CHPTR 10 Earthquakes and Earth's Interior

Question 1

hypocentre/focus

Answer 1

location where the fault initially breaks or explosion happens

Question 2

epicentre

Answer 2

point on surface directly above hypocentre

Question 3

Plates move how many cm per year

Answer 3

1-10cm

Question 4

Earthquakes convert elastic energy to

Answer 4

kinetic energy and heat energy

Question 5

foreshocks

Answer 5

small tremours before major earthquakes

Question 6

elastic rebound

Answer 6

rocks spring back to original shaped

occurs during earthquake

Question 7

causes of earthquakes

Answer 7

movement of faults

• underground nuclear explosions
• oil + gas extraction

Question 8

creeping fault

Answer 8

moves a few cm per year

Question 9

seismology

Answer 9

study of earthquakes

Question 10

seismograph

Answer 10

instrument that measures ground movement as earthquake occurs

Question 11

seismogram

Answer 11

record of an earthquake made on a seismograph

Question 12

seismologist

Answer 12

person who studies seismology

Question 13

body waves

Answer 13

travel through earth
- p waves
- s waves

Question 14

surface waves

Answer 14

travel along or just below the surface
- love waves
- rayleigh waves

Question 15

which has greater amplitude surface or body waves

Answer 15

surface

Question 16

Sequence of waves from slowest to fastest

Answer 16

Surface waves, S waves, P waves

Question 17

P-wave

Answer 17

primary wave

particle motion parallel to direction of travel
(like a sound wave)

Question 18

S-wave

Answer 18

shear wave

particle motion normal to direction of travel
(like a sine graph)

Question 19

Which wave type cannot travel through liquid

Answer 19

S-wave

Question 20

Rayleigh Wave

Answer 20

• retrograde elliptical particle motion
  (circular movement)

Question 21

Love Wave

Answer 21

• horizontal motion

Question 22

How does depth influence surface waves

Answer 22

amplitude decreases with depth

Question 23

what can you tell from one station reporting data of receive p and s waves

Answer 23

distance

Question 24

what can you tell from three stations reporting data of received p and s waves

Answer 24

epicentre location

Question 25

How to read travel Time curve for distance

Answer 25

1. measure arrived time 2. difference between p-wave and s-wave arrival time 3. look for a vertical difference on the graph that matches the arrival time 4. follow that line down to the x-axis

Question 26

How to find the time that the earthquake occurred at using a travel time curve

Answer 26

1. First solve for the distance to the Earthquake 2. circle the where the p or s wave crosses the vertical line marking your distance 3. subtract their time from their respective arrival time. ie. if at 200km, it takes the P-wave 40s to arrive, subtract 40 from the time of the P-waves arrival

Question 27

Where do most earthquakes occur

Answer 27

Pacific ocean

Question 28

Wadati-Beinoff Zones

Answer 28

dipping seismic zones in a subduction zone

Question 29

Earthquake intensity

Answer 29

qualitative measurement of the damage caused by an Earthquake

Question 30

Earthquake Magnitude

Answer 30

quantitative measurement of energy released by an earthquake

Question 31

Modified Mercalli Scale

Answer 31

Measurement of earthquake intensity based on how it affects people

Question 32

Richter scale

Answer 32

Measurement of the magnitude of an earthquake

Question 33

Increase in magnitude corresponds to what increase in amplitude

Answer 33

10x

Question 34

increase in magnitude corresponds to what increase in energy

Answer 34

30x

Question 35

Worst magnitude of Earthquake, we have seen

Answer 35

9

Question 36

Seismic moment magnitude scale

Answer 36

uses area of the fault that slips and offset of area to compute magnitude

Question 37

post glacial rebound + relation to earthquakes

Answer 37

1. large ice sheets made depressions 2. ice melted quickly 3. as surface moves to return to existing shapes, there is movement along faults

Question 38

What year was the last Cascadia earthquake

Answer 38

1700

Question 39

What was minimum magnitude of the 1700 Cascadian earthquake

Answer 39

M8

Question 40

liquefaction

Answer 40

1. stable soil is held together by friction 2. shaking increases space between grains; no structure; soil flows like liquid 3. buildings and sink

Question 41

What earthquake occured in 2004, causing a tsunami

Answer 41

Indonesia

Question 42

Tsunami negative wave

Answer 42

- water pushed away from shore first - retreat rise cycle - there is warning

Question 43

Tsunami positive wave

Answer 43

- water pushed directly to shore - rise, retreat, rise cycle - little warning

Question 44

aftershock

Answer 44

big earthquake puts other areas into stress, aftershocks are the Earth trying to adjust itself - smaller earthquakes following the main earthquake

Question 45

What Earthquake occurred in 2008 and resulted in landslides

Answer 45

Sichuan Earthquake

Question 46

earthquake precursors

Answer 46

short term and long term changes within the earth prior to an earthquake that assist in prediction

Question 47

Which is faster; radio waves or p waves

Answer 47

radio waves

Question 48

How far can we image with seismic waves

Answer 48

20-30km

Question 49

What happens to the path of p waves through the earth

Answer 49

as pressure increases, p-wave velocity increases; they move away from the normal

Question 50

moho

Answer 50

boundary between the Earth's crust and mantle

Question 51

moho depth

Answer 51

30-40km; up to 80 under the himilayas

Question 52

P-wave shadow

Answer 52

If you send waves straight through the earth; the p-waves will refract (due to the outer core) in such a way that they will not be seen everywhere on the other side of the Earth

Question 53

Distance to the outer core of the Earth

Answer 53

3000km

Question 54

Which has a larger shadow zone; p-waves or s-waves

Answer 54

s-waves since they cannot go through the liquid outer core

Question 55

How deep are Earthquake foci of convergent boundaries

Answer 55

>100km (Its going deep into the Earth)

Question 56

how deep are Earthquake foci of divergent boundaries

Answer 56

30

Question 57

how deep are Earthquake foci of divergent boundaries

Answer 57

30

Question 58

Maximum depth of Earthquake focus

Answer 58

600km

Question 59

Most common plate boundary in the Pacific

Answer 59

convergent

Question 60

where are most of the worlds convergent plate boundaries

Answer 60

the Pacific ocean (big subduction zones all alone the West coast)

Question 61

Most common plate boundary in the Atlantic

Answer 61

divergent