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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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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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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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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 ...
personjerry's user avatar
23 votes
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546 views

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 ...
Neo's user avatar
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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 ...
senshin's user avatar
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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 ...
Alistair Riddoch's user avatar
22 votes
1 answer
77k views

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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Plate Tectonics: Is it possible to have an ocean-continent divergent boundary

I am procedurally generating planets for an open world space sandbox game. I am using a rough simulation of tectonic plates to create mountain ranges and other geological features. A planet surface ...
Jacques Nel's user avatar
21 votes
2 answers
2k views

Why does a subduction zone produce a serpentinization diapir rather than volcanism?

The classic Troodos Ophiolite in Cyprus has been uplifted by a 'serpentinization event'. Upper mantle (peridotite) has been serpentinized creating a buoyant diapir. This has uplifted the ocean crust ...
winwaed's user avatar
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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 ...
Kenshin's user avatar
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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 ...
Richard's user avatar
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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.
ceillac's user avatar
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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 ...
senshin's user avatar
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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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18 votes
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Why is there a line of volcanoes along the northwest coast of North America?

Mount Hood in Oregon is a dormant volcano, and in Washington Mount St. Helens and Mt. Ranier are both active volcanoes. What causes this line of volcanoes running parallel to the coastline along the ...
Chris Mueller's user avatar
18 votes
0 answers
229 views

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 ...
N. Virgo's user avatar
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Is there a reason most mountain ranges seem to run parallel to coastlines?

Eyeballing a map of the world, it seems that most mountain ranges that don't occur along continental fault lines run parallel to coastlines. Is there a reason for this?
nmvasq's user avatar
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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!
rnrneverdies's user avatar
16 votes
1 answer
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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? ...
Inkenbrandt's user avatar
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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 ...
Siv's user avatar
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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 ...
Zibbobz's user avatar
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15 votes
3 answers
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What do continents "lay" on?

It's a simple question.. What do continents "lay" on? Do they float on water? or are they huge bodies that "emerge" from the sea floor/bed? are they connected to the bottom of the oceans? Hope the ...
Matan's user avatar
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14 votes
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Is there a geological explanation for the recent Mammoth tusk discovery 185 miles off the California coast?

A recently publicized discovery of a Columbian Mammoth tusk located well of the coast of California in quite deep water made me wonder if geological conditions 100,000 years ago can explain how it got ...
justCal's user avatar
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14 votes
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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 ...
mattdm's user avatar
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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 ...
congusbongus's user avatar
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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: ...
user avatar
13 votes
1 answer
2k views

Why is basalt denser than granite?

If lava is nothing but magma breaking through the earth's surface, then why is basalt more dense than granite? I understand that something happens during the cooling process, but cannot find any ...
Koushik Sarkar's user avatar
13 votes
3 answers
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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, ...
Richard's user avatar
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Why are there no volcanoes where continents collide with each other?

I understand that volcanoes occur where oceanic crust is subducted under continental crust such as the Andes. However, they don't occur at places like the Himalayas and Alps where continental crust is ...
John McCarthy's user avatar
13 votes
1 answer
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Why does the "Ring of Fire" pretty much define "Pacific Rim"

The Pacific Rim is pretty much defined by the so-called "Ring of Fire." It consists of the "stomping ground" for a disproportionate number of earthquakes and volcanoes, and the affected territory ...
Tom Au's user avatar
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13 votes
1 answer
800 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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13 votes
1 answer
962 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 ...
sloopie72's user avatar
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13 votes
4 answers
438 views

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 ...
user2990's user avatar
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12 votes
3 answers
21k views

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
Poomrokc The 3years's user avatar
12 votes
3 answers
10k views

Is the Mid-Atlantic Ridge a ridge or a trench?

I am confused after reading conflicting text from different sources. For example, I read that divergent oceanic plates form ridges. National Geographic calls Mid-Atlantic Ridge a valley! On the other ...
Porcupine's user avatar
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12 votes
4 answers
3k views

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 ...
Neeeedhelp's user avatar
12 votes
1 answer
621 views

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 ...
Kenshin's user avatar
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12 votes
1 answer
221 views

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 ...
user877329's user avatar
11 votes
2 answers
5k views

How could this pyramidal Mountain have been formed?

How could this pyramidal peak have been formed in Antarctica? Little is known about it as far as I know but what is known is that its miles away from any existing plate boundary and its shape is also ...
Charlie's user avatar
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11 votes
2 answers
587 views

Equatorial bulge and tectonic plates

It is well known that the Earth is not a sphere, but rather it bulges at the equator. Also it is well known that the Earth's crust is composed of 7 or 8 (depending on definition) major tectonic plates,...
Kenshin's user avatar
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11 votes
3 answers
29k views

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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11 votes
1 answer
3k views

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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11 votes
1 answer
132 views

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
Fred's user avatar
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11 votes
1 answer
353 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 ...
user590's user avatar
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10 votes
3 answers
2k views

Will the oceans swallow all of the land?

I am wondering why, since the oceans could feasibly hold all of the dry land, they in fact do not. For example, the Mariana Trench drops to -10.9km, while Mount Everest only reaches to +8.8km. ...
Him's user avatar
  • 203
10 votes
3 answers
2k views

Movement of the Prime/Greenwich Meridian

The line on the ground at the Greenwich Observatory is itself on a tectonic plate that is moving, so is the prime meridian still 0 degrees, 0 minutes, 0 seconds? If not - what are the implications (...
GorillaGram's user avatar
10 votes
5 answers
10k views

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?
Joerico's user avatar
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10 votes
1 answer
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Earthquakes at plate boundaries

I was looking into tectonic plate boundaries and earthquakes with pictures like these One thing that is quite obvious is that some of the plate boundaries have very thin zones of earthquakes, ...
M. Kim's user avatar
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10 votes
2 answers
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Do Tectonic Plates Merge?

I had a question concerning the nature of continental plates. When looking at the Eurasian Plate today, for the most part, there is one solid fragment of the Earth's crust. However, having had a look ...
N Francis's user avatar
  • 241
10 votes
1 answer
732 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 ...
Nat's user avatar
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