PEO 2 - Lecture Cards Earthquakes-Seismology

Question 1

When was the Charleston Earthquake?

Answer 1

1886

Question 2

Where are deep focuses only found?

Answer 2

At subduction zones

Question 3

Tension forces are _____.

Answer 3

Spreading apart

Question 4

Subduction zones where earthquakes get deeper the further away they are and shallower closer to the resulting trench are known as…

Answer 4

(Wadati-)Benioff Zones

Question 5

Where are epicenters located? (At or below the surface?)

Answer 5

At the surface

Question 6

Where are foci located? (At or below the surface?)

Answer 6

Below the surface

Question 7

What is the correct order of waves received during Earthquakes

Answer 7

P-waves then S-waves then surface waves

Question 8

Ground roll is from what kinds of waves?

Answer 8

Rayleigh waves

Question 9

Ground skae is from what kinds of waves?

Answer 9

Love waves

Question 10

Each increase of on magnitude = ?

Answer 10

10x greater ground displacement, and 31.6x greater energy released

Question 11

First motion up

Answer 11

Push away from the epicenter

Question 12

First motion down

Answer 12

Pull toward the epicenter

Question 13

Epicenter are located with at least _____ seismographs.

Answer 13

3

Question 14

What waves are high-frequency [0.5-20 cycles/sec]?

Answer 14

Body waves

Question 15

What waves are low-frequency [<0.5 cycles/sec]?

Answer 15

Surface waves

Question 16

What buildings are most affected by high-frequency vibrations?

Answer 16

Low buildings

Question 17

Low buildings are affected most by which waves?

Answer 17

Body

Question 18

What buildings are most affected by low-frequency vibrations?

Answer 18

Tall buildings

Question 19

Tall buildings are most affected by which waves?

Answer 19

Surface

Question 20

_____-frequency waves dissipate slower than _____-frequency waves

Answer 20

Low; high

Question 21

_____ buildings sway far away from the epicenter.

Answer 21

Tall

Question 22

Amplification of shaking (surface waves) low –> high.

Answer 22

Hard igneous rock, sedimentary rock, alluvium, silt/mud

Question 23

What are sand blows?

Answer 23

Ground shaking may cause wet sand to squirt up through cracks in overlying compacted mud

Question 24

Generally, _____ are small but some that formed after the 1811-1812 New Madrid (Missouri) quakes were tens of meter across.

Answer 24

Sand blows

Question 25

How does water move in a tsunami?

Answer 25

In deep water, a seismic wave is only a few centimeters high, but its speed can be >800 kilometers (~500 miles) per hour. In shallow water the speed decreases and the height increases.

Question 26

Where do rays refract at in the Earth?

Answer 26

Rays refract at boundaries between layers of different density, and eventually turn back toward the surface. Rays curve in the mantle because density increases gradually with depth, and the spherical waves become oblate.

Question 27

Why do rays curve in the mantle?

Answer 27

Rays curve in the mantle because density increases gradually with depth, and the spherical waves become oblate.

Question 28

Where is the P-wave shadow zone?

Answer 28

103-143 degrees from the point of the focus.

Question 29

Can P-waves travel through the Earth’s liquid core?

Answer 29

Yes

Question 30

What did reflected nuclear seismic waves confirm?

Answer 30

Reflected nuclear seismic waves confirmed the Earth’s solid inner core.

Question 31

Where is the S-wave shadow zone?

Answer 31

103-103 degrees from the point of the focus.

Question 32

Can S-waves travel through the Earth’s liquid core?

Answer 32

No