremors) always know when a nearby volcano is going to erupt?
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Even so (Score:4, Funny)
I bet the volcano's still have better pitch control than Justin Beiber.
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Would you prefer something more like "The Song of Ice and Fire: A Volcano's song"?
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and also (Score:4)
some volcanoes will erect before they blow.
sounds like my bathroom (Score:3)
after a night at Taco Bell
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How many db? (Score:5, Interesting)
For those who didn't RTFA (Score:2)
Check out the time compressed sound recordings- pretty awesome.
Volcanoes in Space (Score:1)
This obviously does not apply to volcanoes in space.
Because in space, no one can hear you scream.
My girlfriend does the same thing. (Score:2)
More than coincidence?
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It all makes sense.
Volcanoes are drama queens and attention whores.
How can you tell ... (Score:2)
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... if they're fracking it?
So, Hawaiians are right! (Score:2)
Volcano [wikipedia.org] IS a woman!
Interesting (Score:1)