81–90 of 112 posts
I see this phenomenon is called "seismic noise" in a couple places, but that can't be right; noise is by definition irregular (occurring at uneven or varying rates or intervals). This is actually a signal of something, we just don't know what.
Thanks to the article editor who did not do the common "The Earth is pulsating every 26 seconds and NOBODY KNOWS WHY."
Also thanks for actually using the word seismologist instead of just calling them generic "scientists". Browsing through this website, it looks like Discover Magazine is a little bit more qualitative than the usual pop-science fluff sites. According to Wikipedia it was a 1980 Time Magazine spin-off that featured more in-depth reporting on scientific topics, but still aimed at a general audience and even had a column…
Earlier quoted context omitted.
0°00'00.0"N+0°00'00.0"E Funny how it's N+E, not S+W
Why? The natural “up” direction is north, and east goes great with it like that’s where the sun comes up and also arrows pointing to N and E look like the coordinate axes in a default oriented graph.
It would be great to see this written into something like a Godzilla film as a sleeping monsters heart beat.
Earlier quoted context omitted.
Why? The natural “up” direction is north, and east goes great with it like that’s where the sun comes up and also arrows pointing to N and E look like the coordinate axes in a default oriented graph.
Why is north "up"?
Never heard of this, so I had to do some digging. My money is on this being an ocean wave phenomenon. The Gulf of Guinea, specifically the Bight of Bonny, is up to ~20,000ft deep. Average ocean waves have a period less than 15s and the average ocean depth of the Atlantic is ~11,000ft. Oddly similar ratios! So it's plausible this 26s wave period is caused by the increase in depth [0]. The abnormally large seismic ampl…
The same effects that cause a tone when blowing across a bottle rim might cause a vibration like this when an ocean current moves over a deep trench.
Earlier quoted context omitted.
Wave-depth and period are related, waves of 15s or even 26 are much too shallow to be affected by the seabed at those depths. EDIT: Some back of the envelope physics to see how plausible your hypothesis is: For deep water waves: wave_speed = gravity * wave_period / 2pi wave_speed (26 sec period) = 40.56 m/s wave_speed = wavelength / period => wavelength = 1054 m = 3458 ft. The effect of the seabed (i.e. shallow water…
Thanks, you're probably right that it's not only depth being a factor in this. I think we both over-simplified as these are logarithmic ratios, not linear. On to speculation: the interaction between the waves and the ocean floor may be hitting one, of many, of these magic numbers in this scenario. It's possible two periods of waves interact to cause this 26s interval, since waves are always grouped. Also, consider ho…
Fluid dynamics is complicated (Navier-Stokes still has a 1 million prize attached to it), surface wave propagation is complicated but when you include the effects of the seabed it's even more complicated. A lot of non-linear behavior pops out which always brings very nasty math.
I'm more on the side that this is not the explanation but I wouldn't bet too much on it.
I see this phenomenon is called "seismic noise" in a couple places, but that can't be right; noise is by definition irregular (occurring at uneven or varying rates or intervals). This is actually a signal of something, we just don't know what.
you can view noise as a signal you don't want to receive right now. HDTV transmissions are noise to radio astronomers, etc.
Why haven’t I heard about this before? This seems too important a detail for my school textbooks to have left out and for popular culture to lack any references to it whatsoever. What am I missing?
Jesus wept.