Earthquakes Flashcards

1
Q

Earthquakes are…

A

the release of energy stored as elastic deformation of rocks
propagated by seismic waves

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2
Q

a measurement of size based on the maximum amplitude of seismograph waves.

A

Magnitude

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3
Q

Magnitude is described using different scales. Which is the most accurate?

A
Richter Scale (Best near epicenter)
Moment magnitude scale—most accurate.
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4
Q

Earthquakes are caused by…

A

magma movement, volcanic eruptions, landslides,

meteorite impacts, and nuclear detonations

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5
Q

The Hypocenter (Focus)

A

the location where fault slip occurs.

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6
Q

the land surface directly above the hypocenter. Maps

often portray the location of these things.

A

Epicenter

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7
Q

On a normal fault…

A

the hanging wall moves down relative to the footwall. It most often results from extension (pull-apart or stretching).

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8
Q

In a reverse fault…

A

the hanging wall moves up relative to the footwall. It usually results from compression (squeezing or shortening).

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9
Q

A thrust fault is…

A

A special kind of reverse fault (lower slope angle)

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10
Q

strike-slip fault

A

one block slides laterally past the other block. There is no vertical motion across the fault.

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11
Q

Shallow—divergent and transform boundaries; Intermediate and deep—convergent boundaries

A

Mid-ocean ridges (divergent)

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12
Q

Earthquakes are rare below 660 km as the mantle becomes too ductile.

A

the Wadati-Benioff zone (earthquakes that trace the path of the subducting crust)

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13
Q

P-waves

A

travel by compressing and expanding the material parallel to the wave-travel direction. The fastest seismic waves and they travel through solids, liquids, and gases.

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14
Q

travel by moving material back and forth, perpendicular to the wave-travel direction. These are slower and travel only through solids.

A

S-Waves

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15
Q

What are the two body waves?

A

S-waves and P-waves

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16
Q

What are the two surface waves?

A

L-waves, R-waves

17
Q

the slowest and most destructive waves

A

L-waves (Which are a type of S-wave)

18
Q

These waves cause the ground to ripple up and down like water. Type of P-wave

A

R-Waves

19
Q

An instrument that measures ground movement

A

Seismometer

20
Q

Cause the ground to go up and down. First to arrive

A

P-waves

21
Q

Cause the ground to shake back and forth. Second to arrive.

A

S-Waves

22
Q

Cause extensive damage. Much stronger than the first waves that arrive

A

S-waves

23
Q

These waves follow quickly behind the S-waves

A

L-waves

24
Q

These are the last waves to arrive. These

waves usually last longer than the other kinds and usually cause extensive damage.

A

R-waves

25
Q

Liquefaction…

A

causes soil to lose strength. Land, and the structures on it, will slump and flow.

26
Q

Can we predict earthquakes?

A

Yes AND No. They CAN be predicted long term, NOT short term.

27
Q

Tsunami (harbor wave) results from…

A

displacement of the sea floor by an earthquake, submarine landslide, or volcanic explosion that displaces the entire volume of overlying water