Tectonics Flashcards

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1
Q

Crust

A

It is the outer layer of the Earth. It varies from 5 - 70 km thick. The oceanic crust is thinner and denser than the continental crust. It has an average temperature of about 750℃.

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2
Q

Lithosphere

A

A combination of the lower crust and upper mantle. This area is notable, as it is split into tectonic plates.

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3
Q

Asthenosphere

A

The point where the mantle becomes more fluid and it flows more easily. It is below the Lithosphere.

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4
Q

Mesosphere

A

The lower part of the mantle. The pressures start to get higher, causing it to be slightly more solid.

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5
Q

Mantle

A

About 2,900 km thick and contains 84% of the earth.

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6
Q

Outer Core

A

It is beneath the mesosphere and it is completely liquid. It has temperatures of about 6,100℃ and it is 2,200 km thick. Currents in it creates Earth’s magnetic field.

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7
Q

Inner Core

A

About 1,400km thick. It is solid due to the incredible pressure, and it is the same temperature as the outer core.

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8
Q

Convection Currents

A

Material in the Mesosphere heats up and rises. When this material hits the lithosphere it exerts pressure on it and drags the plates apart. This causes geological activity. Eventually, the material cools and sinks, to restart the process.

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9
Q

How is a volcano created?

A

When convection currents cause tectonic plates to pull apart, magma rises and fills this gap. This magma eventually solidifies into rock, but occasionally, lava breaks through in an eruption. This causes rock to settle in the form of a peak.

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10
Q

How does an Earthquake occur?

A

On the boundaries of Tectonic plates friction can occur as the plates rub against each other. This is called an earthquake.

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11
Q

What is a plate boundary?

A

Where two plates join.

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12
Q

What is a Divergent/Constructive plate boundary?

A

When two tectonic plates are drifting apart. This causes a gap to appear which magma fills. The magma then solidifies, which means that often volcanoes occur on these boundaries. Volcanic activity is generally quite gentle, and no friction means no earthquakes.

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13
Q

What is a Convergent/Destructive plate boundary?

A

When one continental and one oceanic, or two oceanic plates collide, the denser of the two slides (subducts) under the other. This causes large amounts of friction, which causes Earthquakes. As one of the plates sinks, it melts, exerting pressure on the crust. Magma can then burst through, causing explosive volcanic activity.

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14
Q

What is a Collision plate boundary?

A

When two continental plates collide into each other. Neither plate is dense enough to sink, so instead, ripples form in the crust when the plates push against each other. These ripples are mountains. There are also small amounts of friction. This means that mior earthquakes can occur.

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15
Q

What is a Conservative plate boundary?

A

This occurs when two plates are moving side by side, but at different speeds or in different directions. This causes large amount of friction, which means that Earthquakes are common on these boundaries.

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16
Q

What are some characteristics of a Composite volcano?

A

It has acidic, thick lava. This means that the lava doesn’t flow very far before it evaporates, meaning the sides of these volcanoes are very steep. The eruptions tend to be less frequent, but when they occur, they are very powerful. They have alternating layers of ash and lava.

17
Q

What are some characteristics of a Shield volcano?

A

It has basic, runny lava. This means that the lava flows far before it solidifies leaving a gentle wide slope. The eruptions tend to be more frequent, but less powerful that Composite volcanoes. They are made of solid lava.

18
Q

What is Hotspot theory?

A

It is the theory that through the mantle, there are hot, rising plumes of rock, and that when they hit the crust, they pierce through it, but only on an oceanic crust due to its thickness. It then forms a volcano which goes extinct when the crust passes over it. It then creates another volcano, eventually creating lots of volcanic islands.

19
Q

What is the Focus of an Earthquake?

A

Where the friction and pressure is released.

20
Q

Where is the Epicentre of an Earthquake?

A

The point directly above the focus on the crust.

21
Q

What are Seismic Waves?

A

They a waves of energy that travel through Earth’s layers and are a result of earthquakes.

22
Q

What is a Fault?

A

A plate boundary.