Posted on 04/17/2008 11:07:31 AM PDT by NormsRevenge
Earth gives off a relentless hum of countless notes completely imperceptible to the human ear, like a giant, exceptionally quiet symphony, but the origin of this sound remains a mystery.
Now unexpected powerful tunes have been discovered in this hum. These new findings could shed light on the source of this enigma.
The planet emanates a constant rumble far below the limits of human hearing, even when the ground isn't shaking from an earthquake. (It does not cause the ringing in the ear linked with tinnitus.) This sound, first discovered a decade ago, is one that only scientific instruments - seismometers - can detect. Researchers call it Earth's hum.
Investigators suspect this murmur could originate from the churning ocean, or perhaps the roiling atmosphere. To find out more, scientists analyzed readings from an exceptionally quiet Earth-listening research station at the Black Forest Observatory in Germany, with supporting data from Japan and China.
Different types
In the past, the oscillations that researchers found made up this hum were "spheroidal" - they basically involved patches of rock moving up and down, albeit near undetectably.
Now oscillations have been discovered making up the hum that, oddly, are shaped roughly like rings. Imagine, if you will, rumbles that twist in circles in rock across the upper echelons of the planet, almost like dozens of lazy hurricanes.
Scientists had actually expected to find these kinds of oscillations, but these new ring-like waves are surprisingly about as powerful as the spheroidal ones are. The expectation was they would be relatively insignificant.
New thinking
This discovery should force researchers to significantly rethink what causes Earth's hum. While the spheroidal oscillations might be caused by forces squeezing down on the planet - say, pressure from ocean or atmospheric waves - the twisting ring-like phenomena might be caused by forces shearing across the world's surface, from the oceans, atmosphere or possibly even the sun.
Future investigations of this part of the hum will prove challenging, as "this is a very small signal that is hard to measure, and the excitation is probably due to multiple interactions in a complex system," said researcher Rudolf Widmer-Schnidrig, a geoscientist at the University of Stuttgart, Germany.
Still, a better understanding of this sound will shed light on how the land, sea and air all interact, he added.
Researcher Dieter Kurrle and Widmer-Schnidrig detailed their findings March 20 in the journal Geophysical Research Letters.
I’ve heard it postulated from time to time that these low-frequency noises are what homing pigeons use to find their way around.
I wonder if it’s possible for the scientists to record the sounds some way and speed them up so that we can hear them— make a symphony kind of like that guy did with “And God Created Whales”
So?
Didja click it?
Nah, I hovered :-)
Pretty funny, tho!
Good job......I have gone to hovering mode lately ALOT.
There’s too many new posters and who KNOWS what they’re up to! :)
Hovering is always safer, but the arms get sooooo tired! <8-)
Complicating factors:
oblate ellipsoid;
core / mantle / crust;
atmosphere / oceans;
Cheers!
Where’s this Dynamo comin’ from?
“this is a very small signal that is hard to measure, and the excitation is probably due to multiple interactions in a complex system,” said researcher Rudolf Widmer-Schnidrig,
He talking about my Hillery!’s orgasms?
I actually understood what Saturn was saying. It said, "Kill your family. Kill your family."
Hey. Seems like a good idea. And if Saturn tells me to, I better. Gotta run.
Or "Mmmmm Mmmmm Mmmmm Mmmmm" by the Crash Test Dummies.
“Maybe this noise is what animals hear and then move out of dangers way when earthquakes are imminent.......”
I believe that.
I personally witnessed that one night with my pets before an earthquake hit. At that moment, I did not realize an earthquake was about to hit. After it hit, I realized why their unusual, unorthodox behavior. They behaved quietly scared.
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