Questions tagged [tectonics]

Tectonics is the application of field geology, petrology, geochemistry, geochronology, geophysics, remote-sensing, modeling and multidisciplinary studies to explains the evolution, structure, and deformation of Earths lithosphere.

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22
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1answer
522 views

Why are most peninsulas oriented north-south?

Weird question, bear with me. Most large peninsula on Earth are oriented southwards (and most of the rest northwards), much fewer east or west. Some examples: Florida, Californa peninsula, Yucatan, ...
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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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Is there a piece of upside down foreign crust in the USA?

When I studied earth science, a lecturer mentioned that one of the anomalies that earth science hasn’t been able to explain is a piece of crust in the USA. This piece of crust appeared to match very ...
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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: ...
13
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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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How high can a mountain possibly get?

Mount Everest is 8,848 metres (29,028 feet) above sea level and is the result of a continental plate smashing into another continental plate. Can a tectonic process build a mountain that's even higher?...
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Is a San Andreas volcano possible?

This question is, in part, inspired from the 1997 Hollywood movie Volcano, where a fictional volcano erupted out of the La Brea Tar Pits in Los Angeles. The San Andreas Fault is a transform fault ...
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3answers
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Is it known what determines the rate with which plate tectonics occur?

When investigating the rate of the move of the Hawaii hotspot, from information provided here on Stack Exchange Earth Science, I cannot find a determination of cause for the rate, that does not point ...
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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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Do divergent tectonic plates destroy mountains?

Tectonic plates meeting (convergent plates) form mountains. But if those plates change direction (which I am just assuming they can over time, I have no idea if it's true) and start pulling apart (...
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What is the current status of geophysical global cooling theory?

Plate tectonics effectively rubbished the theory of geophysical global cooling as a means of explaining many surface features on the Earth. However, this wiki says that the same process is responsible ...
9
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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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How do tectonics work on other planets?

What kind of tectonic plate activity exists on other planets in the solar system, or even large moons? Are there any deeper studies of what is needed for a planet or large moon to have tectonic ...
8
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Did a crater cause the break up of Gondwanaland & separate Australia from Antarctica

In 2006 it was reported that the Largest Ever Killer Crater was found under ice in Antarctica. Gravity measurements taken by NASA's GRACE satellites indicate the crater is 250 million years old. The ...
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Calculating the displacement of a fault

In the calculation of scalar moment magnitude of an earthquake we have the formula $$M_0=\mu AD$$ where: $\mu$ is the shear modulus of the rocks involved in the earthquake (in Pa) $A$ is the area ...
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Timeline of Himalayas/Tibetan plateau formation

Note: edited based on helpful comments. In Walking with Cavemen, Robert Winston claims an African rainforest existed 8 mya, but by 4 mya it was gone. He attributes this to newly Himalayas-triggered ...
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Explain the Idea of Pangaea and how the continents have reached their current positions

I know Pangaea was a supercontinent that existed 270 million years ago and it started to break apart around 200 million years ago. I'm not clear on whether Pangaea was 1,2, or multiple tectonic plates....
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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.
7
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What is a fault?

Curious if to what degree it is possible to cluster epicentres as originating from a single formation/fault? Seems like it is possible that apart of the issue might being able to map the hypocentre of ...
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Himalayas are currently rising. What will be the highest point they can reach?

Himalayas are currently rising about 5 mm/year. What will be the highest point they can reach?
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Would it be wise to monitor real time human activity to anticipate earthquakes?

Documented strange behaviors of animals before an earthquake could invite us to believe that some of them anticipate tectonic activity. We also know that human complex organization makes it difficult ...
6
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What is the metamorphic field gradient useful for?

As I understand it, the metamorphic field gradient is the PT line traced out by the maximum temperature points of a series of PTt paths of rocks from the same metamorphic event. What exactly is this ...
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What is the tectonic explanation for parallel ridges in the Arctic Ocean?

Looking at a map of the underwater features of the Arctic Ocean reveals three roughly parallel ridges, separated by basins (see image below): Image source The three ridges, as labelled are the Alpha ...
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Resources on Andean geology

I would like to begin studying the geology of the Andes, with particular respect to the tectonics and paleogeography of the region. I have been searching on-line resources for some time and I would ...
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Is “seismic energy released” a regionalized variable and can be analyzed using geostatistics?

In geostatistics, we can assess and analyze regionalized variables. Tectonic stresses releases in seismically active regions by occurring earthquakes. We can calculate and estimate the seismic energy ...
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What is the difference between nappe and thrust sheet?

The titles of many geology articles contain words like "nappes and thrust sheets". Basically these are rather similar and in certain languages can be denoted with one term. The dictionaries tend to ...
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Relationship between tides and earthquakes

Ide et al. (2016) suggest that earthquakes (especially those of high magnitudes) are more probable during periods of high tidal stress (during full and new moons). While they show a comprehensive ...
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2answers
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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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1answer
214 views

Source of sub-surface ringwoodite water

I was reading about the discovery of vast amounts of water locked up in ringwoodite (see here). The authors of the study seem to suggest that previous ideas, involving water deposits being delivered ...
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Do the rocks below an active sill go down, or those above go up, or both?

Having read a little about sill formations like the Palisades Sill (eastern USA) and Whin Sill (UK), I understand that strata became separated by the injected layer of magma, with monumental ...
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What happens to the earth after volcanism/tectonics slows?

If we move far enough into the future that the core begins to solidify to the point that volcanism and tectonics are non-existent, what does the surface of the planet begin to look like? Does the ...
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1answer
361 views

What structures form due to the melting of subducting plates? [closed]

What structures form from the melting of subducting plates? Plutons, Accretionary wedges, Deep sea trenches, Faults?
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1answer
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Is it coincidence that Antarctica is centered on the south pole?

Looking at a globe, Antarctica looks remarkably centered on the south pole. Has the rotation of the earth had any effect on the position of the landmass?
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tectonic faults catalog for plot

I looking for a catalog (ideally in a ASCII file) of the major tectonic faults on earth, in order to plot some of them on a map Any suggestion ?
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For slab rollback, what allows the subducting plate to begin descending at a steeper incline?

I recently learned about slab rollback, specifically of the Juan de Fuca plate subducting underneath the North American plate. From what I understand, the subducting plate over time begins descending ...
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Is the Ethiopian Plateau uplift still ongoing?

The rift zones around the Ethiopian Plateau, Mid Ethiopian Rift, are stil tectonically active since Somalia is separating from Nubia at a rate of 6–7 mm annually[1], and Arabia is rotating counter-...
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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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1answer
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Do earthquakes produce folds on rocks?

Earth rocks are frequently folded at surface. Folds in alternating layers of limestone and chert in Crete, Greece. Source: commons.wikimedia Are earthquakes the main mechanism ...
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1answer
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What is diffuse plate rifting?

For example in the Philippine Sea Plate the West Marianas Ridge has formed due to diffuse rifting in the south of the Marianas trough. What does it mean?
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Determining the spatial orientation of a fault given ground acceleration magnitude in different directions

Accelerographs measure ground acceleration in three different components of motion: east-west, north-south, and vertically (up-down). I know that fault orientation is important here, so let's say we ...
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How do tectonic plates move upward? [closed]

And also, can this push continents and land-masses upward as well?I have not been informed of the phenomenon of tectonic plates rising up. I am yet unable to find a satisfactory answer on the internet,...
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Does being under water provide any protection from a asteroid?

Does being under or on water provide any protection from an asteroid hitting the opposite side of the Earth over being in or on land or in air? Why? Will the shock wave follow the curvature of the ...