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Below are two cropped screenshots from the super-cool video Draining Earth's oceans, revealing the two-thirds of Earth's surface we don't get to see with the oceans "drained" to 4000 and 5000 meters below sea level.

We've all read about the magnetic field reversals leaving alternating lines of residual magnetic field trapped in the crust that go in the north-south direction, but I was surprised to see these topographic ripples that extend in the east-west direction.

What caused these to form?

I've added some annotation to indicate the direction of the ripples I think I'm seeing.

cropped screen shots from Draining Earth's oceans, revealing the two-thirds of Earth's surface we don't get to see

uhoh
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1 Answers1

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These are transform faults that result from differential spreading rates of the middle ocean ridge. As such they are part of the plate boundary. Possible causes are different production rates of magma, thermal differences of the sea floor, differences of relative plate movement.

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

https://en.wikipedia.org/wiki/Mid-ocean_ridge

Paywalled: Dynamical Instability Produces Transform Faults at Mid-Ocean Ridges

And: Wilson, 1965: A New Class of Faults and their Bearing on Continental Drift

Inactive transform faults extending beyond the spreading zone are sometimes generally named "fracture zone".

But transform faults can also reach all the way to the next subduction zone (e.g. Azores-Gibraltar fault zone) and be responsible for devastating earthquakes.

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    Thanks! It's great when a new user stops by and immediately starts solving puzzles. – uhoh Mar 30 '20 at 11:28
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    Thanks. I tried to find something more sciency than the wikipedia links but it appears to be mostly paywalled or from a past millennium. The articles seem to be quite reasonable, on first site :-) –  Mar 30 '20 at 11:42
  • Okay I'll give them a read through in the morning and check the paywalled one when I get to the library. – uhoh Mar 30 '20 at 11:57
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    And virtually ANY geology text book, high school and above, created in the last 50 years would also solve this "puzzle". – Tim Nevins Mar 30 '20 at 16:47
  • True, but for that, the question lingered too long without an answer. A textbook has it, but finding a non-paywalled recent paper wasn't easy (or I'm too quick). But it sure has a few funny remarks up there ("megamillions") :-) –  Mar 30 '20 at 17:18
  • Also, it's hard to for a spreading center to keep to a straight line on a round Earth, and the rock tends to fracture in a rectangular fashion. – Spencer Mar 30 '20 at 18:01
  • If i recall it right there can be a connection between the Euler points of plate motion and the orientation of the transform cracks at a constructive boundary (angular motion, distance from rotation pole, and all that). But i leave that for someone else to find out and describe properly ... –  Mar 30 '20 at 18:05
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    Thank you for the reminder! I've just downloaded "Dynamical Instability..." (some problem getting the 1965 Nature paper but I really look forward to reading it!) and will read ASAP! As a side note, I sometimes wait a week or longer before accepting an answer. This has several benefits including there being more incentive for additional answers to be posted and when one is accepted it bumps the question back to the active queue which often results in more people having a look and up voting the excellent answers. – uhoh Apr 01 '20 at 12:21
  • I couldn't see this linger for another month :-) On to what's up next ! –  Apr 01 '20 at 12:23
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    Dynamical Instability Produces Transform Faults at Mid-Ocean Ridges non-paywalled. – Keith McClary Apr 02 '20 at 19:46