Questions tagged [plate-tectonics]

The theory that Earth's outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core.

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10
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1answer
664 views

How deep are the cracks in the earths crust at fault zones?

I have seen pictures of the cracks in the Earth's crust in Iceland and the San Andreas fault. To my eyes, the crack is relatively wide at the surface than a few meters down seems to be very narrow or ...
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453 views

How is/was continental drift monitored?

I am curious about current technology but I am particularly interested in what techniques were employed prior to the advent of satellite technology.
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114 views

Could the magnetic field influence tectonic forces

Paleomagnetism can be measured as the magnetic field at the time of rock forming is preserved in some minerals. Could the paleomagnetism and the present magnetic field somehow influence the movements ...
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4answers
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Can an earthquake occurring within two plates trigger another earthquake in a far away plate boundary?

Can an earthquake occurring between two plates, like the Pacific Plate and North American Plate cause any effect which would trigger an earthquake in a far away place like the boundary between the ...
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Why is continental crust less dense than oceanic?

Why is it that continental crust is less dense than oceanic, where in fact continental crust is thicker than oceanic crust?
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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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Will a nuclear bomb stop an earthquake from happening?

I was recently watching the San Andreas trailer and a thought occurred to me as to how best to prevent earthquakes. I figured, why not nuke it? My professor said that it's possible for nukes to stop ...
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(Why) Is there more landmass on Earth's Northern hemisphere than the Southern Hemisphere?

This Question on Worldbuilding is based on the presumption that there is a greater amount of landmass on the Earth's Northern Hemisphere than there is on the Southern Hemisphere. While researching ...
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3answers
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Is continental drift caused by lava pushing the seabed apart?

My daughter has a writing assignment based on a handout about plate tectonics. One paragraph says: Molten rock from the earth's mantle pushes up through the surface at the mid-Atlanic ridge. The ...
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1answer
339 views

Is Iceland an example of a hot-spot overlying a mantle plume?

Iceland has been cited as the location of a hot-spot overlying a mantle plume (similar to that of the Hawaii chain in the Pacific), though for some time this model has been challenged (see Gillian ...
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Why does sea level correspond to boundary between oceanic and continental crust?

Is it a coincidence? the first is determined by the amount of water on the Earth and the second comes from evolution of tectonic plates. Still, oceans seem to fill exactly the oceanic crust.
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Why was the initial theory of plate tectonics so controversial?

I have been set the task of researching plate tectonics, specifically: "Why was its discovery so important in its time and controversial?" I do not need a long answer, although more detail is always ...
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1answer
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Why is there a bend in the Lomonosov Ridge?

Why is there a bend in the Lomonosov Ridge? This is a supplementary question to that asked by Sabre Tooth in What is the tectonic explanation for parallel ridges in the Arctic ocean
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1answer
727 views

Active rifting in Antarctica?

The West Antarctic Rift exists between the Trans-Antarctic Mountains and Marie Byrd Land (see map below for reference) Image source: NASA The rift system is believed to be like the East African Rift,...
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What does the absence of passive margins between 1740-1600 million years ago tell us about the tectonic environment at that time?

In the article Passive margins through earth history (Bradley, 2008), a passive margin is defined as: a synonym for the bulkier Atlantic-type margin, trailing-edge margin, rifted margin, or ...
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2answers
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What is the tectonic setting for the formation of the Great Dividing Range in Australia?

Australia's Great Dividing Range is the largest mountain range on the continent, running down the length of the eastern part of the continent, as shown in the Geoscience Australia map as a dark line, ...
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What do the derivative or the integral of amplitude of a seismogram mean?

I'm doing a project in which I'm analyzing earthquake seismogram waves. I used a program to graph the exact amplitudes and how they changed over the course of a single earthquake. For the project I ...
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1answer
873 views

What tectonic structures delineate the split between the Australian and Indian tectonic plates?

Growing up, when looking in textbooks and other references about plate tectonics, there was always the Indo-Australian (or Indian-Australian) plate, such as shown below: Image source: The Geologic ...
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1answer
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What tectonic structures exist on the Eurasian - North American plate boundary in eastern Siberia?

It is reasonably well known that the North American tectonic plate includes a portion of eastern Siberia. What is often typical in plate tectonic maps is that the actual plate boundary is often drawn ...
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1answer
742 views

What is the definition of a continent?

Is there a scientific definition of a continent? Is there an academic reference for such a definition? There's a tendency to correlate with tectonic plates, but of course lots of plates don't have ...
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477 views

Is the Cameroon Line still an active rift zone?

The Cameroon Line is described by the Oregon State University's Volcano World webpage What is known about the volcanoes of Cameroon? as a a chain of volcanoes extending from Annobon Island in the ...
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What are the tectonic implications of the Quaternary Igwisi Hills, Tanzania, kimberlite volcanics?

The Igwisi Hills Kimberlite volcanic features in Tanzania are described in the article Mapping the Igwisi Hills kimberlite volcanoes, Tanzania: understanding how deep-sourced mantle magmas behave at ...
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3answers
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Does the climate have any effect on plate tectonics?

After reading the question and answer Is there any correlation between La Niña/El Niño and seismic activity?, I am wondering if there is any evidence (case studies) to suggest that longer term ...
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Has an entire plate ever subducted?

We know that plates can subduct, causing one plate to be pushed into the core by another. As the plates move, the subduction continues, pushing one plate under the other. If this process continues, ...
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What geological processes would 'restart' subduction processes?

According to the Science Daily article Plate Tectonics May Grind To A Halt, Then Start Again (Carnegie Institution), one main aspect of the research being presented is the hypothesis that suggests ...
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At what point does plate tectonics stop?

As the core and mantle of the earth cools, it will reach a point where new crust cannot be produced. How can this point be calculated? If we can, has anyone done such calculations? Thanks!
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Is there evidence to delineate where a southern extension of the East African Rift 'plate boundary' is developing?

The East African Rift system is described by James Wood and Alex Guth of Michigan Technological University in the Geology.com web-article East Africa's Great Rift Valley: A Complex Rift System as ...
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1answer
684 views

What evidence is there linking melting ice caps and changes in tectonic movement?

Reading one of my other questions, How much would the Greenland landmass isostatic rebound contribute to long term climate change?, a subsequent question is what, if any, effect the isostatic rebound ...
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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 tectonic mechanisms cause the North and South Islands of New Zealand to be so geologically different?

New Zealand is a very active seismic and volcanic region of the Pacific Ring of Fire, on the boundary of the Australian and Pacific Plates; however, there is a difference between the 2 islands: ...
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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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What caused the bend in the Emperor/Hawaii chain of islands, 45 million years ago?

What caused the bend in the Emperor/Hawaii chain of islands, 45 million years ago? Has there been any updates to this mystery I am unaware of? Are there any new theories that could potentially ...
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During the "Ice Ages" or "Snowball Earth" times, where was all the energy?

We often seem to accept the idea that there were periods of time in which the entire surface of Earth was frozen, for the most part. This implies that there were periods of time in which the entire ...
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396 views

Why do Euler poles for plate motions not stay fixed in time?

Surely if a plate motion is a straight line across a sphere, this can be described by a fixed Euler pole, however I've been reading about a problem which I confess I don't fully understand which is ...
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1answer
191 views

Geometrical differences of subduction zones

I am looking for geometrical differences in subduction zones. What are the differences, in dip, curvature of the interface, thickness of the plates etc.? There are differences between the Chile and ...
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1answer
342 views

Relation between fault rupture aspect ratio and slip rate?

I am modeling a fault surface (which I consider to be a plane rectangle). I got the area of the surface, but the orientation is unknown, which can be found out if the aspect ratio of the rectangle is ...
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1answer
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Can Venus be considered to be tectonically active?

Venus is noted for its absence of spreading ridges, transform faults, and subduction zones, which are characteristic of plate tectonics on Earth. But given that it exhibits rift zones, mountain belts ...
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Probability distribution of fault throw displacement and height limiting mechanisms

First, what is the probability distribution of fault throw displacement. Uniform distribution seems unlikely, since then small changes would add up to huge huge elevation differences that require a ...
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673 views

Why is the Ring of Fire there? [duplicate]

The Ring of Fire goes through the places that have the most earthquakes. Why is the Ring of Fire there, not somewhere else? Any help would be appreciated!
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What properties must a rocky body possess in order to exhibit plate tectonics?

The Earth exhibits plate tectonics, but the other terrestrial planets do not (though Mars and Venus may have exhibited plate tectonics in the past). What is "special" about Earth that allows it to ...
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Historically, how has the fraction of Earth covered by water changed?

Today, 70.8% of the Earth is covered in water (± a few tenths of a percent depending on how you account for lakes).1 How has this figure changed over the history of the Earth, and why? Of course, if ...
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1answer
361 views

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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How would plate tectonics differ if Earth had no water?

Water plays a crucial role in plate tectonics by easing the brittle and ductile deformation of the Earth's lithosphere. Water lowers the Mohr-Coulomb for brittle fractures. During ductile deformation, ...
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Is Mount Everest currently becoming taller or shorter every year?

Is Mount Everest becoming taller or shorter every year? By how much? I would like an explanation in terms of tectonic plate movement if possible. Source: IamKatieHoffman.com
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What causes intra-plate faults, such as the New Madrid fault?

There's been news (some recently) about the New Madrid fault and other active intra-plate faults. For those living in the midwest of the United States, it's been a bit of a shock to learn they have ...
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1answer
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Are mantle plumes distributed around the core randomly or in a known pattern?

Background: The theory of mantle plumes is useful (although controversial) in explaining the occurrence of intra-plate volcanoes. The website here suggests that "hotspots" exist in fixed locations ...
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How much heat is transported from the interior to the surface in the form of hydration enthalpy?

Heat is transferred from the interior to the surface through several methods. One is simply the conduction of sensible heat through the crust - I would guess this accounts for most of it. But some is ...
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1answer
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Why are oceanic plates denser than continental plates?

In the theory of tectonic plates, at a convergent boundary between a continental plate and an oceanic plate, the denser plate usually subducts underneath the less dense plate. It is well known that ...
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3answers
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How did Earth's plate tectonics start?

Plate tectonics is a theory which describes Earth's lithosphere as being composed of distinct plates which are able to move atop of the underlying asthenosphere. At plate boundaries, this movement ...
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1answer
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Why do tectonic plates have a tendency to drift closer to the equator?

There are many factors that drive the movement of tectonic plates on the surface of asthenosphere, and some of these factors have a larger contribution than others (e.g. slab suction). One driving ...