The Earth Is Pulsating Every 26 Seconds, and Seismologists Don't Agree Why | Hacker News Reader

The Earth Is Pulsating Every 26 Seconds, and Seismologists Don't Agree Why

discovermagazine.com

245 pointsNoRagrets103 comments

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 amplitude can be similarly attributed, as pressure patterns conditionally form along the bottom of the ocean (in either direction) due to combined features of both the wave and the ocean bottom topography. [1]

[0] https://en.wikipedia.org/wiki/Wind_wave#Physics_of_waves

[1] https://en.wikipedia.org/wiki/Microseism#Generation_of_secon...

Never heard of this either, but I don't agree with your theory, as waves usually form only superficial on the ocean.

This is an unusual measurement which is unexplained by current models. This chart [0] helps show why and when waves are not superficial to only surface of the ocean.

[0] https://en.wikipedia.org/wiki/Microseism#/media/File:Interfe...

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 wave physics) is usually taken into account at depths of the order 1/20 the wavelength. That is, when the depth is smaller than 1/20 the wavelength we have to start taking into account the effect of the seabed which makes the dispersion relation of waves non-linear and brings entirely new physics. Of course that 1/20 is not a magic number just a rough figure when the effects of the seabed start to be noticeable.

Unfortunately, we are still off by several orders of magnitude so I would think the effect you describe is unlikely.

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 how the waves may have combinatorial feedback loops due to stokes drift (doppler effect) in deeper water.

It's frustrating the latest research on microeism seems to be from the 50's. There's very few resources describing what happens to waves as they move from shallow to deeper water.

To be fair, that kind of back of the envelope analysis shows that with our current knowledge we cannot assign this phenomenon to your hypothesis. But maybe that's precisely why the phenomenon remains unexplained because we have to think a bit outside the box.

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.

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.

It's called a Helmholtz Resonator fyi

Yes, but I think more people know what a bottle is than what a Helmholtz resonator is.

TIL

Thanks to the article editor who did not do the common "The Earth is pulsating every 26 seconds and NOBODY KNOWS WHY."

But it's still "and <noun> <verb> why." Not very creative.

It's still quite clickbate-y I'd say...

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 called "Skeptical Eye" that dissected the usual pop-science fluff making headlines elsewhere[1].

Sadly tough, since its inception it has changed hands several times (and had some interesting owners, including Disney) until it eventually went with the trend of dumbing things down. The "Skeptical Eye" column was dropped quite early on in favour of more controversial stuff that it used to be sceptical off, in hopes to drive up sales[1].

[1] https://en.wikipedia.org/wiki/Discover_(magazine)

I had a subscription to Discover a number of years ago. I'm sad to see that they've started dumbing things down.

Same. I've not normally been interested in medicine, but I'd always read their Vital Signs section. It was almost always guaranteed to be captivating, even if the rest of the articles for the month weren't all that interesting.

But to be honest, that downward trend has been going on across all major publications for decades.

> Thanks to the article editor who did not do the common "The Earth is SLAMMED by a pulse every 26 seconds and NOBODY KNOWS WHY."

FTFY

Funnily enough, it's also close to the 0,0 GPS coordinates

https://www.google.co.uk/maps/place/0°00'00.0"N+0°00'00.0"E

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.

Why is north "up"?

Because some people hundreds and thousands of years ago drew it like that on maps, and people kept doing it that way for cross-compatibility reasons, and now it's a convention.

And the best part is that it depends on culture. In ancient Hebrew, east was venerated for a variety of reasons and was given the distinction as "up" (although I'm not sure that distinction really maps to our concept of up).

https://www.ancient-hebrew.org/philosophy/east-time-eternity...

Perhaps because the sun comes up in the East (at that latitude at least)

I would imagine so, yes. Hence the cultural implications of "beginning" or "origin" since the sun was no doubt viewed as the locus of life.

One of the interesting implications is how they view the past as east and the future as west (or conversely, the past as in front of you and the future as behind you). I'm not precisely sure I yet understand why this is, but I wonder if it's a matter of visibility? e.g., we can "see" the past but not the future.

Instead of downvoting this comment you'd better downvote its parent for starting the whole completely useless conversation.

Wasn't the infamous natural nuclear reactor near 0,0? A seam of fissionable minerals that millions of years ago would periodically fill with water, heat up, boil it off, cool down, rinse, repeat -- and that sounds an awful lot like what's happening here.

EDIT: It was at -1.5780591, 13.

> It was at -1.5780591, 13.

...at least at the surface.

Also funny that the island near it happens to be "São Tomé and Príncipe" which I got familiar with only this month b/c the non-ascii chars caused an issue at work.

With all these "scientists don't know why" articles, I always picture some scientist somewhere slacking off on HN and going "Is that..? shoot, my bad guys - didn't mean to do that"

Like Tesla with his earthquake machine

Could it be an underwater geysir? 26 seconds is right in the period length for a geysir. Maybe due to the higher pressure due to greater depth it has more of an "explosion" characteristic than traditional geysirs so that it causes a seismic event?

I don't think geysers really exist under the sea. The pressure would keep steam from forming and therefore stop a pressure build up. Every geothermal feature I have seen under the ocean has been a steady stream of superheated fluid. As an example, I took a temperature reading on one black smoker and it was 320°C and still fluid.

Nobody's yet mentioned that there's another of these 26 second pulses with a source near Australia and New Zealand [1]. Pretty mysterious! http://ciei.colorado.edu/pubs/2006/3.pdf

Fascinating! I wonder if the pulse is strong enough to show up on phone accelerometers. Would make for a nice project to be able to clean up the signal and try to pick up the pattern.

This is super interesting. The area they have narrowed down is nearly in line with the mountain range that falls off into the ocean.

The way ocean waves / currents hit the topology of that mountain range? Some geologic activity that is somehow more active when the ocean is more active?

Hard to imagine anything to do with ocean waves and storms could be consistent enough to produce this effect. I understand there is some average wave periods but storms normally disrupt patterns.

All very interesting.

Can't help but evoke images in my mind of some mad scientist trying to recreate Tesla's Telegeodynamics. The concept of transferring power via seismic waves always fascinated me as a kid.

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?

> For popular culture to lack any references to it whatsoever

As the first paragraph of the article has mentioned, at least xkcd has a reference [0].

[0] https://xkcd.com/2344/

That's interesting, assuming the location in the comic is correct. It is very close to 0 degrees latitude, 0 degrees longitude.

Many people who have built or used GIS applications are familiar with "Null Island." It should probably have been called "Bug Island." If you have bugs in your GIS code, this is where they tend to lurk.

>>" It is very close to 0 degrees latitude, 0 degrees longitude."

The 0 latitude could be relevant, but that the 0 longitude is in there is more an historical accident.

The shape of the African continent is also interesting there.

There appears to be a mountain range that runs straight into the ocean there. Oddly right in the middle of the bite. I wonder what that area looked like when ocean levels were lower.

I think the 0 longitude most likely is accidental.

Yet, here is another thing to think about: Zero longitude is the longitude of Greenwich, i.e. London, a significant city through the ages. Cities and towns, especially ones with old age, aren't positioned randomly but in geographical suitable locations: valleys, rivers, coast, etc. Since the position of London is not random, the 0 longitude isn't totally random as well. Still seeing no connection to this 26s pulse tho.

Just saying that software bugs tend to show up here. If the pulse was localized by cross-correlating data from lots of different stations worldwide, it could potentially be some kind of numerical artifact.

Is there really any subject on which there is no xkcd? They are the Simpsons of web cartoons.

There's no topic without a relevant xkcd, and there's no event that The Simpsons didn't predict, and if it exists there's porn of it. The internet has rules.

Funny because (I'm sure like many people) before I even clicked on that my gut feeling was "clearly a sleeping kaiju".

> But nearly 60 years after the pulse was first observed, no one has managed to figure it out. That may be because, as far as seismologists are concerned, it’s just not really a priority. “There are certain things that we concentrate on in seismology,” explains Wiens. “We want to determine the structure beneath the continents, things like that. This is just a little bit outside what we would typically study … [since] it doesn’t have anything to do with understanding the deep structure of the Earth.”

> That doesn’t mean it’s not worth studying, Ritzwoller adds.

The same reason it's not important enough to finish the article ;)

Such a weird justification. If they don't know what's causing it how do they know it won't help explain the structure beneath the continent or the deep structure of the Earth.

It's not weird. Its just how a large jungle gets explored by chimps with 6 inch brains. Eye doctors, Astronomers, Painters, Microscopists, Architects etc etc had all been studying light for thousands of years. But it took a bookminder to do some basic 8th grade magnetism and electrical experiments to make a connection.

The jungle is vast and there are only so many curious chimps.

Life is finite. Brainpower is finite. If you feel otherwise, add to the field.

> Why haven’t I heard about this before?

It's probably just part of the "Earth's hum", which is waves.

(Don't confuse this with the world wide paranormal hum people claim to hear)

You probably should have learned of the hum at school, if you did, you'd have probably forgotten. As a 10 year old you'd either find it amazing and think of it forever or just forget.

It would be interesting to rank it on the importance level though. Or, it'd be interesting to work out how you could rank it. What are important things to know... in order... for personality types.

Huh, I feel like that’s something I’d remember learning.

Did many other people here learn that?

First of me hearing about this.

> (Don't confuse this with the world wide paranormal hum people claim to hear)

Taking this sort of random swipe at at people who experience this is kind of rude. Even though it's pretty much confirmed it's not a real audio signal coming from outside of a person's body, there isn't quite enough evidence it isn't a real auditory sensation for these people (instead of psychological or "paranormal" issue).

I do get the hum sometimes, usually happens when my shoulders are tense. Also usually only in one ear, which is why I was able to pretty quickly rule out an external source (though when it first happened, I did spend some time opening and closing windows, listening at ventilation ducts, trying to locate it).

Edit: I'll add it here that sometimes it is a real sound. We live a couple of km away from a harbor, and the sound we get to our place from an idling cruise liner is very similar to what my ears sometimes generate by themselves. It's really hard to tell them apart except by trying if it gets louder (and more high freq components) by opening a window. The point is, at least in an urban environment it can be pretty hard to tell if the hum is real or not.

> Taking this sort of random swipe at at people who experience this is kind of rude.

> Even though it's pretty much confirmed it's not a real audio signal coming from outside of a person's body

Why would you not think you have the well documented medical condition Tinnitus?

"The Hum" is "a real audio signal coming from outside of a person's body", except it's not real. (And the first Google result for "The Hum" is this legend, not the vibrations from the oceans hum)

It was on the X-Files for instance - https://en.wikipedia.org/wiki/Drive_(The_X-Files)

William Shatner's The UnXplained - https://www.history.com/shows/the-unxplained/season-1/episod...

I have friends who believe in the paranormal. I don't disagree with them, even if it's medical like this. But I also won't agree with them. I'm not sure if that's cowardice.

For me the first google result the Wikipedia page (https://en.wikipedia.org/wiki/The_Hum) which offers several explanations, including actual measurable man-made external sources, a type of tinnitus, and some more rare or speculative circumstances.

My understanding is that hum-like low-frequency tinnitus is not all that well documented. Feel free to provide links to sources to prove me wrong.

This is ridiculous. Neither environmental hums nor hallucinations or tinnitus or other psychological sources are paranormal.

I'm fine dismissing out of hand paranormal hums and paranormal phenomena generally. You don't appear to even be in this group and yet you feel personally attacked?

This is internet; the place where people go to exercise their right to feel offended. Welcome!

I read the quoted part as the whole class of people with this auditory issue being binned as truth-is-out-there nutjobs, and decided to offer a bit of perspective. It was probably an overreaction on my part.

You're missing more XKCD in your life!

https://xkcd.com/2344/

These moments when I find myself digging into a very specific point on a pretty specific topic and someone posts a XKCD link and I think to myself - there is just no way this will be about this exact thing.. Sure enough.

Thanks for the link. I needed a good belly laugh this morning.

Why do you think that it's important? Basically any kind of long term signal recording will turn up a multitude of patterns and signals with unclear source, some easier to explain than others. Seismometry has many of them, but this seems far too niche for any general textbook to care about.

LOL. Pop culture is our barometer for relevancy, now?

Jesus wept.

It looks like periodic geyser eruptions. Geyser eruption frequency is also (minutely) affected by atmospheric events like storms. In this case, the geyser-like structure is underground somewhere in the vicinity of the São Tomé volcano.

With our luck in 2020, it just might be Cthulhu's heartbeat.

Indeed. When I saw the headline, my first thought was: it's 2020, so it's probably Earth itself about to rip apart into pieces come December.

I remember reading about this years ago, and someone mentioned the location does coincide with one of the creatures in the Cthulhu mythos, but not Cthulhu itself. Don't remember which one, though.

26 is certainly the most famous kaballistic number. As the gematria of the word "God" in hebrew

https://en.wikipedia.org/wiki/Gematria

When I looked this place up, there’s also a massive obelisk shaped pillar. This feels like a conspiracy theorists dream: https://en.wikipedia.org/wiki/Pico_C%C3%A3o_Grande?wprov=sft...

Make the Old Ones Great Again

Can this be used to measure time?

It would be great to see this written into something like a Godzilla film as a sleeping monsters heart beat.

My head canon, it’s Lavos.

Let's harness its energy!

touché.

Or that Earth itself is alive or just a giant egg for a monster.

I actually remember a SF short story where astronomers detected something looking like a giant bird coming from outer space into the solar system. It then approached Mars, the planet cracked open and a baby bird came out. Next, both birds started heading for Earth... and people started drilling in a desperate attempt to kill whatever was under their feet...

Unfortunately I don't remember the author.

Marvels' Celestials also have this story:

"Celestial Eggs within planets

It was stated by the Celestial Madonna that Earth and many other worlds were implanted with a Celestial Egg/Embryo at their center, gestating for millions of years before birthing and consuming the planet. Similar processes was witnessed in Earth-9997 and other realities."

https://marvel.fandom.com/wiki/Celestials_(Race)#Celestial_E...

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.

By which definition?

https://en.wikipedia.org/wiki/Noise_(spectral_phenomenon)

no. noise can be very much periodic. or have a pattern.

you can view noise as a signal you don't want to receive right now. HDTV transmissions are noise to radio astronomers, etc.

Relevant xkcd: https://xkcd.com/2344/

https://en.wikipedia.org/wiki/When_the_World_Screamed

Dharma Initiative. I'm pretty sure.

"as above so below"

I thing J. J. Abrams is behind it.

Did no-one else watch lost?

Is probably an hibernating Godzilla heartbeat.

Or the Great Bird of the Galaxy, about to break out.

You think Gene Roddenberry is down there?

Or at least Peter David...

Clearly it's a migraine.

It's the peck peck peck of the planet-scale baby bird almost ready to emerge from the Earth's crust.

I was thinking Godzilla, but that's more likely.

"Oh that? Don't worry about that. It's just a by-product of invoking the simulator GC periodically. Wouldn't want things to get too out of hand and have to stop the world LOLOL amirite?"

EDIT: Ouch.

Haha. Pulses.

Pulse is a sign of life.

That's CPU cycles in the computer built to discover the the ultimate question of life, the universe and everything.

Rather slow clock rate in our perception, but not that bad if you're computing for millions of years.

Or could be a pulse that triggers a series of layered switches.

Worth one year of compute on a mediocre PC if my math doesn't fail me. Not that much for such a task.

We tend to forget how fast modern computers are.

What's the minimum billable time unit if I want to run some serverless functions from your cloud service if the cycles are measured by the millions of years?

Ringing left over from a meteor impact, or plate tectonics.

If more earthquakes happen in phase with the pulsating, it would only increase the amplitude, forming a feedback loop.

I'd look at earthquake phase data to see if they are "helping" the pulsating.

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