Geology Test 3

Front 1

Deformation

Back 1

Changes in the form and/or size of rock bodies.
-Most crystal ___ occurs along plate margins because that's where all the action occurs; movement of the plates.

Front 2

Stress

Back 2

Force applied to a given area.
-A type of deformation
-3 Different types: Compressional, Tensional, Shear

Front 3

Compressional Stress

Back 3

Shortens rock
Causes Folds

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Front 4

Tensional Stress

Back 4

Pulls apart rock
Causes a normal fault

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Front 5

Shear Stress

Back 5

Slides one rock past another
Ex: occurs when hand pushes the top of a deck of playing cards

Front 6

Rock

Back 6

Deform by folding, flowing, or fracturing

Front 7

Brittle Deformation

Back 7

Rock doesn't reach its elastic limit (or limit of strength), deforms by fracturing

Front 8

Factors that influence rock strength

Back 8

Temperature
Pressure
Rock Type
Time

Front 9

Folds

Back 9

A series of wave-like undulations
-Characteristics: from compressional stresses which shorten and thicken crust
-Parts: limbs and axial plane
-Types: anticline, syncline, monoclines, dome, basin

Front 10

Anticline

Back 10

Arched rock layers, oldest rock in center and youngest rock at the limbs

Front 11

Syncline

Back 11

Downfolds of rock layers, youngest rock in center

Front 12

Monoclines

Back 12

Large, step-like

Front 13

Dome

Back 13

Upward displacement, circular structure

Front 14

Basin

Back 14

Downward displacement, circular structure; Oldest rock located in the center.

Front 15

Faults

Back 15

Fractures with displacement
-Movements across these cause most EQs
-2 Major types: Dip-slip and Strike-slip

Front 16

Dip-slip Faults

Back 16

-Movement parallel to dip of fault.
-Hanging wall (rock surface above fault) and footwall (rock surface below fault.
-3 types: Normal fault, Reverse fault, and and Thrust fault

Front 17

Normal Fault

Back 17

Hanging wall moves down relative to foot wall.
-Accommodates lengthening, extensional forces.

Front 18

Reverse Fault

Back 18

Hanging wall moves up relative to footwall (>45 degrees)

Front 19

Thrust Fault

Back 19

Hanging wall moves up relative to footwall (<45 degrees)

Front 20

Strike-slip Faults

Back 20

Displacement parallel to strike of fault.
-Two types: Right-lateral and Left-lateral
-San Andreas
-Results from shear stress

Front 21

Transform Fault

Back 21

Large, cuts through the lithosphere; accommodates motion between two crustal plates.
-A type of strike-slip

Front 22

Joints

Back 22

Fractures with no movement. They occur in groups, with a lot of chemical weathering.
-Mineral deposits

Front 23

Earthquake

Back 23

Vibration of the earth produced by a rapid release of energy (elastic strain).
-Energy waves radiate in all directions from focus
-Epicenter directly above focus (hypocenter) on surface
-Instruments around the world record the energy
-Occur when a fault moves

Front 24

Elastic Rebound Theory

Back 24

-Rocks bend and store elastic energy
-Resistance holding rocks together at fault overcome at weakest points (focus)
-EQs occur as rock "springs back" to original shape

Front 25

Foreshocks

Back 25

Small EQs before major EQs
-Can occur days or years beforehand

Front 26

Aftershocks

Back 26

Adjustments after major EQ generate smaller EQs

Front 27

Displacement

Back 27

Occurs along segments 100-200km long, via 3 ways:
1) Slow, gradual (fault creep)
2) Slip by producing small EQs
3) Stone elastic energy for 100s of years before rupturing in major EQs

Front 28

Seismology

Back 28

Study of EQ waves

Front 29

Seismographs

Back 29

Records seismic waves
-Records movement of Earth in relation to a stationary mass on a rotating drum

Front 30

Seismograms

Back 30

Records obtained of EQ waves

Front 31

Surface Waves

Back 31

Travel along outer part of Earth, and cause the greatest destruction.
-Exhibit greatest amplitude and slowest velocity
-Two motions: back and forth (Love wave or L- wave); rolling (Rayleigh wave or R- wave)
-Last to arrive

Front 32

Body Waves

Back 32

Travel through the Earth's interior
-Two types: Primary and Secondary

Front 33

Primary (P) Waves

Back 33

Push-pull motion; travel through solids, liquids, and gases
-First to arrive

Front 34

Secondary (S) Waves

Back 34

"Shake" motion at right angles; travel through solids, at a slower velocity but greater amplitude than P Waves
-Second to arrive

Front 35

Where are EQs?

Back 35

-80% Circum-Pacific
-15% Mediterranean- Asiatic
-5% interior plates and MORs

Front 36

Intensity

Back 36

Degree of shaking at locality

Front 37

Magnitude

Back 37

Estimates the amount of energy released

Front 38

EQs are described by....

Back 38

Their intensity and magnitude