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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

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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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    $\begingroup$ Thanks! It's great when a new user stops by and immediately starts solving puzzles. $\endgroup$ – uhoh Mar 30 at 11:28
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    $\begingroup$ 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 :-) $\endgroup$ – user20217 Mar 30 at 11:42
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    $\begingroup$ And virtually ANY geology text book, high school and above, created in the last 50 years would also solve this "puzzle". $\endgroup$ – Tim Nevins Mar 30 at 16:47
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    $\begingroup$ 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. $\endgroup$ – uhoh Apr 1 at 12:21
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    $\begingroup$ Dynamical Instability Produces Transform Faults at Mid-Ocean Ridges non-paywalled. $\endgroup$ – Keith McClary Apr 2 at 19:46

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