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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35 votes
4 answers

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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26 votes
7 answers

Could the Earth's core lose its heat?

Will all the drilling and digging to use the Earth's natural heat as geothermal energy affect the Earth's core, causing it to cool down? If so, would it result in an ice age? If not, how does the ...
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14 votes
1 answer

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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16 votes
2 answers

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 ...
12 votes
3 answers

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 ...
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11 votes
2 answers

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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4 votes
1 answer

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 ...
16 votes
1 answer

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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16 votes
6 answers

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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9 votes
2 answers

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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8 votes
3 answers

Gaps in locations of volcanos (Peru & Chile)

The figure below is taken from Reath, K. et al. (2019) A couple of things can be seen from this representation Volcanism seems to be strongly correlated with subduction zones, in this case the Nazca ...
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8 votes
1 answer

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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7 votes
5 answers

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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