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Questions tagged [geodynamics]

Geodynamics is the application of mathematics, physics, chemistry, geology, and computer science in understanding how mantle convection leads to plate tectonics.

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Why is the temperature between the earth core and surface not distributed linearly?

So I read somewhere that the inner core temperature of Earth might be as high as 7000 °C. Depending on the composition of the different layers towards the surface, the temperature should decline ...
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What are the causes of the supercontinent cycle?

Throughout geologic history, Earth's continents have broken apart and come together to form supercontinents multiple times, in a somewhat regular period, known as the supercontinent cycle. The length ...
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Are the processes of the rock cycle currently in dynamic equilibrium?

The standard representation of the rock cycle usually looks like this: Does each stage of the rock cycle currently balance? That is, are the various processes in dynamic equilibrium, so that the ...
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Phase relation for mantle?

I have information about temperature, pressure, normal and shear stresses, viscosity, conductivity, density, heat capacity and adiabatic heating for a particular area of mantle in the form of 2D ...
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Could earth's core lose its heat?

Will all of the drilling and digging to use the earth's natural heat as geothermal energy be affecting Earth's core, causing it to cool down? If so, would it result in an ice age? If not, how does it ...
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Over what scales can we begin to apply fluid dynamics to accurately model properties of the mantle?

Over what size temporal/spatial scales do geophysicists and geodynamicists begin to apply fluid dynamics to model the mantle rather than elastic/plastic deformation theory?
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How much change has there been to the shape of plate boundaries over geological time?

This is a question that has bothered me for many years. As a new teacher I was asked this question by a 12 year old in our plate tectonics class. I said I would go away and find out. I would really ...
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Does volcanic activity fluctuate?

According to this person's surmises, volcanic activity appers to be increasing. However, according to this report, volcanic activity is probably not increasing. My question is: Does Volcanic activity ...
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1answer
444 views

What equation should I use in this isostasy problem?

I have this problem, and I am not sure where to start. The only Airy equation in my text is $r_1= \frac{h_1 \cdot p_u}{p_s - p_u}$. This doesn't seem to apply, or if it does it isn't obvious. Is ...
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How to calculate hydrostatic equilibrium?

I'm trying to solve the following problem. The sea level in the past was 200 m higher than today. The seawater became in isostatic equilibrium with the ocean basin. what is the increase in the depth $...
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How can we determine the size and composition of Earth's inner core?

From Wikipedia: Earth's inner core is Earth's innermost part and is a primarily solid ball with a radius of about 1,220 km (760 mi). (This is about 70% of the Moon's radius.) It is believed to consist ...
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Can non-antipodal Chicxulub impact seismic wave be connected to Rio Grande Rift and Laramide Orogeny?

I have conducted a brief survey of Internet sources and cannot locate any definite discussion of a possible connection between the Chicxulub impact and the inception or acceleration of the Rio Grande ...
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measuring fracture length and width using PKN and KGD models for hydraulic fracturing?

I am trying to understand PKN and KGD models for hydraulic fracturing. I am wondering why equations for fracture width and length does not include 'breakdown pressure' (pressure at which fracture ...
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2answers
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Are old geophysics textbooks useful?

I have had much success with old textbooks in mathematics. Generally, for any branch of mathematics that I (as a non-mathematician) would like to learn or re-learn, I can buy a classic textbook from ...
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How do I derive the formula for lithostatic (overburden) pressure?

The title pretty much says it. I have the formula: $P = \rho g h$ where $\rho$ is the density, $h$ is how deep the pressure is in the Earth and $g$ is the gravitational acceleration(?). I don't get ...
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Determining rotation of a bending detachment fault system

I would like to obtain the angle of rotation (𝛿θ) of a detachment fault (or oceanic core complex) after X meters of rock displaced during spreading at a mid-ocean ridge. I have a differential ...
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4answers
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Are the oceans rising or the continents going down? How can we know?

The century old sustained rising of oceans, at a rate of 2-4 mm/y, remains a unexplained phenomenon; there is no correlation with temperature variations, so it is not due to the thermal variation of ...
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1answer
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Is the concept of seismogenic zone still relevant after the 2011 Japan earthquake?

The concept of subduction seismogenic zone, where megathrust seisms occur in a layer between an upper and a lower limit is well documented in the 1990/early 2000 literature : Some example : Pacheco,...
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1answer
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How to define the force at the base of an oceanic crust

In the book of Turcotte and Schubert, Geodynamics I'm trying to solve problem 2.8. The pressure in the water, in the oceanic crust, and in the mantle beneath the oceanic crust are (from equation 2.19,...
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2answers
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Can the sealed bottle garden be called a perpetual motion machine? [closed]

I was not sure just where to ask this question, but I was wondering if the sealed bottle garden be really called a perpetual motion machine. http://www.dailymail.co.uk/sciencetech/article-2267504/The-...
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3answers
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Simulating the earths crust

I would like to create a computer simulation which would fold two plane-ish surfaces into two crumpled-ish surfaces. This in order to simulate the earths crust movement and collisions resulting in ...
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1answer
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Phase changes deep in planetary interiors and their implications for surface tectonics

Earth's core mantle boundary represents a phase change from a solid (though convecting) mantle to a liquid Iron/Nickel core. This dramatic transition is likely the origin of the D" boundary, as well ...
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Similarities between grand circulation solvers and mantle convection solvers

My impression is that both ocean grand circulation models (e.g. MITgcm), and Mantle Convection models (e.g. CitcomS), both use Navier-Stoke's as the governing equation. What are the other major ...
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1answer
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Flexure of a viscous lithosphere - derivation

I have been trying to figure out solution for the fourth order differential equation of flexure for a viscous plate. The fourth order differential equation for a viscous plate is given as $$Dv*\...
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1answer
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State of Stress in rotated 2D system

I'm working on the rotation of the state of stress using the book Geodynamics of Turcotte page 101. The 2D coordinate system $x'$ and $y'$ is inclined at an angle $\phi$ with respect to the $x$, $y$ ...
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Is there a differential angular rotation on Earth?

I asked a question about solar day difference between two latitudes on the same longitude here on the Earth surface. The answer was clear due to constant angular rotation time is the same. Tangential ...
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1answer
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When a tectonic plate subducts, does any of the subducted material melt, or is it just the mantle above the subducted slab that melts?

I know that water released from oceanic crust causes melting of the mantle in subduction zones, but does any part of the subducted slab melt as well - such as the sediments on the slab or the basalt? ...
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3answers
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Why is the elevation of the Iberian Peninsula so high?

The Iberian peninsula lies more than 600 m above sea level, on average, far above similar geological regions in western Europe. Even tectonically undeformed areas in the inner basins present a ...
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2answers
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What is the reasoning behind the statement “Faulting will occur along the plane where the shear stress is the highest”?

In "An Introduction to Seismology, Earthquakes and Earth Structure", authors Seth Stein and Michael Wysession made the statement: "Faulting will occur along the plane where the shear stress is the ...
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2answers
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Predicting earthquakes using disturbances in DTH TV transmission

It is said that before an earthquake happens, a viewer experiences disturbances in DTH TV transmission in the form of distorted images on the screen which automatically correct after a few seconds. ...
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2answers
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What are some of the strongest theories against the existence of mantle plumes?

Among the people I interact with in the geodynamics community, it seems that almost all of us are in full support of the mantle plume theory. What are the strongest arguments against this theory? Is ...
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238 views

How do mantle plumes travel from the core of Earth to the crust?

As mantle plumes begin in the core and move towards the crust, I would have thought that the heat in the mantle plume would disperse to the surrounding mantle, and the plume would cease to exist by ...
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1answer
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Why won't Yellowstone explode?

From my understanding Yellowstone is a massive super-volcano, so why isn't it active? Where has its (correct me if I'm using the wrong term) hot-spot gone? Can it still erupt?
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1answer
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What geological mechanisms result in the great depth of the Mariana Trench?

According to the Mariana Trench Oceanography page is at a maximum depth of is 11,033 meters (36,201 feet) The 'Challenger Deep' being the name of the deepest point. I understand that it is a ...
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1answer
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What are the geological mechanisms for sea floor spreading in the Bismarck Sea?

The North and South Bismarck microplates (north east of Papua New Guinea) are separated by a ridge of sea floor spreading, as described in Oregon State webpage as The tectonics in this part of the ...
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1answer
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What are the implications of the recent discovery that huge oceans exist close to the mantle of the Earth? [duplicate]

I was of the notion that as we get deeper into the Earth, it gets hotter and hotter. If so, how can there be huge oceans (they seem bigger than our Pacific) exist at such a place? If so, what are the ...
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3answers
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Why does Earth's outer-core rotate in the opposite direction to the inner-core?

Is it true that Earth's outercore rotates in the opposite direction to Earth's inner-core? Is there a plausible explanation for why this phenomenon occurs and what is the available evidence ...
11
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1answer
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Why is the Yellowstone National Park unique for its geysers?

The Yellowstone National Park in Wyoming is unique for its large number of "thermal occurrences, of which there are some 30 geysers. This, in turn, appears to be the result of the presence of large ...