Chapters 5, 6, 7 Flashcards

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0
Q

Describe the three types of faults.

A

Normal fault – two plates are diverging, the foot wall is above the hanging wall.
Reverse Fault- two plates are converging, the hanging wall is above the foot wall.
Strike-slip fault – two plates slip past each other.

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1
Q

Describe the three types of stress that can cause faults.

A

Tension- pulls out until it is thin in the middle.
Compression- squeezes until folds or breaks.
Shearing- slips past each other.

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2
Q

Describe the speed and types of motion for P waves, S waves, and surface waves.

A

P waves – compresses and expands the ground like an accordion, fastest wave. ⬅️➡️ ➡️⬅️
S waves – vibrates from side to side or up and down, slower than P waves but faster than surface waves. ⬆️⬇️⬅️➡️
Surface waves – P or S waves that come to the surface, creates the most damage, the slowest wave. ↪️↩️

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3
Q

P waves, S waves, and surface waves are known as _________ waves.

A

seismic

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4
Q

Ranks the amount of shaking from an earthquake, 12 ranks.

A

Modified Mercalli scale

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5
Q

Estimates and rates the total energy an earthquake releases, gives magnitude. We use today, 0–9.5 (as high as it needs to go)

A

Moment Magnitude scale

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6
Q

Rates the magnitude of small earthquakes based on the size of the earthquake’s waves as recorded by seismographs, earliest scale used, outdated.

A

Richter scale

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7
Q

Seismograph data shows that earthquakes often occur _________.

A

Along plate boundaries

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8
Q

According to Wegener’s hypothesis of continental drift…..

A

All the continents were single together and in one continent called Pangea.

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9
Q

What technology was used in the mid- 1900s to map the mid-ocean ridge?

A

Sonar

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10
Q

Where and how does seafloor spreading occur?

A

When molten material erupts, cools, and hardens to form a solid strip of rock. Occurs along mid-ocean ridges and deep-ocean trenches.

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11
Q

Mid ocean ridges form the ___________ mountain ranges on Earth.

A

Largest

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12
Q

In which location would you most likely find volcanoes?

A

Along the mid-ocean ridge and a plate subducting under another.

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13
Q

What is the main factor that determines if a volcanic eruption will be quiet or explosive?

A

This silica content

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14
Q

What force causes magma to erupt to the surface?

A

Dissolved gases that are trapped and create pressure.

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15
Q

If geologists detect many small earthquakes in an area near a volcano, they can infer…

A

That the volcano is about to erupt.

16
Q

Oceanic crust near the mid-ocean ridge is _________ than oceanic crust farther away from the ridge.

A

Younger

17
Q

If subduction occurs at a slower rate than oceanic crust can be created, the ocean will _________.

A

Expand

18
Q

A major volcanic belt known as the ______________ circles the Pacific Ocean.

A

Ring of Fire

19
Q

Describe how geologists use seismic waves to locate an earthquake’s epicenter.

A

If you know when P waves and S waves arrived at a seismograph after an earthquake, you can find the distance from the seismograph to the epicenter and draw circles on a map at three stations and where they connect is the epicenter.

20
Q

Describe specific landform and fossil evidence that supports the hypothesis that Africa and South America were once joined.

A

They could fit together, both had folded mountains, Glossopteris fossils, and Mesosaurus fossils that fit together on the edges of the continents.

21
Q

According to the theory of plate tectonics, explain what causes changes in Earth’s surface.

A

It states that the Earth’s plates are in a slow, constant motion, driven by convection currents in the mantle, which explains the formation, movement, and subduction of Earth’s plates.

22
Q

Contrast an island arc and a volcanic island.

A

An island arc is a string of islands that progresses in age resulting from volcanoes and a volcanic island isn’t related by age.

23
Q

Describe the three types of volcanoes.

A

Shield, cinder cone, composite