Dynamic Earth

Front 1

stress

Back 1

a force producing or tending to produce deformation in a body

Front 2

strain

Back 2

deformation resulting from stress (change in shape)

Front 3

hydrostatic stress

Back 3

force is applied on a body in all directions

Front 4

elastic modules

Back 4

the ratio of stress to strain is constant (rubber hand)

Front 5

brittle material

Back 5

breaks (temps down, strain up)

Front 6

ductile material

Back 6

absorbs stress by flowing (temps up, strain down)

Front 7

bulk module

Back 7

measure of "incompressibility" of a material
up incompressibility= up bulk

Front 8

shear module

Back 8

measure of the "rigidity" of a material

up rigid= up shear

Front 9

faults

Back 9

fractures in the earth along which there has been displacement of one side relative to the other side

Front 10

reverse/thrust fault

Back 10

towards each other (compressional stress)

Front 11

normal fault

Back 11

away from each other (tensionary stress)

Front 12

strike slip fault

Back 12

shear couple (coming together diagonally)

Front 13

earthquake

Back 13

if stress is suddenly released, elastic strain energy is too- some as seismic waves (elastic proportional to stress)

Front 14

seismic waves

Back 14

body waves that travel through earth's interior

Front 15

p waves

Back 15

longitudinal/compressional (slinky)- vibrate in the same travel direction

Front 16

s waves/transverse waves/shear waves

Back 16

rope- vibrate perpendicular to direction of travel

Front 17

major earthquake hazards

Back 17

ground shaking, liquefaction, ground displacement, flooding, fire

Front 18

liquefaction

Back 18

mixing of sand and water during earthquakes

Front 19

tsunami

Back 19

surface wave that travels on the ocean

Front 20

predicting earthquakes

Back 20

swelling in rocks producing doming of area, ground tilting, increased radon emissions, changes in water levels

Front 21

controversial tactics to predict earthquakes

Back 21

radio frequency signals, animal behavior

Front 22

San Andres fault

Back 22

strike: slip fault that moves sideways, earthquakes take place along plate edges (oceanic or continental) or faults

Front 23

shallow earthquake

Back 23

60 km/40 miles

Front 24

intermediate earthquake

Back 24

60-300 km

Front 25

deep earthquake

Back 25

300-700 km

Front 26

what does seismic activity measure?

Back 26

strength of earthquake (size, type, frequency, magnitude, proximity)

Front 27

level 1 earthquake

Back 27

not felt, 1-3

Front 28

level 2-3 earthquake

Back 28

felt if sitting, 3-3.9

Front 29

level 4-5 earthquake

Back 29

noticed inside at all times, 4-4.9

Front 30

level 6-7 earthquake

Back 30

everyone notices, 5-5.9

Front 31

level 8-9 earthquake

Back 31

causes fear/panic, destroys buildings, 6-6.9

Front 32

level 10+ earthquake

Back 32

major disaster, 7-7.9

Front 33

japan earthquake

Back 33

6.9

Front 34

seismometer

Back 34

measures movement of earth (ground motion detection sensor and recording device) operates on inertia

Front 35

crust

Back 35

mohorovicic discontinuity: separates crust from mantles

Front 36

oceanic crust

Back 36

3 layers: oceanic sediments, bassalts, gabbro

Front 37

continental crust

Back 37

less dense and more felsic than oceanic

Front 38

mantle

Back 38

consists of: upper mantle, transition zone, asthenosphere, lithosphere

Front 39

asthenosphere

Back 39

decreases s waves, ductile

Front 40

lithosphere

Back 40

brittle, increases s waves

Front 41

core

Back 41

1/3 mass of planet

Front 42

outer core

Back 42

s waves not transmitting

Front 43

inner core

Back 43

p waves increase, temperature too high to melt (solid)

Front 44

gravity

Back 44

attractive force that exists between masses

Front 45

gravimeter value

Back 45

measures gravity, cluster around average but anolamies exist
positive anomaly: implies mass excess
negative anomaly: implies mass deficiency

Front 46

isostatic equilibrium

Back 46

the balance between blocks of crust and mantle

Front 47

magnetic inclination

Back 47

the angle the magnetic field lines make with the earths surface

90 degrees at poles
0 degrees at equator

Front 48

magnetic declination

Back 48

the angle between magnetic north and true north

Front 49

measuring inclination/declination

Back 49

by measuring of rocks of KNOWN age, we can determine the locations of their continents at that time

Front 50

curie temperature

Back 50

temperature above which a material loses its permanent magnetism

Front 51

origins of earths magnetic field

Back 51

produced by the motion of electrical charges, it is associated with electrical currents produced by rotation in spinning of the core

Front 52

continental drift

Back 52

theory that continents move slowly about the earths surface, changing positions relative to each other

Front 53

pangaea

Back 53

super continent named by wegener

Front 54

gondwana

Back 54

sourthermost of two supercontinents that formed part of pangaea

Front 55

laurasia

Back 55

other part of super continent

Front 56

divergent plate boundaries

Back 56

move/pull apart

mid atlantic ridge

Front 57

convergent plate boundaries

Back 57

moving towards each other

Front 58

subduction

Back 58

one plate dives under another, forms island arcs, allows continent collision

Front 59

forming island arcs

Back 59

slab melts when it reaches hot depth and leaks into crust (forming volcano)

Front 60

andesites

Back 60

common volcanic rock

Front 61

oceanic- oceanic convergence

Back 61

when two oceanic plates converge one is usually subduced under the other and in the process a deep oceanic trench is formed, island arcs (chains of volcanos)

Front 62

oceanic- continental convergence

Back 62

when an oceanic plate pushes into and subducts under a continental plate, the overriding continental plate is liefted up and a mountain range is created, earthquakes

Front 63

continental- continental convergence

Back 63

when two continents meet head on, neither is subducted and instead the crust tends to buckle and be pushed upwards or sideways, himalayas

Front 64

trasform fault boundaries

Back 64

slide horizontally past each other, san andres fault

Front 65

sea floor spreading

Back 65

process in which the ocean floor is extended when two plates move apart

Front 66

graben

Back 66

depressed block of land boarded by parallel faults

Front 67

ophiolite

Back 67

suite of rocks that form at spreading centers or divergent plate boundaries

Front 68

melange

Back 68

a metamorphic rock formation created from materials scraped off the top of a downward moving tectonic plate in a subduction zone

Front 69

hot spot

Back 69

volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere

Front 70

continental suture (drift)

Back 70

geological theory that the relative positions of the continents on the earths surface have changed considerably through geologic time

Front 71

obduction

Back 71

the edge of a tectonic plate consisting of oceanic crust is thrust over the edge of an adjacent plate consisting of continental crust (building mountains)

Front 72

abyssal plains

Back 72

vast, flat sediment covered areas of the deep ocean floor

Front 73

continental rise

Back 73

a wide gentle incline from an ocean bottom to a continental slope

Front 74

continental shelf

Back 74

a submerged border of a continent that slopes gradually and extends to a point of steeper descent to the ocean bottom

Front 75

hydrothermal vents

Back 75

geyser on sea floor (black smokers)

Front 76

accreted terranes

Back 76

a landmass that originated as an island arc or a microcontinent that was later added onto a continent

Front 77

ocean basins

Back 77

saucer like depressions of the sea bed. they vary in size from relatively minor features of the continental margin to vast structural divisions of the deep ocean