MODULE 3: EARTHQUAKES & PLATE TECTONICS Flashcards
(90 cards)
1
Q
Rock Deformation
A
stress & strain
2
Q
Stress
a force
A
the force acting on a surface may be greater in certain directions than in others
3
Q
Strain/Deformation
A
change in volume or shape of rock in response to stress
4
Q
Pressure
A
uniform stress in all directions
5
Q
Not all plate boundaries have volcanoes.
A
All plate boundaries have earthquakes.
Earthquakes define plate bourndaries
6
Q
Transform Fault
A
Strike-Slip Fault
7
Q
Highest magnitute earthquake ever recorded
A
9.5 in Chile
8
Q
Every time a fault slips (ruptures) an earthquake occurs
A
Earthquakes are caused by a fault rupturing and asudden release of energy through the Earth’s crust in the form of seismic waves
9
Q
Province
A
area that has the same type of plate movement
10
Q
Elastic Rebound Theory
how earthquakes occur
A
- a fault is locked but continuous & builing tensional stress
- causes temporary deformation along fault until it reaches it’s breaking point
- energy releases abruptly and earthquake occurs
11
Q
potential energy is released in the form of elastic energy
A
12
Q
Seismic waves
A
first two waves released (P-waves and S-waves) are called body waves
13
Q
Focus/Hypocenter
A
where the rupture occurs & energy is initially released
14
Q
Epicenter
A
surface expression of focus
15
Q
P-waves - Primary wave (comPressional)
A
- a wave consisting of alternating pulses of compression and expansion
- rock movement is parallel to wave direction
- can pass through ANY medium
- faster (~3-5mi/s)
slinky, accordian
16
Q
S-Waves - Secondary Waves (Shear)
A
- rock is subjected to side-to-side or up-and-down forces (perpendicular)
- not transmitted through liquid
- slower (~2mi/s)
17
Q
Surface waves
A
travels parallel to earth’s surface, occurs when body waves hit the surface
18
Q
Love waves
A
slither like a snake
more destructive than Rayleigh
19
Q
Rayleigh waves
A
roll like the ocean
20
Q
Seismograph
A
instrument that detects and measures vibrations (seismic waves
21
Q
Seismogram
A
the paper record made by a seismograph
22
Q
Reelfoot Rift
A
failed rift under the MIssissippi river
23
Q
Highest elevation on earth
8848m, 29035ft, 5.5mi
A
Mount Everest, Himalayas, collision zone, convergent plate boundary
24
Q
lowest elevation on Earth
11000m , 36080ft, 7mi
A
Marianas Trench, challenger deep, convergent plate boundary
25
continental shelf edge or break
where low-density, thick, felsic continental crust meets dense, thin, mafic ocean crust
26
geologic edge of a continent
continental slope and continental rise
27
Jacques Piccard and Donald Walsh
went down to the Marianas Trench in 1960, in the Trieste
28
James Cameron
solo travel to Marianas Trench
29
Alfred Wegener
## Footnote
Meterologist, German Polar researcher
studied weather patterns on Greenland served in German army WWI
30
Alfred Wegener
* noticed puzzle-piece like fit of continents
* proposed a supercontinent once existed Pangaea
* hypothesized the idea of continental drift
31
continental drift
the slow, lateral movement of continents across the earth
32
Drifters
continents have drifted slowly
over time to their modern positions
33
Fixists
positions of continents and oceans have always looked like they do today
34
Pangaea
Laurasia (north)
Gondwanaland (south)
35
Gondwanaland
Africa, South America, Madagascar, Sri Lanka, Antarctica, Australia
36
Laurasia
North America, Eurasia
37
Continental shelf edges
fit puzzle-piece theory even better than land edges
38
matching rock types and rock ages
strongly correlated across Gondwanaland continents
39
glacial tillite
deposited in late carboniferous,
lithified glacial till
40
glaciers
form on land (not in water) from snowfall accumulation and flow outward (like pancake butter)
40
glacial till
a poorly-sorted glacial deposit
41
Glossopteris - ancient fern tree, cold loving fern
found in permian age rock layers/coal beds across all Gondwanaland continents
## Footnote
not best evidence
42
Mesosaurus
## Footnote
.5 meters, fresh water
south africa and south america,
permian age rocks,
couldn't have swam across salt water ocean
43
Lystrosaurus
triassic and permian,
antarctica, india, and africa,
small dog
44
Cynognathus
## Footnote
"dog jaw" heavily built animal
early to middle triassic
45
matching modern life
madagascar lemurs, match indian lemurs better than african lemurs
46
india and madagascar
used to be one land mass
47
tethys sea
48
Harry Hess - oceanographer
## Footnote
promoted to Rear Admiral
* naval captain during WWII on U.S.S. Cape Johnson
* ship had SONAR technology
* pacific ocean
49
Coral reef ringed volcanic islands
above sea level, necklaces of coral
50
Coral atolls
ring/encklace of coral reefs set atop an eroded volcano encircling a brackish (rain and ocean water) water lagoon,
51
Sonar
echo soundings
52
Iwo Jima
coral reef ringed volcanic island
53
Midway Atoll
an atoll with an naval landing strip built on it
54
Guyot (tablemount)
submerged volcanoes observed using sonar technology,
an isolated, undersea volcano with a flat top
55
seamount --> volcanic island
coral atoll --> guyot/tablemount
56
proposed seafloor was moving
proposed hot spot, stationary mantle plume
57
Deep-Sea Trenchs
where guyots go to die
58
Loihi
potential new Hawaiian island
59
Mid-Ocean Ridge (tear that's opening)
## Footnote
normal fault
a continuous submerged mountain ridge that forms in the middle of the Atlantic Ocean
## Footnote
has strong depression on top
60
Marie Tharp
Bruce Heezen
## Footnote
Columbia University oceanographers
used sonar to map the entire Atlantic Ocean
61
Marie Tharp
## Footnote
queen
masters in geology
couldn't go on ocean expeditions b/c woman=bad luck
notices ocean valleys and earthquakes are related
proved Wegener's continental drift theory
62
Mid-Atlantic Ridge
decompression volcano range
63
rifting
ripping, tensional, normal fault
64
if new crust is being created at mid ocean ridges, and the Earth isn't getting any bigger, then by Conservation of Mass...
Ocean floor is being destroyed in trenches
## Footnote
plate tectonic model
65
mid ocean ridge
## Footnote
decompression, creating
oceanic trench
## Footnote
subduction, destroying
66
tsunamis occur at subduction zones
more dense plate drags down a lip of less dense plate until it reaches breaking point and pops back into place
67
Paleomagnestism (1950's -60's)
the study of Earth's past magnetic signal preserved in ancient iron breaking rocks preserved in ancient iron-barining rocks (basalt)
68
magnetic pole vs georaphicals poles
we have a magnetic field b/c of metals in the heat and metals in the mantle
69
vector
magnitude and direction
70
When an iron-rich igneous rock cools.
1. it becomes magnetic
2. it takes on a magnetic vector for that location and latitude at that point in time
71
Curie temperature
580 degrees celcius
72
Apparent polar wander
paleomagnetic signal in ancient rocks appears as though the magnetic poles have wandered
73
magnetic north pole is fixed
continents are drifting
74
magnetic reversals
a period of time inwhich Earth's magnetic field reverses itself
75
magnetic reversals
are completely unpredictable
76
tectonic plates do one of three things
spliting apart (rift)
colliding
sliding past one another
77
divergent plate margin
## Footnote
tensional stress, extension, pulling, spreading
plates move apart
78
afar triangle
triple junction
african, arabian, indian plates
## Footnote
east african rift valley - not plate margin yet
79
failed rift
new madrid seismic zone
ancient rift no longer active
80
divergent plate boundry process
1. river valley, linear lakes (thinning)
2. continued rifting, new ocean floor/ridge (ripping, salt water)
3. mature ocean basin, well-developed mid-ocean ridge
81
red sea and gulf of aden, gulf of california
linear saltwater seas
82
convergent margin
## Footnote
himalayas
where plate smush together
* conitnent-continent (no volcanoes)
* ocean-continent
* ocean-ocean
## Footnote
reverse faults, thrust faults
83
himalayas
## Footnote
continental-contintental
tibetan plataeu, ganges plain
india and eurasia
high, non-volcanic mountain range
84
cascades, andes
## Footnote
ocean-continent
subduction zones
85
convergent plate boundaries
have the strongest earthquakes, big land slides
86
ring of fire, western Aleutian islands, Kamchatka, Japan, Marianas islands, Carribean islands
## Footnote
ocean-ocean
volcanic island arcs
subduction
87
accreted, exotic terrane
wedge of deformed oceanic crust
88
shore closest to trench
highest risk of tsunami
89
islands curve towards more dense plate
