Comments
very_humble t1_j2qbeyj wrote
This seems like something that would be fairly trivial to negate if it happened today. Even at 677.1 cm/year, that's 50,000 years to move NYC to where Boston is
GeoGeoGeoGeo OP t1_j2qjl16 wrote
As to whether or not this would increase intraplate or marginal plate stress I really have no idea. If the plates don't move perfectly synchronously with one another there might be a bit of a jostling around per se. If there were, 677.1cm/yr (22 ft./yr) is potentially a lot of increased seismicity / strain within any infrastructure adjacent to or spanning major fault systems, along with subsequent increase in associated natural hazard risks. All that being said, TPW is effectively a decoupling of the fluid outer core to the silicate Earth (mantle and crust) so it really may be a bit of a stretch to think that there may be increased seismicity. Certainly interesting to ponder.
[deleted] t1_j2rtfwf wrote
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FranticPonE t1_j2tuhmp wrote
TIL What Polar Wander means, and holy shite I didn't think that was possible.
GeoGeoGeoGeo OP t1_j2twr06 wrote
UmbraPenumbra t1_j2u722r wrote
The pizza analogy is good work.
[deleted] t1_j2qd6c2 wrote
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rydan t1_j2qya19 wrote
So that thing conspiracy theorists claimed would happen all in one day back in 2000 actually did happen but took hundreds of millions of years?
fish_whisperer t1_j2rzhbb wrote
Nah, I think they were talking about magnetic polar wander.
GeoGeoGeoGeo OP t1_j2stutj wrote
I'm not sure what you're referencing, but the O-S TPW event spanned 10 million years, not hundreds of millions of years. See Fig. 3: Ordovician–Silurian apparent polar wander paths globally. (C)
rydan t1_j2tcwu0 wrote
I was basing that on someone else's comment that said it takes 100 million years to shift 61 degrees.
The conspiracy theory back then was that the Earth was too heavy at the south pole and a planetary alignment was going to basically shift all the continents on the planet causing a major catastrophe. Scientists of course refused to comment so as to not panic the public of our impending doom.
GeoGeoGeoGeo OP t1_j2tjpsh wrote
That was actually my comment above explaining the differences between ATP and TPW and the theoretical speed limits to TPW (not that actual reported rate in the study, which was 40–50° over 10 million years or upwards of 55.5 cm/yr).
Interesting. As is the case with most conspiracy theories perhaps one or more of the individual components are correct on their own, but the details, mechanisms, and relationships between their interactions are woefully lacking in understanding.
1gridlok2 t1_j2q7q2p wrote
Even though 10 million years is a really long time, I think after so many millions it doesn't matter. Just say its a half a billion years
Kinda_Lukewarm t1_j2qomzt wrote
Ah but someone worked for 6 months in a moldy back office to figure out how accurately they could estimate these events. And its +-5million years apparently
Incendiary_mind742 t1_j2qu9cd wrote
Horse shoes and hand grenades. Close enough on an order of magnitude maybe. Still fun to think about
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routerg0d t1_j2ulgax wrote
Wonder how this would impact mantle plumes. Generally I’d think this could enhance volcanism and seismic events through stresses.
[deleted] t1_j2v53xz wrote
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GeoGeoGeoGeo OP t1_j2q8pv6 wrote
Apparent Polar Wander vs True Polar Wander:
Apparent polar wander (APW) occurs as the magnetic pole drifts about the surface of the Earth, this is why your compass needs to account for declination. APW is associated with reversals of the geomagnetic field. True Polar Wander (TPW), on the other hand, is a re-orientation of the solid Earth as a whole relative to the spin axis. On Earth, TPW is achieved by wholesale rotation of the solid, silicate Earth (mantle and crust) around the liquid outer core. As Earth’s magnetic pole is tied primarily to rotationally induced excitations of the outer core, the magnetic poles remain aligned with the rotation axis through a TPW event. For example, 90° of TPW could result in Antarctica moving to the equatorial region, Africa moving to the pole, and all other geographic features moving accordingly. Theoretical constraints demonstrate that TPW can occur quite rapidly, limited to approximately 61° in 100 million years (Ma) and 8° in 10 Ma (Theoretical constraints on true polar wander). 1° latitude ≈ 111 km. 61° per Ma ≈ 6771 km per Ma or 677.1 cm per year and 8° in 10 Ma is ≈ 88 cm per year. Those rates are exceptionally fast when compared to tectonic speed limits (Tectonic speed limits from plate kinematic reconstructions) and modern rates of plate motion; The Cocos and Nazca plates (in the pacific ocean) are right now the quickest, moving at over 10 cm per year.
EDIT: An analogy for further clarity and distinction between APW and TPW: Think of a hot slice of cheese and pepperoni pizza with a laser pointing up from below. The pizza sauce is Earth's mantle, and the cheese and pepperoni toppings are the continents. If you were to shoot a laser upwards, from below the pizza slice, you could trace the movement of the laser by looking at the trail it left behind on the toppings. In this scenario, the magnetic pole (the laser) moved but the continents (the toppings) remained in their positions. TPW on the other hand would be like picking up a hot slice of pizza and the toppings all sliding off in one direction at the same time. The laser from below would still leave a trace on the toppings but this time it was the toppings that moved instead of the laser.