Plate tectonics Tectonics is concerned with the processes which control the structure and properties of the Earth's crust, and its evolution through time. In particular, it describes the processes of mountain building, the growth and behavior of the strong, old cores of continents known as cratons, and the ways in which the relatively rigid plates that comprise the Earth's outer shell interact with each other.Tectonics
How does the study of plate tectonics help us to understand earth?
The theory of plate tectonics revolutionized the earth sciences by explaining how the movement of geologic plates causes mountain building, volcanoes, and earthquakes.
How does plate tectonic theory help explain the formation of volcanoes and the cause of their eruptions?
Where plates come into contact, energy is released. Plates sliding past each other cause friction and heat. Subducting plates melt into the mantle, and diverging plates create new crust material. Subducting plates, where one tectonic plate is being driven under another, are associated with volcanoes and earthquakes.
How does plate tectonic help in understanding the geographical distribution of earthquake in the world?
Earthquakes occur along fault lines, cracks in Earth's crust where tectonic plates meet. They occur where plates are subducting, spreading, slipping, or colliding. As the plates grind together, they get stuck and pressure builds up. Finally, the pressure between the plates is so great that they break loose.
How does plate tectonic theory explain the distribution of earthquakes and volcanoes?
Earth's lithosphere is bro- ken into separate sections, or plates. When these plates move around, they collide, move apart, or slide past each other. The movement of these plates can cause vibrations known as earth- quakes and can create conditions that cause volcanoes to form.
What do you think will happen to Earth if tectonic plates are not?
Erosion would continue to wear the mountains down, but with no tectonic activity to refresh them, over a few million years they would erode down to low rolling hills. So the whole planet would be flatter, and the topography would be a heck of a lot less exciting. You'd probably be less inclined to go trekking in Nepal.
What is the effect of tectonic plate movement?
The uplift and sinking of land, earthquakes (the sudden release of energy that causes shaking), and volcanic eruptions are all evidence of interactions and stress due to the movement of the plates.
What are tectonic plates and discuss their distribution?
Tectonic plates are gigantic pieces of the Earth's crust and uppermost mantle. They are made up of oceanic crust and continental crust. Earthquakes occur around mid-ocean ridges and the large faults which mark the edges of the plates.
How does plate tectonics explain the distribution of mountain ranges?
Mountains form where two continental plates collide. Since both plates have a similar thickness and weight, neither one will sink under the other. Instead, they crumple and fold until the rocks are forced up to form a mountain range. As the plates continue to collide, mountains will get taller and taller.
In what way is the plate tectonic theory helpful in explaining the occurrence of volcanoes and earthquake epicenters?
As plates move, they get stuck in places, and enormous amounts of energy build up. When the plates finally get unstuck and move past each other, the energy is released in the form of earthquakes. Earthquakes and volcanoes are common features along tectonic plate boundaries, making these zones geologically very active.
How are volcanoes formed by plate tectonics?
At constructive plate boundaries, the tectonic plates are moving away from one another. The Earth's crust is pulled apart to create a new pathway for rising hot magma to flow on to the surface. Volcanoes can sometimes form in these setting; one example is Iceland.
Does the theory of plate tectonics explain where volcanoes are located?
The theory of plate tectonics explains most of the features of Earth's surface. It explains why earthquakes, volcanoes, and mountain ranges are where they are. It explains where to find some mineral resources.
Which tectonic plate movement creates volcanoes?
The two types of plate boundaries that are most likely to produce volcanic activity are divergent plate boundaries and convergent plate boundaries.
In what way is the plate tectonic theory helpful in explaining the occurrence of volcanoes and earthquake epicenters?
As plates move, they get stuck in places, and enormous amounts of energy build up. When the plates finally get unstuck and move past each other, the energy is released in the form of earthquakes. Earthquakes and volcanoes are common features along tectonic plate boundaries, making these zones geologically very active.
What tectonic plate movement causes volcanoes?
Destructive, or convergent, plate boundaries are where the tectonic plates are moving towards each other. Volcanoes form here in two settings where either oceanic plate descends below another oceanic plate or an oceanic plate descends below a continental plate.
What causes volcanoes to erupt?
Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber.
How does the plate tectonic theory explain the formation of islands in the Pacific region?
As a crustal tectonic plates move over hot spots mantle material upwells and erupts on the surface of the plate to form a volcano, seamount or volcanic island. The islands and seamounts of the Hawaiian Archipelago were created by a hot spot under the Pacific Plate that has been active for the past 41 million years.
What is plate tectonics?
The plate tectonic theory is the theory that describes large amounts of movements in the Earths lithosphere, whereby Continental and Oceanic crust is moved, destroyed and made from this. The idea of plate tectonics builds on other concepts such as continental drift, where continental plates over millions of years move, however the concept of continental drift was not accepted for some time, and there were many other theories to suggest that something else took place, as the idea of the earth moving….
How does plate tectonics help us understand the distribution of earthquakes and volcanoes?
Plate tectonics can help us understand the distribution of earthquakes and volcanoes very easily, it is recorded that main earthquake and volcanic zones are clustered along plate boundaries and more powerful ones are near destructive and conservative plate boundaries. Over time we have learnt that earthquakes that occur on a constructive plate boundary cause little hazard to….
What happens when the continental plate meets the oceanic plate?
When an oceanic crust meets a continental crust, the denser oceanic crust is forced under the continental plate and melts due to friction and high pressure in the subduction zone. The pressure builds up and is released suddenly, creating earthquakes. Subsequently, the continental plate is crumpled by the pressure and fold mountains are formed. An example of a fold mountain is the Andes.
What happens when two oceanic plates converge?
When two oceanic plates converge, one is usually subducted under another and a deep oceanic trench is formed. The Marianas Trench, for example, is a deep ocean trench created as a result of the Phillipine plate subducting under the Pacific plate.
What is conservative plate margin?
At a conservative plate margin, one plate moves past another.
How many plates are there on Earth?
The Earth’s crust is made up of seven major plates and several smaller plates. These plates drift on top of the mantle. When two plates meet, they can either be constructive, destructive or conservative.
Which islands are evidence of the plate tectonic theory of hot spots?
The Hawaiian islands are evidence of the plate tectonic theory of hot spots. To the west and to the north of
What are the continents?
The continents are blocks of thick crust that are passengers on the tops of large tectonic plates (lithosphere) that move over a softer part of Earth’s mantle (asthenosphere). Earthquakes, mountain building and volcanic activity occur mostly at the boundaries of the moving plates.
How many major plates are there on Earth?
Below is a map of the tectonic plates of the earth. The Earth has a dozen or so major plates and several minor plates.
How has plate tectonics revolutionized geology?
Plate tectonics has revolutionized the way we view large features on the surface of the Earth. Earth’s internal processes were previously thought to operate in a vertical fashion, with continents, oceans, and mountain ranges bobbing up and down, without much sideways movement. But the acceptance of continental drift and other evidence for large lateral motions changed all that. Now it’s understood that Earth’s internal processes can move large plates of Earth’s outer shell great horizontal distances. Plate tectonics thus provides “the big picture” of geology; it explains how mountain ranges, earthquakes, volcanoes, shorelines, and other features tend to form where the moving plates interact along their boundaries.
What is the supercontinent that is made of thick crust?
Blocks of thick continental crust fit together nicely along the edges of their shelves to form the supercontinent called Pangea.
What are the three observations of earthquakes?
First, earthquakes are not scattered throughout the oceans, but instead are confined to narrow, rather continuous bands. The narrow zones of earthquakes outline the boundaries of moving plates.
What is the big picture of tectonics?
Plate tectonics thus provides “the big picture” of geology; it explains how mountain ranges, earthquakes, volcanoes, shorelines, and other features tend to form where the moving plates interact along their boundaries.
How deep do seismic waves travel?
Finally, seismic waves slow down as they travel through a zone about 100 to 400 miles (150 to 700 kilometers) deep, a sign that there is a relatively soft layer within Earth’s mantle. This last observation is the “Rosetta Stone” for plate tectonic theory. It provides a means by which continents can drift apart.
What happens when two plates move in the same direction?
Conservative plate margins occur when two plates are sliding past one another parallel or nearly parallel, they may be moving in the same direction with different speeds or different directions. Here no crust is destroyed or split apart and so there is no upwelling of magma from the mantle – hence earthquake but the absence of volcanism. But the friction from sliding or locking and breaking free of the plates results in the release of energy in the form of earthquakes such as the San Andreas Fault in California and the Alpine Fault in New Zealand. However, the movement of plate tectonics fails to explain several different observed phenomena, including the intra-plate volcanic activity of Hawaii and Yellowstone National Park.
What are the two forms of plate boundaries?
Constructive plate boundaries come in two forms; oceanic ridges and rift valleys. At oceanic, the oceanic crust is created where the mantle convection spreads the sea floor, this creates areas of low pressure and the plastic mantle forms a mafic (which is rich and magnesium and iron) that effuses onto the sea floor.
What are hot spots in the mantle?
John Tuzo Wilson offered an explanation by putting forward the existence of ‘hot spots’. These are broad dome of magma up to 1,000km across within the mantle that may generate result in magma breaking to the surface through fissures and cracks. The old explanation for these is superheating at the core-mantle boundary generating a more powerful convection current which becomes molten in the lower pressure of the upper mantle. But recent evidence has not tallied up with this deep-rooted explanation. Alternative suggestions say that the movements of crustal plates create areas of low pressure over the plastic mantle, or possible that ancient, partially melted subducted oceanic slabs turns molten in low pressure. These would rise as a much shallower plume no deeper than 400-600km.
Why do mountains rise up when two continental plates are pushed together?
When two continental plates are pushed together across a shrinking ocean, the crust is too buoyant to be subducted and so they rise up into mountains. Here there is no volcanic activity because magma is unable to move up through any cracks, and the mountains may include marine geology such as limestone or fossils.
Where does the oceanic crust sink?
Here denser oceanic crust sinks beneath the light continental plate into the upper mantle where the intense heat melts it down into an andestic magma. The collision produces a deep sea trench and often a fold mountain range, and the angle at which the crust subducts may change the characteristics of the area.
What are some examples of volcanic eruptions?
Classic examples include the Mt. St. Helens eruption of 1980, where the active stratovolcano is part of the Ring of Fire and erupted as the most economically damaging volcanic event in US history. Also the Mt. Pinatubo eruption in 1991 in the Philippines, which was the 2nd largest terrestrial explosion of the century, ranked at level 6 on the Volcanic Explosivity Index. Seismic examples include the Japanese earthquake of 2011, a magnitude 9.0 undersea mega-thrust, being the most powerful earthquake to ever hit Japan and the 5th most powerful ever recorded. The 6th largest ever recorded was the Chilean earthquake of 2010 where the 8.8 earthquake struck along a 700km, and was felt by 80% of the population of the country.
What is plate tectonics?
Plate tectonics is the theory used to explain the structure of the Earth’s crust and many of the associated phenomenon. The rigid lithosphere is split into 15 major plates that slowly move on top of the underlying asthenosphere (plastic upper mantle), and this science studies the faulting and folding of the crust along the various boundaries: ...