Geology Test 3

Front 1

CHAPTER 8

Back 1

Flash Cards

Front 2

Why do earthquakes occur on Earth?

Back 2

Because of the earths structure and plate tectonics

Front 3

What is the elastic Rebound theory

Back 3

Concept that earthquakes occur when rock elastically bends until it fractures, the fracturing generates earthquake energy and decreases the elastic energy stored in the rock

Front 4

Understand stick slip behavior of faults

Back 4

stop start movement along a fault plane caused by friction, which prevents movement until stress builds up sufficiently

Front 5

Understand earthquake cycle

Back 5

Rocks deform elastically then rebound during an earthquake rupture

Front 6

What happens during an earthquake?

Back 6

Rupture propogation and Wave propogation

Front 7

What is rupture propagation?

What is wave propagation?

Back 7

Rupture propogation- happens on faults, faults slipping spreads out along the surface

Wave propogation- causes ground shaking as earthquake energy travels as seismic waves.

Front 8

Understand how DIRECTIVITY EFFECT and SEDIMENTARY BASIN EFFECT may affect ground shaking amplitude.

Back 8

D.E= stronger shaking in the direction of rupture propogation

S.B.E= Seismic waves decrease with propogation distance

Front 9

What are body waves?

2 types?

Back 9

propogate through the interior of the earth (3D volume)
P WAVES= primary, fastest, compress/expand
S WAVES= slower, second, shear shaking, solid only

Front 10

What are surface waves?

2 types?

Back 10

Propogate near the surface, slower than body waves

L WAVES= love, move back/forth (snake)
R WAVES= Rayleigh, moves like ripples on a pond

Front 11

How does the ground shake due to different types of
seismic waves?

Back 11

On R Waves, particles underground follow a circular path as the wave passes.

Front 12

What is a seismograph?

Back 12

instruments recording seismic waves.

Front 13

Understand how to locate the epicenter of an earthquake from travel time observations of
three seismic stations.

Back 13

3 stations allow you to locate the epicenter, called triangulation.

Front 14

What is the difference between an intensity scale and magnitude of an earthquake

Back 14

Intensity scale is based on destructiveness while earthquake magnitude is determined from instrument measurements

Front 15

What measurable quantities are used to determine Richter magnitude and moment magnitude determined, respectively?

Back 15

Richter magnitude is based on max amplitude of ground movement.

Moment magnitude is based on seismic moment

Front 16

How many times more energy release, respectively, for one unit difference in earthquake magnitude?

Back 16

1 unit increase in magnitude represents 32 times increase in energy release.

Front 17

how many magnitude 8 and magnitude 7 earthquakes occur a year?

Back 17

500 times

Front 18

• Where do most earthquakes occur? Where do intermediate and deep earthquakes occur?

Back 18

Most occur @ plate boundaries.

Intermediate and Deep earthquakes occur @ convergent boundaries

Front 19

What is the fault that is the most active in US? Which two plates meet at this fault?

Back 19

San Andreas Fault.

Pacific plate meets North American plate

Front 20

What is the maximum depth an earthquake can occur on Earth?

Back 20

up to 660 kilometers deep

Front 21

At what types of plate boundaries did 2010 Haiti, Chile, and Baja earthquakes occur?
What types of faulting occurred in these earthquakes? Compare their sizes in terms of
magnitude and difference in energy release.

Back 21

Convergent

Front 22

What is liquefaction?

Back 22

water saturated sediments lose strength under shaking and behave like a liquid.

Front 23

• Understand how Tsunami waves behave differently in open ocean and near shoreline

Back 23

are imperceptible in deep water, waves grow in height as the water shallows

Front 24

How can long-term earthquake prediction be made? Is short-term earthquake prediction
feasible currently?

Back 24

avg the time between successive earthquakes (recurrence interval)

Short term earthquake prediction is not feasible.

Front 25

• Why can seismic waves be used to explore Earth's interior?

Back 25

because they travel @ different speeds in different rocks (s waves only through solid!)

Front 26

How does seismic velocity
change with depth in Earth?

Back 26

8

Front 27

What evidence did seismologists use to discover Moho,
core-mantle boundary, and two-layer-structure of the Earth's core?

Back 27

Moho- P wave arrivals have different velocities @ different stations

Core mantle- P Waves do not arrive in the P wave shadow zone.

2 layer structure- S waves dont arrive in the s wave shadow zone and the p wave relection within the core

Front 28

CHAPTER 9

Back 28

Flash Cards

Front 29

What are strain and stress in geology? Different kinds.

Back 29

Strain= with distortion only
ex(stretching, shortening,shear)

Stress= cause of strain
ex(compression, tension, shear stress)

Front 30

What does orogeny mean?

Back 30

a Mountain building event

Front 31

What are the two main types of deformation and determinant factors?

Back 31

9

Front 32

How do joints and faults form?

Back 32

Geologic processes
- cools and contracts
- decrease in pressure
-bend

Front 33

How do you describe fault geometry?

Back 33

describes strike and dip and how the strike line is perpendicular to the dip line.

Front 34

What is a strike?

Back 34

angle between fault surface trace & true north

Front 35

What is a slip?

Back 35

angle between horizontal plane & dip line

Front 36

Difference between a foot wall and hanging wall?

Back 36

you can stand on the footwall

Front 37

Know the basic types of faults

Back 37

Reverse Fault
Thrust Fault
Normal Fault

Front 38

How do you identify faults in a field?

Back 38

-discontinuous rock layers
-displaced landscape/man made features
-fault scarp: step due to dip slip

Front 39

How do you describe fold geometry?

Back 39

there is an axis and axis can be plunging or non plunging

Front 40

Know fold types, their shapes, and outcrop rock patterns

Back 40

Anticline= limbs dip away from hinge
Syncline= limbs dip toward hinge

Front 41

Where can mountain building occur?

Back 41

convergent margin orogens

Front 42

In what environment did the Andes form?

Back 42

along a convergent margin

Front 43

what does isostasy mean?

whats its consequences?

Back 43

conditions at which buoyancy force= gravitational force, isstatic equilibrium

Front 44

why do mountains have roots?

Back 44

creates extra buoyancy force

Front 45

what is orogenic collapse?

Back 45

warmer, softer, flow laterally

Front 46

What is a craton?

Back 46

consist of crust that has not been affected by orogeny for at least 1 billion years

Front 47

CHAPTER 10

Back 47

Flash Cards