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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1 answer
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How Do Plateaus Really Form?

Any time I hear the word "plateau", I usually associate it with the tallest in the world, Tibet. Anyone who looks closely at a map will see that the southern line of the plateau parallels the ...
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Is the Pacific Plate composed of smaller plates?

The question, Why are all lower mantle plumes under oceans? has the following diagram which was taken from Wikipedia Commons. About half of the large red dots occur on or near the boundaries of ...
4 votes
1 answer
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Is it inaccurate to describe Earth's mantle as "soft and plastic"?

The Earth's mantle, away from the occasional magma chamber, is solid. But it flows over time and so is described as "pliant", "hot chocolate", "toothpaste", etc. Glaciers ...
2 votes
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What is the maximum intensity with which an earthquake can struck Chitral city in Northern Pakistan?

I am working on a disaster response logistics case study in which I am using Mi-17 helicopters for transportation of relief to the affected areas in main Chitral city. In this regard, I want to ...
3 votes
1 answer
426 views

Do subducted continents rise up again through ridges?

Layman here, sorry if this is a stupid question. I have a geology friend who recently told me that plate tectonics is like how warm milk cools on top to form thin solid layers. The convection cells in ...
3 votes
2 answers
106 views

Do tidal forces affect subduction?

I know subduction in plate tectonics is mainly density driven. Probably a hypothetical question, but can weaknesses caused by tidal forces have an influence on the start of a subduction zone? Would ...
2 votes
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Is the earth crust under the pacific ocean heavier than in the rest of the planet?

Please bear with me, since I don't know much about geography or geology. I was looking at an earth globe and noticed the pacific ocean covers virtually half of the planet (more or less). How is it ...
5 votes
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Farallon plate subducting under North American plate: is it a factor in "the next big one"?

I am a writer, not a scientist of any kind. I live in the SW AZ desert (USA), so we get earthquakes from time to time. I grew up in southern CA, right next to the San Andreas fault, so I have a ...
4 votes
2 answers
108 views

What forces plays the role in order to subduct the denser tectonic plate under the lighter plate?

I am a 10th grade student and I don't know much about geology but I'm learning about subduction online. It's always mentioned that the denser plate gets subducted under the lesser denser plate. I want ...
11 votes
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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, ...
26 votes
5 answers
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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 ...
3 votes
2 answers
542 views

If among oceanic crusts older means heavier, then why is old continental crust lighter than new oceanic crusts?

When we consider two oceanic crusts, the older oceanic crust is heavier and the newer oceanic crust is lighter. But when we consider two crusts, one continental and the other oceanic, continental ...
12 votes
1 answer
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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 ...
6 votes
1 answer
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Do these rock layers correspond to different years?

This is a close picture of a cliff in the north coast of Spain. As you can see, the rock is composed of multiple thin layers, alternating between dark and light materials. Could this be the result of ...
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Is the Theia impact partly responsible for the distribution of mantle plumes?

I was looking at a map of the distribution of mantle plumes, and was wondering if they could be residual material that was either brought here or affected by the Theia impact. It seems to me that this ...
2 votes
1 answer
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Can a tectonic plate subduct under one plate while another plate subducts under it along the same boundary?

At a triple junction plate boundary there are three tectonic plates meeting. We have plenty of examples of these boundaries on Earth, notably the Afar Triple Junction, Mendocino Triple Junction, and ...
5 votes
2 answers
287 views

How is felsic magma produced at island arcs?

I previously believed that continental crust owes its lower density to the partial melting of oceanic crust; the mantle would partially melt at mid-ocean ridges to produce basaltic crust, and when ...
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Google Earth type, online plate-techtonics demonstration over time

I once found an site on the internet that displayed the continents in a Google Earth type setting where you could spin, zoom and navigate around the Earth but in different geological time periods. You ...
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1 answer
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Speculative Plate Techtonics - Resolving intersecting subductions

I'm working through Artifaxian's (https://www.youtube.com/watch?v=AzD_WVsEIRM) series on using gPlates to make tectonic history. I've run into the place where I have two subduction ridges about to ...
8 votes
1 answer
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Does the Moon affect earthquakes?

Does the Moon, through factors like its location (if it is at an apsis i.e closest point or furthest point in its orbit) or some changes in density, affect earthquakes on the Earth? Earthquakes are a ...
21 votes
2 answers
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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 ...
3 votes
2 answers
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Why are the supposed-to-be results of collision and/or subduction formed in an area where collision and/or subduction didn't happen?

Please correct me if I have said something wrong, as it might be the answer to my question. Also, these are all the things that I've learned through self-studying, so I might have been mislead. ...
7 votes
2 answers
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Would the US East Coast rise if everyone living there moved away?

I watched a documentary about research on the coasts of Greenland where the sea level has fallen. According to the research, this is because a lot of the glaciers have melted, resulting in less weight ...
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Least equatorial ( and tidal) bulge consistent with modest amounts of water in polar regions

In World Building I asked a question about the climate of an hypothetical planet. There Vogon poet said that Everyone above 10° latitude will be in permanent drought Considering that there were no ...
3 votes
2 answers
179 views

Why aren't there ultra acid igneous rocks?

In my study, I found that in volcanoes when the magma is going up it formed different types of rocks. There are basic, acidic and ultrabasic. My question is why isn't there ultra acid igneous rocks ...
4 votes
1 answer
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Origin of the continents

Visiting from WorldBuilding SE. Someone recently asked a question that dusted off an old theory I had once had, so I started digging. Sadly I could find little more on the topic than the first time I ...
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Would obliquity and precessional changes of Earth affect the accuracy of GPS-based measurement of tectonic movements?

The rate and direction of tectonic movements can be measured by comparing the coordinates of the same GPS receiver over time. The coordinates are obtained using trilateration. All materials I could ...
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Does the Plate tectonics contradict the theory of continental drift?

According to the theory of continental drift, South America and Africa was so closed to each other that the convex triangle of South America meets the concave hollow of Africa. Source: usgs.gov; ...
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4 answers
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How do tightly packed plates move in the theory of plate tectonics?

Here are two questions I had ever since I first heard about plate-tectonics. How can the plates move? Before you suggest me some page to read about plate movement mechanics, let me clarify that I am ...
3 votes
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Is there any research on the relation of asteroid impacts and hot-spots?

In a new video by Atlas Pro on Hawaii linked below, he indicates a curious observation: Most hotspots antipode’s have sign’s of heavy impacts from asteroids. He postulated that the force of these ...
2 votes
2 answers
361 views

Are oceanic plates or continental plates heavier?

If you take a cilindrical section with radius 1 meter of both kinds of plate, which will have a larger mass? My guess is that continental plates are heavier than oceanic plates, because they are more ...
4 votes
2 answers
431 views

Why aren't the Hawaiian islands a continuous strip of land?

My understanding is that the Hawaiian islands were produced as the Pacific plate moved over a stationary hot spot, which sent magma burning up through the plate as it passed over, forming a trail of ...
5 votes
1 answer
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Why does the ocean floor look so scratchy?

Why does some part of the ocean floor look so scratchy? If you look at Google Earth image of the Indian ocean floor, especially the area south-west of Sumatra, it looks like some cosmic beast ...
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What is causing the crustal extension exhibited by the Basin and Range province in western North America?

Is there any link with the subduction of the Farallon Plate and the associated spreading center?
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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 ...
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Why is the Colorado Plateau so stable?

The Colorado Plateau somehow has avoided all the tectonic activity around it over hundreds of millions of years. Is it just luck, or is there something about that chunk of crust? I have toured the ...
3 votes
2 answers
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Can continental plates collide and fuse together without an orogenic band or magmatic arc or at the junction?

I have seen this diagram on Wikipedia (link below). It shows that some North American mini-plate boundaries are orogenic bands and some are magmatic arcs, and I think those correspond to continent/...
5 votes
2 answers
544 views

How likely are caverns inside the mantle?

Almost everyone wrongly assumes that the Earth's mantle is liquid, but it isn't (only the outer core is). Is it possible then that there are hollow spaces within the mantle, similar to caves in the ...
5 votes
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Difference between Ocean-Ocean subduction and Continental-Ocean from earthquake data

I am having a hard time finding this anywhere -- if no one can answer, I would appreciate a reference. I was doing introductory homework in earth science, and we had to determine the kind of plate ...
14 votes
1 answer
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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 ...
2 votes
1 answer
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What role does the hydrosphere play in tectonic plate convection?

I need to do a "how do different 'Earth's spheres' interact with each other" and I'm trying to figure out how the hydrosphere would affect the lithosphere if the ozone layer were to ...
1 vote
4 answers
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Can garbage be sent into the (near-)center of the world?

I've been thinking about how difficult it is to eliminate toxic chemical waste -- it usually needs high temperatures and pressures. So: would it be feasible (and maybe cheaper) to send it into the ...
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What is the consensus among geologists about climate change being caused by humans?

I'm terribly frustrated with the way that climate change has been debated in Europe. I live in the Netherlands and members of one of the biggest parties here, the Party for Freedom (PVV), frequently ...
3 votes
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When did the proto-Himalayas become non-volcanic?

In the normal course of events, when continents move toward each other, at least one coast will be associated with a subduction zone and corresponding volcanic activity. When the Indian subcontinent ...
2 votes
1 answer
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Tectonic plates terminology

I have a very basic doubt regarding what the tectonic plates mean. In Wiki article Subduction is defined as: Subduction is a geological process in which the oceanic lithosphere is recycled into the ...
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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.
8 votes
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Cause of Wallace line

First off, I am a biologist, not an earth scientist. Very recently I heard about a very interesting biological phenomenon that has its origins rooted in geology : The Wallace Line. From a ...
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1k views

Why do some earthquakes and volcanoes occur within plates?

I know that volcanoes and earthquakes occur on plate margins. But, do some of them also occur within plates?
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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 ...
12 votes
3 answers
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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 ...

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