Geol-111 Earthquakes

Front 1

Seismic waves that travel through the Earth's interior:

Back 1

Body waves

Front 2

What happens as the seismic waves spread out away from the focus?

Back 2

The vibrations start to get smaller and smaller.

Front 3

A fracture along which movement occurs:

Back 3

Fault

Front 4

The amplitude or heigth of the largest seismic wave in an earthquake:

Back 4

Magnitude

Front 5

Where is the epicenter located?

Back 5

Directly above the focus

Front 6

What are the 2 types of body waves?

Back 6

1) Primary (P) waves
2) Secondary (S) waves

Front 7

What percent of earthquakes are shallow focus earthquakes?

Back 7

85%

Front 8

Where are the most intense vibrations generated?

Back 8

At the focus

Front 9

Seismic waves that travel along Earth's surface:

Back 9

Surface waves

Front 10

A vibration of the Earth:

Back 10

Earthquake

Front 11

What do you need to locate an earthquake's epicenter?

Back 11

At least 3 seismographs

Front 12

The effect an earthquake has on people and property:

Back 12

Intensity

Front 13

What was the magnitude of the 1989 World Series earthquake?

Back 13

7.1 on the Richter Scale

Front 14

How deep are shallow focus earthquakes?

Back 14

0-100 kilometers deep

Front 15

Point where the earthquake originates; where the actual break occurs:

Back 15

Focus

Front 16

Compressional waves that expand and contract and vibrate w/ a push-pull motion:

Back 16

Primary (P) waves

Front 17

What type of seismic waves are needed to locate an earthquake's epicenter?

Back 17

Only body waves:
1) primary (P) waves
2) secondary (S) waves

Front 18

What is used to measure an earthquake's intensity?

Back 18

The Modified Mercalli Scale (Roman numerals I.- VII.)

Front 19

What percentage of earthquakes are intermediate focus earthquakes?

Back 19

12%

Front 20

The movement or vibrations that are produced as stress is released along a fault:

Back 20

Seismic waves

Front 21

A seismic sea wave caused by displacement of the ocean floor:

Back 21

Tsunami

Front 22

What are the 2 types of surface waves?

Back 22

1) Rayleigh (R) waves
2) Love (L) waves

Front 23

Instrument that records seismic waves:

Back 23

Seismograph

Front 24

Where will the maximum amount of damage and fatalities in an earthquake occur?

Back 24

At the epicenter

Front 25

The boundary between the North American and Pacific plates:

Back 25

The San Andreas Fault

Front 26

At what depths do deep focus earthquakes occur?

Back 26

350+ kilometers

Front 27

Waves that vibrate perpendicular to the direction of travel:

Back 27

Secondary (S) waves

Front 28

What is used to measure an earthquake's magnitude?

Back 28

The Richter Scale (logarithmic scale)

Front 29

"Ground zero" zone:

Back 29

Epicenter

Front 30

What type of seismic waves cause the most property damage during an earthquake?

Back 30

Surface waves

Front 31

Point on the Earth's surface that lies directly above the focus:

Back 31

Epicenter

Front 32

How deep are intermediate focus earthquakes?

Back 32

100-350 kilometers

Front 33

What type of foundation or ground is most stable during an earthquake?

Back 33

Bedrock

Front 34

Approximately how much more energy is released in a 6.5 Richter magnitude earthquake than in one with a magnitude 5.5?

Back 34

30 times

Front 35

The "snapping back" of rock to its near-original shape after an earthquake:

Back 35

Elastic rebound theory

Front 36

What percentage of earthquakes are deep focus earthquakes?

Back 36

3%

Front 37

Of the seismic waves produced by an earthquake, which type travels fastest and has the highest velocity?

Back 37

P-waves

Front 38

An earthquake’s source of energy is located at the _____________, but the location at the land surface above that point is called the ______________.

Back 38

focus, epicenter

Front 39

What is the most dangerous type of surface waves?

Back 39

Love (L) waves

Front 40

Where do most earthquakes occur?

Back 40

At plate boundaries

Front 41

Which seismic wave will reach seismographs first?

Back 41

P waves

Front 42

Effect of earthquake that occurs if there is wet, sandy ground; when the ground starts to shake, the sand grains lose contact w/ eachother and lose their stability:

Back 42

Liquifaction

Front 43

Going up one whole unit on the Richter scale represents how much of an increase?

Back 43

10-fold increase in AMPLITUDE

30-fold increase in ENERGY

Front 44

The distance to an earthquake epicenter is determined by measuring what?

Back 44

The time delay between the arrival of P and S waves.

Front 45

Seismic waves that produce circular, rolling movements; similar to water waves:

Back 45

Rayleigh (R) waves

Front 46

What earthquake magnitude is needed to cause a tsunami?

Back 46

Magnitude 8+ earthquake

Front 47

What is the current rate of drifting for the San Andreas Fault?

Back 47

2 inches per year

Front 48

What is the smallest earthquake magnitude that can be felt by humans?

Back 48

Magnitude of 2

Front 49

What were the largest historical earthquakes to ever occur along the San Andreas Fault?

Back 49

San Francisco earthquakes of 1857 and 1906

Front 50

Studies show that over the past 1,400 to 1,500 years large earthquakes along the San Andreas Fault have occurred at what intervals?

Back 50

About 150-year intervals

Front 51

What were the most widely felt earthquakes in the recorded history of North America?

Back 51

A series of earthquakes that occurred in 1811-1812 near Missouri.

Front 52

What type of plate boundary is the San Andreas Fault

Back 52

Transform plate boundary

Front 53

What earthquake magnitude would not be felt except by a very few people under favorable conditions?

Back 53

I. on the Modified Mercalli Scale

Front 54

What was the intensity and magnitude of the 1906 San Francisco earthquake?

Back 54

Magnitude of 8.3 on the Richter Scale

Intensity of XI. on the Modified Mercalli Scale

Front 55

At what magnitudes are earthquakes considered to be potentially damaging?

Back 55

Earthquakes with a Richter Scale of 5 or higher.

Front 56

What is believed to be the total accumulated displacement from earthquakes and shifting along the San Andreas Fault since it came into being 15-20 million years ago?

Back 56

At least 350 miles

Front 57

The entire San Andreas Fault system is more than ____ long and extends to depths of at least ____ within the Earth.

Back 57

800 miles, 10 miles

Front 58

Seismic waves that vibrate with a swinging, side-by-side motion:

Back 58

Love (L) waves

Front 59

When one level of a multi-story building collapses and all other floors remain intact:

Back 59

Pancaking

Front 60

Which earthquake effect causes the most property damage, injuries, and fatalities?

Back 60

Ground shaking

Front 61

Sections of a fault where there have not been any earthquakes for a long period of time:

Back 61

Seismic gaps

Front 62

Some change that happens prior to an earthquake:

Back 62

Precursor

Front 63

Who believes that animals are good precursors?

Back 63

Chinese

Front 64

Why was the damage of the 1985 Mexico City earthquake so bad?

Back 64

Because Mexico City was built over an ancient lakebed; the weak sediments caused liquifaction.

Front 65

List 5 effects of earthquakes:

Back 65

1) Ground shaking and rupture
2) Displacement of land surfaces
3) Fires
4) Slope failures (liquifaction/landslides)
5) Tsunami

Front 66

Earthquake A has a magnitude of 8. Earthquake B has a magnitude of 5. How much less energy does Earthquake A release than Earthquake B?

Back 66

27000 times

Front 67

Earthquake A has a magnitude of 3. Earthquake B has a magnitude of 7. How much greater is the size of the vibration of Earthquake B than Earthquake A?

Back 67

10000 times