Posted on 07/23/2005 4:03:54 AM PDT by bd476
Sound from last December's huge tsunami-causing earthquake was picked up by underwater microphones designed to listen for nuclear explosions.
Scientists this week released an audio file of the frighteningly long-lasting cracks and splits along the Sumatra-Andaman Fault in the Indian Ocean.
The spine-tingling hiss and rumble is an eerie reminder of the devastation and death that is still being tallied in the largest natural disaster in modern times.
At least 200,000 people are thought to have died as a result of the magnitude 9.3 earthquake, the tsunami, and the lack of food, drinkable water and medical supplies that followed.
The audio recording of the quake starts out silent. A low hiss begins and the intensity builds gradually to a rumbling crescendo. Then it tails off but, frighteningly, builds again in waves as Earth continues to tremble.
The audio file [here] is sped up 10 times to make it easier to hear. As it was recorded, the sound was at the lower threshold of human hearing, but it could have been noted by someone paying attention.
"If you were diving even hundreds of miles away you could hear this," said study leader Maya Tolstoy of Columbia University's Lamont-Doherty Earth Observatory. "You would hear it as sort of a 'boom.'"
Future help
An analysis of the recording suggest a new way to monitor earthquakes in near real-time, providing critical information about an earthquake's intensity and potential hazard that could supplement seismograph data, which typically requires hours and even days to properly analyze.
"We were able to constrain some details such as the speed and duration of the rupture more accurately than traditional seismic methods," Tolstoy said. "Moreover, we found the earthquake happened in two distinct phases, with faster rupture to the south and slower to the north, almost as if there were two back-to-back events."
Tolstoy told LiveScience that the recorded sounds raced from the rupture more quickly than the tsunami wave. The entire quake's sounds took about 45 minutes to reach the hydrophone. Were a system set up to use such data, analysis might be done in about 15 minutes, Tolstoy said.
The tsunami took hours to reach some locations.
An analysis of the data is detailed in the July/August edition of the journal Seismological Research Letters.
Sound travels
It is not surprising the sounds were picked up.
An earthquake releases energy of varying types. Its seismic waves -- those that shake the ground -- are technically just a variation on sound waves. And sound travels well in water. Whales can hear each other call from more than 1,000 miles away.
Tolstoy said people at sea have heard the rumblings of distant volcanoes when the sound hits the hull of a ship.
And this was no small earthquake. It ruptured the planet along 750 miles (1,200 kilometers) of fault. Scientists estimate the Indian plate slipped 33-50 feet (10 to 15 meters) under the Burma microplate. The fault shook for at least eight minutes. A typical large earthquake lasts 30 seconds or so.
Earth's very gravity balance was altered and the North Pole shifted by an inch.
The recorded data was provided in March to scientists by the International Monitoring System of the Comprehensive Nuclear Test Ban Treaty. Tolstoy and her colleague, DelWayne Bohnenstiehl, converted the data to make the new audio file.
Tolstoy hopes that in the future scientists will gain easier and earlier access to such data.
"There is an opportunity here to make a contribution to international disaster monitoring, as well as help us better understand earthquakes and tsunamis and potentially mitigate these events in the future." she said. "It makes sense to let others listen in."
The sound file is here.
A spectrogram of the data shows energy released, with red being the most. A peak in energy is seen about 300 seconds into the event. Credit: Lamont-Doherty Earth Observatory
It is interesting!
My 14 yr. old cat woke up, laid her ears back, eyes dilated and she listened to the whole thing.
My 5 year old cat didn't like it at all either. She was sitting on top of the desk next to the speakers. She started howling, ears back too and then started to stalk the speaker.
The dog heard it from the other room and he came in, sat down and simply listened.
Cool. Thanks
It said Bush Bush, I heard it.
OMG! LOL....I never thought of that! Now THAT would be an experiment that I would LOVE to see....maybe I can get a Gub'Mint grant for...say 150 Million to "study in depth" this phenomenon? Preferrably from a tropical beach locale...
One could buy a heck of a stereo system for that price.
For research, of course.
Thanks for the the link. Even if listening to it did make the hair on the back of my neck stand up :) Wow.
Bttt
Crosslinked:
The Great Wave- Sumatra Quake and tsunami of 2004
various FR links | 12-26-04 | The Heavy Equipment Guy
http://www.freerepublic.com/focus/f-news/1308759/posts
Is it possible to hear sounds underwater while diving?
Sounds similar to the Landers quake.
I described that as a cross between thunder and a train going past outside your window, except louder!
Interesting sound file.
Thanks!
Hmmm... the mp3 format clips frequencies, doesn't it? Plus, they say they slowed this down ten times...does that mean they shifted frequencies, or just time extension?
oops..I meant "sped up" ten times. :-)
I'm also a pro musician...it sounds like it was speed compressed, not pitch shifted. IOW, the pitch/freq is the same, just the length of the clip.
yep, that's what I was asking! I knew what I meant to say, but the words just weren't falling into place! :-)
Rags took off looking at my computer suspiciously.
The cockatiel merely chirped quizzically at the funny humans.
Kearen cat is somewhere hiding, but she hides from thunder.
If you play it backwards, you hear Satan saying, "All your base are belong to us.".
Interesting experiment @ #18.
Interesting dog experiment @ #18.
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