OK, for years I’ve heard / read the “crazy talk” about crustal shifts and the earth’s crust “slipping” or moving.
I’ve always dismissed it. I’ve always gone out of my way to say “Pole Shift” is going to be a magnetic pole shift, not an actual movement of the physical poles.
Then on some long lost posting on WUWT Lief Svalgaard said that the liquid iron part of the Earth’s core had a viscosity less than that of water (one presumes at near normal room temperatures).
That has just nagged at me.
IFF the crust is solid on a very viscous mantle, and then there is a layer as liquid as water, what in the world would prevent the crust from “wandering around”? And I don’t mean just the plates drifting on top of the viscous layer of the mantle, I mean the whole thing.
It ought to have significant ‘tidal’ flexing and significant magnetic interactions of the liquid layer with the magnetosphere. We know the mag field has complete reversals at times. So what on earth prevents the crustal layer from ‘wandering around’ relative to the rest?
Inertia? There ought to be a lot of it. But a rotating gyro has a lot too and it can tumble and flip from minor perturbations. How big a meteor, at what speed and impact angle, could impart enough momentum to make a ‘crustal tumble’ in a gyroscopic sense? How much change of the (fairly massive) electrically charged currents flowing through the planet to induce a homopolar motor effect and move things? Is the “crazy talk” of a “pole shift” really all that crazy?
So I’ve tried unsuccessfully, for a few weeks, to ignore this and have it go away…
Doesn’t give me much hope of an answer, but does give me cause for more worry.
The viscosity of liquid iron at the physical conditions of the Earth’s core
Gilles A. de Wijs, Georg Kresse, Lidunka Voadlo, David Dobson, Dario Alfè, Michael J. Gillan & Geoffrey D. Price
Physics Department, Keele University, Keele, Staffordshire ST5 5BG, UK
Institute for Theoretical Physics, Technical University of Vienna, Wiedner Hauptstrasse 8-10/136, A-1040 Vienna, Austria
Research School of Geological and Geophysical Sciences, Birkbeck College and University College London, Gower Street, London WC1E 6BT, UK
Correspondence to: Michael J. Gillan1 Correspondence and requests for materials should be addressed to M.J.G. (e-mail: Email: email@example.com).
It is thought that the Earth’s outer core consists mainly of liquid iron and that the convection of this metallic liquid gives rise to the Earth’s magnetic field. A full understanding of this convection is hampered, however, by uncertainty regarding the viscosity of the outer core. Viscosity estimates from various sources span no less than 12 orders of magnitude1,2, and it seems unlikely that this uncertainty will be substantially reduced by experimental measurements in the near future. Here we present dynamical first-principles simulations of liquid iron which indicate that the viscosity of iron at core temperatures and pressures is at the low end of the range of previous estimates — roughly 10 times that of typical liquid metals at ambient pressure. This estimate supports the approximation commonly made in magnetohydrodynamic models that the outer core is an inviscid fluid3, 4, 5 undergoing small-scale circulation and turbulent convection6, rather than large-scale global circulation.
I had to look up “inviscid”. It means, roughly, without viscosity.
If that’s the case (or even things close to it) then we can easily have the inner core and the crust moving any which way relative to each other for periods of time. At that point, we’re dependent on the crust as a kind of spherical ‘ring’ with something of a bulge or two to be ‘stabilized’ by the moon tugging on the bulge bits for stabilization (at least, that’s as I understand it, but I could be way wrong here).
At the end of it all, thinking about a solid core, a gooey mantle with some crusty bits on top, and an “inviscid” layer of convecting stuff in between, I’m not seeing why a whack with a suitable rock from space can’t set the whole thing wandering for a while.
And what happens when we move a whole load of water to the poles as Ice Age Ice Caps. How much “bulge” has to be away from the equator before the moon has trouble with that stabilizing the gyro action?
I’d complain that I’m not sure how to approach this mathematically, but I’m not so sure it’s going to be answerable that way what with all the error terms.
At any rate, I just thought I’d afflict all of you with this same “crazy talk” maybe not so crazy after all dilemma…