Anybody Could

[JamesSavik]

Anybody Could



University of Utah at Cedar City

____________________________________________


"Can I talk to you?"

I looked up from my desk and saw one of my students at my office door.

"Sure Cal, come on in. I'm a little busy trying to figure out why an earthquake fault that hasn't moved in 250,000 years just decided to go rouge and pop the valley with a 4.2."

Cal Morris was one of my brighter geology students. Coming from a dusty little town in Nevada, I suppose you either went completely bonkers or became interested in rocks. He parked his backpack on the floor and sat in the chair across from me. I could tell that something was bugging him.

"It's about the earthquake Doc. I think... no, I'm sure I caused it."

I grinned and said, "Cal, you're pretty good but..."

"No Doc, hear me out. Do you remember a paper by a guy named Pasternak last year?"

I searched my memory and yes- I did remember that paper. "Isn't he the guy who suggested that sound waves could trigger a slip fault?"

Cal nodded and said, "Yeah, that's the one and I can tell you it works."

I said, "Cal, start at the beginning and tell me what happened."

The kid shifted nervously in his seat and said, "One of my friends that works at a junk yard got all sorts of sound equipment out of a totaled car: A 5500 watt amp, four big woofers and a lot of other junk. I paid him $300 for the stuff and put it together to test Pasternak's theory."

"Over the weekend, I went camping out near Dry Springs and set up my experiment with four bass speakers spaced out over a kilometer on the old Dry Springs fault line."

"I set up a sine-wave on a function generator at 1 Kilo-hertz and fed it to the amp and began the experiment. At that low frequency, you couldn't hear it. You could feel it. Nothing happened so I lowered the frequency to a point where the fault began to pick up the harmonic. Once it started, I freaked and shut down but by that point, the whole fault had picked up the harmonic and they quake started."

I said, "Hold it." I picked up the seismograph strip and said, "When did you start?"

Cal said, "I powered up at 10:00 and began cycling through frequencies. Apparently I hit the right one at 20 minutes till eleven."

Sure enough- as I went backwards through the tape, the fault began moving in fits and starts at 10:00. As he moved to lower frequencies, the fault became more and more unstable until at 10:38 the small quake began in earnest."

I said, "That explains all the weirdness that I saw on the seismograph. We're damned lucky there was nothing out there to shake up but gophers and sage brush."

Cal said, "That's why I picked that spot Doc. If it worked, it couldn't hurt anything."

I grinned and said, "What on earth possessed you to try to cause an earthquake Cal?"

He looked at me and said, "Pasternak's article has been out there for over a year. If I could do it with a few hundred dollars worth of junk..."

The implications hit me like a train, "Oh shit. Anybody could do it."

[JamesSavik]

A little something spooky for Halloween. Hope you dig it.

[Merkin]

I'm sure hoping this is fantasy because if it's at all possible the folks in California better start packing.

[Rutabaga]

Just want to point out that 1 kilohertz is not a low frequency -- it's just below the tone of the C two octaves above middle C on a piano.

R

[JamesSavik]

Just want to point out that 1 kilohertz is not a low frequency -- it's just below the tone of the C two octaves above middle C on a piano.

R

In harmonics problems like this one, you start at a baseline and work down in increments. 1 Khz is just a convenient starting place.

Sound waves differ significantly for electromagnetic waves. In EM photons, higher energies are invested in higher shorter wavelengths like UV, X-ray and gamma.

Energies stack up higher in synchronized long wavelength sound. It becomes more of a vibration effect in the materials that absorb it.

[Nick Deverill]

Sorry, but Rutabaga is right. If you are talking about sub-harmonics, perhaps, but even so...

If you change the 1k in the story for 15 Hertz it would be a lot more believable, although I think the frequency of ground movements caused or causing an earthquake is way less, much lower that any normal amplifier will deal with, and much more to the point, way lower than any speaker could reproduce. To get below 10Hz, you need pots of money, very specialised audio kit, and... understanding neighbours!

If you could generate audio waves of less than 1Hz, ie fractional Hz, at a decent volume, there might even be something in the idea.

I found the resonant frequency of the living room at my first house, 13Hz and the windows rattled. Rather a fun experiment and illustrated that a cheap modification to my speaker stands paid off. Spike them to the floorboards!

Gamma waves are between 25 and 100 Hertz - ie within what you can do with home hifi. But the UV frequency has 16 noughts and X-ray, 18, way more than any loudspeaker could ever dream of reproducing.

But, the story is a bit of fun, stands very well as it is, except the frequency used. Nail 15 in and it'll do I think.

As an aside, 1k is a standard broadcaster test tone, so standard that my party trick was setting a adjustable audio frequency generator to 1k by ear alone.

[JamesSavik]

I picked 1 Khz because it is nowhere near the frequencies that are required to do this.

[Bruin Fisher]

Wow what a subject (can of worms)...

My poor brain struggles a bit, there's plenty to confuse me here. In case I'm not the only one, here is some disambiguation:

Gamma waves are neural oscillations in the human brain, not to be confused with gamma rays which are part of the electromagnetic radiation spectrum and extremely high frequency (above 10 Exahertz, or 10 to the power 19 Hertz!)

Electromagnetic radiation includes radio waves, light, X-rays but is of a fundamentally different nature from sound, therefore not directly comparable. EMR travels at the speed of light, sound travels at the speed of sound...

[Bruin Fisher]

I wonder if James' story uses the 'sum and difference' effect. If you generate two frequencies of sound, you will be able to detect not two but four oscillations (in addition to harmonics and sub-harmonics, but that's a different matter). For instance if you generate a sound at 1KHz and another at 1.1KHz you will get those two frequencies, also a frequency of 2.1Khz and another of 100Hz. If you re-tuned your second frequency to 1.001Khz you could generate a sound of 1Hz - a frequency much lower than a loudspeaker could actually originate.

This principle is used in radio receivers of the superheterodyne design.

http://hyperphysics.phy-astr.gsu.edu/hbase/audio/sumdif.html

[Bruin Fisher]

Actually loudspeakers can work at very low frequencies when driven by specially designed amplifiers - but the 'sound' they generate at frequencies below about 20Hz is not heard by humans as sound - it might be 'felt' as a vibration but when you get down to single-digit frequencies the loudspeaker cone is just flapping uselessly - it will be merely moving air around immediately in front of the transducer. I suspect at these frequencies you don't get a sound wave at all because air can't be made to oscillate so slowly.

[Chris James]

Do I understand the science/physics of sound...no, but I buy this premise because James presented it in a very interesting way. I am surprised we don't have more sound activated earthquakes. Have you ever sat beside some hip-hop fool in his car filled with low frequency blasts of sound (I won't call it music) and felt the windows rattle?

For those of you with a few extra dollars in the bank I would suggest investing in hearing aid technology companies because these fools will all be deaf by age 25.

[Addym Kehris]

Say James, what a good story. I'm sort of a science geek, I suppose. At least I enjoy reading what authors speculate about in their fiction. I have to say that I've heard the theory before, but I liked the way your presented it to us. Very entertaining. And yes, it'll make ya think a bit. But gads, do we have to dissect it so minutely? I appreciated that you used frequencies that were well outside the range to trigger the effect. I mean, isn't that what any good author would do with such a potentially dangerous scientific principle?

At least two of your fans (and now 3) gave you a comment or two about the merits of a fine work of 'fiction'.

I do tire, however, of all the 'education flaunting', especially for such a short work of fiction.

Well done, James, on a fine little story.

[Nick Deverill]

The point is, I think you can have a more believable tale and not sow the seeds of destruction in real life. It is very easy to generate audio frequencies as an electrical current that are possibly low enough, but you'll find it very, very hard to translate them to actual air vibrations; and as a consequence, to faults in the earth's crust. Getting to 10Hz is easy, getting to 1Hz is nigh on impossible and you'll need to go lower than that.*

As I said but didn't perhaps make enough of it, when all is said and done,the story is a good one and deserves to reach a wider audience.

* Of course, if you are a roady for Disaster Area, a mere bagatelle. From the Hitchhikers Guide to the Galaxy (a trilogy in five parts...).

Disaster Area was a plutonium rock band from the Gagrakacka Mind Zones and was generally regarded as not only the loudest rock band in the Galaxy, but also as being the loudest noise of any kind at all. Regular concert goers judged that the best sound balance was usually to be heard from within large concrete bunkers some thirty-seven miles away from the stage, whilst the musicians themselves played their instruments by remote control from within a heavily insulated spaceship which stayed in orbit around the planet - or more frequently around a completely different planet.

Their songs are on the whole very simple and mostly follow the familiar theme of boy-being meets girl-being beneath silvery moon, which then explodes for no adequately explored reason.

Many worlds have now banned their act altogether, sometimes for artistic reasons, but most commonly because the band's public address system contravenes local strategic arms limitations treaties.

[Rutabaga]

I didn't mean to raise such a fuss. As a musician I just wanted to note that 1 kilohertz is not considered a low frequency in the acoustics world. The lowest note on a piano is 27.5 hertz (or 0.0275 kilohertz). The low E string on an electric bass sounds at 41.2 hertz (or 0.0412 kilohertz). Those would be considered low frequencies. The frequency mentioned in the story misses by almost two orders of magnitude.

I just assumed it was a slip of the keyboard. it doesn't really detract from the point of the story.

R

[Cole Parker]

To reduce this to the absurd, here's how low we can go, musically:

Note Frequency(Hz) Comments Lowest note for:

C-2 4.09 Gregg Bailey's 64' PVC subcontrabass clarinet

C-1 8.18 lowest organ note Hill organ, Sydney Town Hall, Sydney AU

[Bruin Fisher]

This is why I love the AD forums - a thread worthy of the Hitch-hiker's Guide to the Galaxy itself.

[Nick Deverill]

To reduce this to the absurd, here's how low we can go, musically:

Note Frequency(Hz) Comments Lowest note for:

C-2 4.09 Gregg Bailey's 64' PVC subcontrabass clarinet

C-1 8.18 lowest organ note Hill organ, Sydney Town Hall, Sydney AU

Both of which are below the ability of the human ear to hear as sound. The organ though I'm sure can play its note with sufficient volume for one to be able to discern it in ones bones.

It just so happens that the point in the third movement in Saint-Saëns 3rd Symphony (commonly dubbed the organ symphony) where the organ enters, scored as forte but often played fortissimo is a bass chord in C major. So the organist could actually use/play that pipe in Sidney Town Hall. Bet that temptation has been acted upon properly in the past, although I could only find evidence of a selective approach with only the third movement being played.

For UK readers, if you even hear Classic FM announce that piece, tune away very quickly and play a decent CD of it when you get home. The movement does not survive their audio processing and is a textbook example of gain ducking. Not that surprising, the organ note is preceded by silence and is played about as staccato as an organ can get.

[Cole Parker]

That's a shame as that's a wonderful piece. But then, he's a wonderful, glorious composer. Most everything he wrote is a crowd pleaser.

C

[ChrisR]

Love the story - or at least I would if I wasn't worried some clown is out there with his woofers right at this moment!

One tiny point that has nothing to do with frequencies. You wrote:

"Sure Cal, come on in. I'm a little busy trying to figure out why an earthquake fault

that hasn't moved in 250,000 years just decided to go rouge and pop the valley with a 4.2."

Not sure about the rest of you, but I've never seen an earthquake fault wearing red makeup in my life! :)

Chris

[JamesSavik]

Not sure about the rest of you, but I've never seen an earthquake fault wearing red makeup in my life! :)

Fixed it. The joys of spelling checker blunders.