Yeah, the Bikini Atoll was a testing ground for nukes, but that’s not the reason they are strangely hollow outlines of islands.
As far as I understand it, it’s because there were islands formed from underwater volcanic eruptions, but over time the inner islands sunk and eroded away and what makes up the island today are actually the surfaced parts of the once surrounding coral reef.
May I bring my son to visit? I know it’s typically only for events. He will crack up at the statues and be underwhelmed by the two racks containing the entire Internet.
For what it’s worth: I counted about 85 or 86 “clicks” in 10 seconds. It’s a loud click followed by a quieter click, like as if it’s oscillating towards and away from you. The sound of the click itself is loudest at about 2.6 khz - whether that is simply the sound of friction, or some sort of electrical phenomenon, I don’t know.
The fuzzy area at the bottom half of the spectrogram is the dull roar of distant wind. The clicks themselves show up as spikes, and the intense colors on the right are from where the voice starts speaking. The dark band above 10K is just the data lost from audio compression.
Well, I can say definitively that I know what is making that clicking sound. It’s hard to see since the cable is in silhouette, but there are silver-colored spirals wound around the cable, and the sound is made by the plastic sheathing of the black cable wobbling inside of those metal spirals. The spirals are made of aluminum, I’m pretty sure. Those spirals are put there to stiffen the the hanging cable, and appear on the hanging cable between every set of poles (not just these, that are wiggling). There are two spirals mounted on each cable between the poles. I assume the spirals are mounted there to provide damping, just in case the wind does cause the cable hanging between the poles to swing too much. But, there was no wind blowing when I shot this video (Dec 5, 2023). The voice you hear is mine, just speculating on what might be causing the oscillating cable…
Did you measure the distance between the poles? I suspect it’s different from all the other spans, so this one happens to have a resonant frequency that exactly matches whatever vibration source is already there (could be the tension too). As for sources of vibration, wind is probably it, even if it’s not strong. If it just happens to create the right frequency, the cable will vibrate just like a violin string.
I immediately thought of the original Tacoma Narrows Bridge, which collapsed after wind caused a resonance to build up and literally shook itself apart: en.wikipedia.org/…/Tacoma_Narrows_Bridge_(1940)
No, I’ve never tried to quantify the variables in that way. Just out walking the dog, and notice this strange behavior from time to time. I always assumed the poles were placed a specific distance apart, but honestly, I’m not sure. I suppose if I ever have the urge to pace it out to get a good estimate, I will…
mildlyinteresting
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