Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
77 Cards in this Set
- Front
- Back
stress
|
a force producing or tending to produce deformation in a body
|
|
strain
|
deformation resulting from stress (change in shape)
|
|
hydrostatic stress
|
force is applied on a body in all directions
|
|
elastic modules
|
the ratio of stress to strain is constant (rubber hand)
|
|
brittle material
|
breaks (temps down, strain up)
|
|
ductile material
|
absorbs stress by flowing (temps up, strain down)
|
|
bulk module
|
measure of "incompressibility" of a material
up incompressibility= up bulk |
|
shear module
|
measure of the "rigidity" of a material
up rigid= up shear |
|
faults
|
fractures in the earth along which there has been displacement of one side relative to the other side
|
|
reverse/thrust fault
|
towards each other (compressional stress)
|
|
normal fault
|
away from each other (tensionary stress)
|
|
strike slip fault
|
shear couple (coming together diagonally)
|
|
earthquake
|
if stress is suddenly released, elastic strain energy is too- some as seismic waves (elastic proportional to stress)
|
|
seismic waves
|
body waves that travel through earth's interior
|
|
p waves
|
longitudinal/compressional (slinky)- vibrate in the same travel direction
|
|
s waves/transverse waves/shear waves
|
rope- vibrate perpendicular to direction of travel
|
|
major earthquake hazards
|
ground shaking, liquefaction, ground displacement, flooding, fire
|
|
liquefaction
|
mixing of sand and water during earthquakes
|
|
tsunami
|
surface wave that travels on the ocean
|
|
predicting earthquakes
|
swelling in rocks producing doming of area, ground tilting, increased radon emissions, changes in water levels
|
|
controversial tactics to predict earthquakes
|
radio frequency signals, animal behavior
|
|
San Andres fault
|
strike: slip fault that moves sideways, earthquakes take place along plate edges (oceanic or continental) or faults
|
|
shallow earthquake
|
60 km/40 miles
|
|
intermediate earthquake
|
60-300 km
|
|
deep earthquake
|
300-700 km
|
|
what does seismic activity measure?
|
strength of earthquake (size, type, frequency, magnitude, proximity)
|
|
level 1 earthquake
|
not felt, 1-3
|
|
level 2-3 earthquake
|
felt if sitting, 3-3.9
|
|
level 4-5 earthquake
|
noticed inside at all times, 4-4.9
|
|
level 6-7 earthquake
|
everyone notices, 5-5.9
|
|
level 8-9 earthquake
|
causes fear/panic, destroys buildings, 6-6.9
|
|
level 10+ earthquake
|
major disaster, 7-7.9
|
|
japan earthquake
|
6.9
|
|
seismometer
|
measures movement of earth (ground motion detection sensor and recording device) operates on inertia
|
|
crust
|
mohorovicic discontinuity: separates crust from mantles
|
|
oceanic crust
|
3 layers: oceanic sediments, bassalts, gabbro
|
|
continental crust
|
less dense and more felsic than oceanic
|
|
mantle
|
consists of: upper mantle, transition zone, asthenosphere, lithosphere
|
|
asthenosphere
|
decreases s waves, ductile
|
|
lithosphere
|
brittle, increases s waves
|
|
core
|
1/3 mass of planet
|
|
outer core
|
s waves not transmitting
|
|
inner core
|
p waves increase, temperature too high to melt (solid)
|
|
gravity
|
attractive force that exists between masses
|
|
gravimeter value
|
measures gravity, cluster around average but anolamies exist
positive anomaly: implies mass excess negative anomaly: implies mass deficiency |
|
isostatic equilibrium
|
the balance between blocks of crust and mantle
|
|
magnetic inclination
|
the angle the magnetic field lines make with the earths surface
90 degrees at poles 0 degrees at equator |
|
magnetic declination
|
the angle between magnetic north and true north
|
|
measuring inclination/declination
|
by measuring of rocks of KNOWN age, we can determine the locations of their continents at that time
|
|
curie temperature
|
temperature above which a material loses its permanent magnetism
|
|
origins of earths magnetic field
|
produced by the motion of electrical charges, it is associated with electrical currents produced by rotation in spinning of the core
|
|
continental drift
|
theory that continents move slowly about the earths surface, changing positions relative to each other
|
|
pangaea
|
super continent named by wegener
|
|
gondwana
|
sourthermost of two supercontinents that formed part of pangaea
|
|
laurasia
|
other part of super continent
|
|
divergent plate boundaries
|
move/pull apart
mid atlantic ridge |
|
convergent plate boundaries
|
moving towards each other
|
|
subduction
|
one plate dives under another, forms island arcs, allows continent collision
|
|
forming island arcs
|
slab melts when it reaches hot depth and leaks into crust (forming volcano)
|
|
andesites
|
common volcanic rock
|
|
oceanic- oceanic convergence
|
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)
|
|
oceanic- continental convergence
|
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
|
|
continental- continental convergence
|
when two continents meet head on, neither is subducted and instead the crust tends to buckle and be pushed upwards or sideways, himalayas
|
|
trasform fault boundaries
|
slide horizontally past each other, san andres fault
|
|
sea floor spreading
|
process in which the ocean floor is extended when two plates move apart
|
|
graben
|
depressed block of land boarded by parallel faults
|
|
ophiolite
|
suite of rocks that form at spreading centers or divergent plate boundaries
|
|
melange
|
a metamorphic rock formation created from materials scraped off the top of a downward moving tectonic plate in a subduction zone
|
|
hot spot
|
volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere
|
|
continental suture (drift)
|
geological theory that the relative positions of the continents on the earths surface have changed considerably through geologic time
|
|
obduction
|
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)
|
|
abyssal plains
|
vast, flat sediment covered areas of the deep ocean floor
|
|
continental rise
|
a wide gentle incline from an ocean bottom to a continental slope
|
|
continental shelf
|
a submerged border of a continent that slopes gradually and extends to a point of steeper descent to the ocean bottom
|
|
hydrothermal vents
|
geyser on sea floor (black smokers)
|
|
accreted terranes
|
a landmass that originated as an island arc or a microcontinent that was later added onto a continent
|
|
ocean basins
|
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
|