Test 1 stuff Flashcards
(201 cards)
1
Q
_____ are common and seismic hazard is high throughout the carribean
A
earthquakes
2
Q
earthquakes cannot be reliably ___ or ___
A
predicted or mitigated
3
Q
earthquake is composed of 3 forces
A
stress, strain, strneght
4
Q
stress of an earthquake is
A
force per area
5
Q
strain of an earthquake is
A
% distortion
6
Q
strength of an earthquake is
A
rocks break at critical values
7
Q
rocks deform ____, then rebound during an earthquake rupture
A
elastically
8
Q
when the stress exceeds the strength of the rocks along the fault, it ___
A
slips
9
Q
when the fault slips, it ____
A
releases the stress suddenly which causes an earthquake
10
Q
____ ____ are ground vibrations caused by rocks slipping along opposite sides of a fault
A
seismic waves
11
Q
why do earthquakes occur
A
elastic rebound theory,
fault rupture
12
Q
where does the rupture of an earthquake begin
A
focus
13
Q
machines that record seismic waves generated by earthquakes
A
seismographs
14
Q
where are seismic waves generated
A
generated at earthquake focus
15
Q
___ ___ travel over earth’s surface
A
surface waves
16
Q
___ ___ and ___ ____ travel through earth’s interior
A
primary waves and secondary waves
17
Q
seismic waves arrive in which order
A
primary, secondary, and surface
18
Q
body waves travel where
A
through earth
19
Q
surface waves travel where
A
along earth’s surface
20
Q
2 types of surface waves
A
Rayleigh and love waves
21
Q
2 types of body waves
A
P/S waves
22
Q
have a push/ pull compressional motion (slinky)
travel through solids, liquids, and gases,
greatest velocity of all earthquake waves
4.8km/sec in continental crust
A
primary (P) waves
23
Q
up-down motion
travels only through solids
slower velocity than P waves
3km/sec in continental crust
A
S waves
24
Q
place within earth where earthquake waves originate
A
focus
25
point on the surface directly above the focus
epicenter
26
intersection of 3 circles from 3 recording stations is the
epicenter
27
each release in magnititude releases ___ times more energy
32
28
measure of the degree of earthquake shaking at a given locale based on the amount of damage
mercalli intensity
29
introduced by Charles Richter in 1935
| measures the amplitude of sesmic waves
magnitude
30
measure very large earthquakes
| derived from the amount of displacement that occurs along a fault zone and rupture area
moment magnitude (Mw)
31
causes pressure in pores between grains to increase and turns the substrate into a fluid
liquefaction of the ground
32
during liquefaction
saturated material turns fluid and underground objects may float to the surface
33
when is amplitude of shaking the ground greatest?
unconsolidated sediment and artificial fill
34
liquefactions sometimes causes
sand volcanoes or sand boils
35
harbor wave
tsunami
36
formed by something that rapidly moves large amounts of water
tusanmi
37
uplift of seawater during thrust faulting produces surge of water
tsunami
38
a tsunami is only a few ____ high in the deep ocean
cm
39
how fast do tsunamis travel
speed of a jetliner , so early warning systems are possible
40
tsunami sources from most frequent to less frequent
oceanic earthquakes, submarine landslides, volcanoes, meteor impact
41
estimates the probability that an earthquake of a certain magnitude will occur in a particular area during a specific time
earthquake forecasting
42
usable earthquake prediction has these factors
time interval in which quakes occur,
region where quakes occur
magnitude range of predicted quake
43
two forecasting strategies for earthquakes
find a specific precursor
| forecast a general pattern
44
earthquake clustering theory
quakes are more likely when there are other quakes
45
seismic gap theory
quakes are due if they have not happened in a while
46
precursors to earthquakes
change in # of quakes, slow ground motion, radon's emission, electrical resistivity, electromagnetic waves, water chemistry, seismic wave velocity, changes in animal behavior
47
estimate of the avg amount f time between large eq's in a given location or on a given fault
recurrence interval
48
reduces eq's generated forces acting on buildings
base isolation
49
more cohesive to less cohesive
damp sand, dry sand, water saturated snad
50
most common type of meteorite, 75-90% silicon, 10-25% Nickel-iron alloy
stony asteroid
51
likely from core of asteroid, mostly nickel-iron alloy
iron asteroid
52
shows which minerals are stable at depth
High P + T experiments
53
does earth's magnetic field wander?
yes
54
has earth's magnetic field reversed/
yes
55
dipole points ot south
normal polarity
56
dipole points to the north
reverse polarity
57
earth's chemical layers
core(iron /nickl/sulfur) --> mantle (silicate material) --> crust (granite/ basaltic rocks)
58
earth's physical layers
inner core (rigid) --> outer core (liquid) --> mesosphere (rigid) --> asthenosphere --> plastic --> lithosphere (rigid) --. ocean
59
seismic waves ____/____ at the interfaces between layers within the earth
reflect / refract
60
S waves DO NOT travel where
outer core
61
higher density in ____ vs mantle
outer core
62
describe S waves speed
increase in strong lithosphere
slight decrease in speed in weak asthenosphere
increase below asthenosphere in upper mantle
increase below the 410 KM mantle discontinutiy
increase below the upper / lower mantle transition.
63
geothermal gradient in normal continental crust is ___ to ____ per km
20 to 30 C
64
temperature near base of lithospehre
1400 C
65
outer core temperature
3000 C
66
inner core temperature
5000 C
67
in the p-wave shadow zone
no P or S waves recorded
68
in S wave shadow zone
only P waves recorded
69
p wave shadow zone is from
105 -142 due to reaction when they enter / leave the core
70
S wave shadow zone is from
105-180 because they cannot travel through outer core
71
sphere's radius or inner core radius is
1216 kim
72
what makes up the inner core
iron nickel / iron nickel alloy
73
outer core radius
2270 km
74
what makes up outer core
iron and nickl
75
lower mantle is call dhte
mesophere
76
lower mantle is made up of
peridotite
77
part of upper mantle
asthenosperhe
78
velocity of seismic waves increases where
mohorovicic discontinuity
79
what separates crust from underlying mantle
mohorovicic discontinuity
80
is part of the crust / upper mantle
lithospehree
81
has a basaltic composition made up of Fe, Mg, SiO2 and is younger than the continental crust
oceanic crust
82
lower oceanic crust
gabbro
83
upper continental crust
basalt
84
continental crust is made up of elements
Na, K, SiO2
85
continental crust contains
granite
86
theory that outer rigid layer of the earth (lithosphere) is divided into plates that move acrosss the earth's surface relative to each other
plate tectonics
87
who proposed the continental drift theory in 1912
weagner
88
evidence for continental drift theory
similar rock sequences in Appalachians / Great Britain/ other places
rock sequences contain rocks that form in tropical swamps. environments not found in current geographic locations
evidence of glacial activity where glaciers weren't
fossils include fresh water creatures that could not swim across the ocean
89
evidence for pangea
wegnr noticed the folowing features matched on continents now separated by Atlantic Ocean
90
why was Wegner condemmned
bc he could not provide mechanism for movement
91
conviction in mantle could be ____ to drive movement of continents
mechanism
92
who proposed mantle convention theory in 1919
Arthur holmes
93
evidence for mantle conviction theory
seafloor bathymetry, seafloor ages, magnetic stripes on seafloor, younger seafloor = underwater mountains
94
subduction zones = ____ margins
destructive margins
95
mid-ocean ridges = _____
constructive margins
96
at transform boundaries
crust is not created or destroyed
97
transform boundaries
```
faults connect segments of a divergent boundary
mountains = none (small)
earthquakes are shallow
no volcanoes
san Andreas fault
slide past each other
```
98
at divergent boudnaires
crust is created. youngest crust on planet at this boundary
99
divergent boundaires
```
yes for mountains
eq's shallow
yes to volcanoes
example mid Atlantic ridge, East African rift, red sea
separate
```
100
at convergent boundaries
Collin of two continental plates . crust is not created/ destoryed
101
convergent boundaires
```
mountains are the highest
eq's are shallow-moderate
no volcanoes
Himalayas
slam into each other
```
102
at convergent subduction boundary
crust is destroyed
103
what happens at convergent subduction boudnary
collision of two oceanic plates of collision of oceanic and continental
104
ocean-ocean boundaries form what
volcanoes on ocean floor/ volcanic island arcs
105
examples of ocean-ocean boundaries
Mariana / Tonga islands
106
convergen subduction
```
produces deep oceanic trenches
forms mountains
forms volcanoes
eq's shallow- deep
examples - andes mountains
```
107
originate deep within asthenosphere as molten rock which rises/ melts through the lithosphere plate forming a large volcanic mass at a hotspot
mantle plumes
108
where plates meet/ interact are ____
active margins
109
solid rock, located in crust / upper mantle, begins to melt
magma
110
to melt rocks at lower crust/ upper mantle we also need
additional heat
pressure
volatiles
partial meltin
111
equilibrium that exists between parts of the earth's crust which behaves as if it consists of blocks floating on the underlying mantle. rises if material is removed. sinks if material is deposited
isostasy
112
volcanoes are formed from what
igneous rocks
113
cools and solidifies beneath earth's surface (gabbros, diorite, granite)
intrusive igneous
114
cools and solidifies on earth's surface (basalt, andesite, rhyolite)
extrusive igneous rocks
115
molten or partially molten rock beneath earth's surface
magma
116
molten (solid) igneous rocks on earth's surface
lava
117
factors that determine the violence of an eruption
composition of magma, temperature of magma, amount of gases in magma
118
measure of a material's resistance to flow
viscosity
119
factors affecting viscosity
temperatues
composition
dissolved gases (volatiles)
120
higher temperature =
less viscous
121
higher silica content = ___ viscosity
| lower silica content = ____ fluid
higher viscoity
| more fluid
122
example of high silica
rhyolitic lava
123
example of low silica
basaltic lava
124
dissolved gases (volatiles) expand when they are near
the surface
125
least to greatest for composition / silica content / viscosity/ gas content / and ability to form prochalstic
basaltic (mafic) ---> andesitic--> rhyolite (felsic)
126
long chains of silicon tetrahedra increase
magma viscosity
127
viscous magma produces more
violent eruptions
128
basaltic lavas are more
fluid
129
pahoehoe lava is
braids in ropes
130
Aa lava is
rough , jagged blocks
131
gases from magma / volcanoes
5% of magma by weight
| mainly water vapor / carbon dioxide
132
pyroclastic materials are
fire fragmenets
133
pumice is from
frothy lavafr
134
lapilli is
walnut size
135
cinders are
pea-sized
136
conduit
pipe carrels gas-rich magma to surface
137
vent
surface opening
138
steep-walled depression at the summit
crater
139
summit-depression greater than 1 kim
caldera
140
broad, slightly domed
primarily made of basaltic (fluid) lava
generally large size
mayan loa in hawaii
shield volcanoes
141
built from ejected lava fragments
steeep slope angle
small size
occur in groups
cinder cones
142
```
most = adjacent to pacific ocean
large size
interbedded lavas and pyroclastic
most violent
Mt. Rainer , guatemala
```
stratovolcanoes (composite cone)
143
lahar
volcanic mudflow
144
nuee ardente
fiery cloud
145
resistant vents left standing after erosion removed volcanoes cone
ship rock, NM
volcanic necks
146
what controls eruption styel
magma composition
magma temp
gas content of magma
147
why is there a volcanoe in
italy
hawaiii
kenya
italy - plate tectonic convergence zone
hawaii = hot spot
kenya - continentla rift zone
148
ocean -ocean convergent plate boundary example
Aleutian Islands, Japanese archipelago
149
examples of hotspots
hawaii, yellowstone
150
general term that refers to all changes in the original form and/or size of a rock or body
deformation
151
most crustal deformation occurs where?
plate margins
152
deformation incise faulting or rigid rocks that can be ___
bent
153
brittle rocks are in
shallow crust
154
ductile rocks are in
deeper crust
155
permanet deformation , rock remains deformed
plastic
156
like a spring, release stress, and rock returns to original shape
elastic
157
strain accumulates to a point where the rock breaks (earthquakes
brittle
158
ductile rocks are what type of deformation
plastic
159
factors that influence the strength of a rocks
temperature and confining pressure
rock/mineral type
time
strain rate
160
3 types of stress
compressive
tensional
shear
161
squeeze and shorten a bodyq
compressive stress
162
stretch a body and tend to pull it apart
tenionsal stress
163
push two sides in opposite directions (twist or tears)
shearing
164
the 3 types of stress will determine what
what type of deformation will occur
165
determines whether a material behaves in a brittle of ductile fashion
strain rate
166
basic source of geologic information in the field
outcrop
167
represent the rock formation exposed at earth's surface
geologic maps
168
diagrams showing the features that would be visible if vertical slices were made through part of the crust
geologic cross sections
169
orientation of a horizontal line within a plane
strike
170
angle of a layer of rock is tiled with respect to the horizontal
dip
171
rocks bent into a series of waves--- most ___ result from compressional forces which shorten and thicken the crust (ductile, plastics)
folds
172
upfolded or arched, rock layers (A-shaped), oldest rocks in center
anticlines
173
downloaded rock layers (U-shaped), youngest rock - center
synclines
174
folds in rocks can be what
symmetricla
asymmetrical
overturned
175
limbs are mirror images. dip symmetrically from axis plane
symmetrical fold
176
limbs are not mirror images . one limb dips more steeply than the others
asymmetrical
177
one limb is tiled beyond the vertical
overturned
178
where folds die out
plunging
179
circular or slightly elongated
upward displacement of rocks
oldest rocks in core
oldest deformation exposed on surface
dome
180
circular or slightly elongated
down-warped displacement of rocks
youngest rocks in core
basin
181
movement along the inclination (dip) of fault plane
dip-slip faults
182
dominant displacement is horizontal and parallel to the trend or strike
strike-slip faults
183
rock above the fault surface
hanging wall
184
rock below the fault surface
footwall
185
hanging wall block moves down
associated with extension
prevalent at spreading center / rifts
caused by tensional foces
normal fault
186
hanging wall block moves up
caused by strong compressional forces
reverse fault is > 45 degrees
thrust fault is < 45 degrees
reverse/ thrust fault
187
older rocks on top of younger rocks
thrust fault has
188
example of normal fault
Wasatch fault in utah
189
example of thrust and reverse faults
Appalachian mountains ~ 1300 km of crustal shearing
190
large strike-slip fault that cuts through lithospehere
transform fault
191
no up-down motion of hanging walls - blocks slide past each other
transform faults
192
examples of a right-lateral transform faults
san Andreas fault
193
other deformation structures
cataclysmic textures, fault breccia , mylonite
194
brittle fractures along which no appreciable displacement has occured
joints
195
most ___ are formed when rocks in the outer - most crust has deformed
joints
196
extension of continental crust produces normal faults with high dip angles in the upper crust that flatten with depth, forming curved fault surfaces
tensional tectonics
197
compression of continental crust occurs on low-angled thrust faults
compressive tecctonics
198
shearing of continental crust occurs on a nearly vertical strike-slip fault
shearing tectontics
199
example of compressive tectnoics
Appalachians / himalays
200
example of shearing tectonics
san Andreas fault
201
examples of tensional tectonics
mid Atlantic rift
basin and range in west US
lake tanganyika
