Can CCTV predict earthquakes?
April 22, 2013 12:08 PM   Subscribe

In this CCTV traffic video of the recent earthquake in China (preceded by a 30s ad), an interference pattern rolls across the screen just before the shaking occurs. Is this an artifact of the recording (or transfer between media), or something "real"?
posted by pjenks to Science & Nature (7 answers total) 1 user marked this as a favorite
The quake starts well before you would see visible shaking on a camera, so at a guess it could be all kinds of things.
posted by TravellingDen at 12:17 PM on April 22, 2013

could be a 'real' effect (google 'earthquake lights' for some weirdness) but to me it looks almost exactly like the interference you see when shaking a camera shooting through a screen (probably protecting the camera) and doesn't seem to be part of the 'earthquake itself' it doesn't seem like it's a ripple travelling along the ground...looks more 'all over the frame'...probably a camera artifact. might even be a 'rolling shutter' effect
posted by sexyrobot at 12:23 PM on April 22, 2013

I lived in San Francisco and I was in the Loma Prieta earthquake.

There are a couple of anecdotal things that people talk about regarding earthquakes. Pets and weather.

1. The pets go nuts before an earthquake.

2. Hmmm, it's warm, still and slightly muggy, earthquake weather.

I believe that these instances are a result of a disturbance in the magnetic field or a release of electrical energy.

So, it wouldn't surprise me in the least to know that there was some sort of distortion on a broadcast right before an earthquake. All that magnatism and electrons shooting around like that.

Oh, and just to show I'm not talking out of my ass.
posted by Ruthless Bunny at 1:07 PM on April 22, 2013

It's just a Moiré Pattern caused the camera being shaken at close to a harmonic of it's frame rate.
posted by Confess, Fletch at 1:35 PM on April 22, 2013 [2 favorites]

From what I can see, the interference has several repetitions per scanline, and so the frequency of whatever-it-is would be somewhere from say 30kHz to 60kHz (for 2 to 4 cycles per scanline) (1kHz = 1000 Hz; the upper limits of human hearing are on the order of 20kHz). Googling the words 'earthquake kHz' turns up some scholarly-looking papers, but I don't know enough about where they were published to know if it's woo-woo or actual science. One example paper is Observation of Seismic Events with Frequencies f > 25 kHz at Mponeng Deep Gold Mine, South Africa. I'm also unclear on whether these "frequencies" are mechanical or electromagnetic; for the reasons given by Confess, Fletch it seems plausible that either could lead to "interference".

On the other hand, as shown on the guardian page most of the earthquake part is too blurred by compression artifacts to see whether the interference continued, and the portion before it appears is short enough that it's hard to be sure it's not there virtually all the time and just happened to be clear for a moment. This general kind of interference is common in good old analog TV, and while it appears clearly it looks so regular that one is tempted to assume a man-made rather than natural source.

Finally, in terms of "prediction", a warning of a handful of seconds wouldn't allow anyone to seek shelter from an earthquake, so even if this recognizable interference pattern occurred just before many or even all earthquakes, it wouldn't be useful to reduce earthquake casualties.
posted by jepler at 3:21 PM on April 22, 2013

As described in this article by MIT Technology Review, Japan's earthquake warning system does provide a few seconds of warning. This few seconds does allow more people to be prepared, but more importantly, I suspect, it provides for automatic shutdown of "energy and industrial facilities, and transportation services".

Wikipedia has more details on the system.
posted by applesurf at 5:56 PM on April 22, 2013

The effect I linked to above is strictly mechanical, you can sort of simulate it by eating something crunchy while looking at an old CRT monitor.

The only information I can find about electromagnetic emissions from earthquakes says they are low frequency, certainly not anywhere near the RF ranges that CCTV's run at. Modern electronics has quite strict requirements for being immune to garbage being pumped into it from outside. You'd need quite a lot of power to see the effect in the video.
posted by Confess, Fletch at 7:14 PM on April 22, 2013

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