question

single most important concept in earth sciences idea that the outermost part of the earth (lithosphere) is made up of twelve large plates that move past each other

answer

theory of plate tectonics

question

strong, rigid outer shell of earth that contains the crust and the uppermost part of the mantle

answer

lithosphere

question

weak, partially molten part of the earth in the upper mantle

answer

asthenosphere

question

region of the earth between the crust and the core and includes the lower lithosphere and asthenosphere

answer

mantle

question

continental crust and oceanic crust

answer

outermost part of the earth's composition

question

average thickness of continental crust

answer

40 km

question

average thickness of oceanic crust

answer

7 km

question

a crack with displacement in it; a fracture or discrete surface separating two bodies of rock which have moved relative to one another

answer

fault

question

occur where plates move away from each other; this type of plate boundary is the result of tensional stress and is characterized by normal faults

answer

divergent plate boundaries

question

volcanism and normal faulting are associated with topographic highs in the ocean basins in areas known as ________. New crust is continuously being formed at ___________ therefore the age of the crust is essentially 0, and as you move away the age of the seafloor becomes progressively older

answer

mid-ocean ridges

question

plate boundaries where two plates collide with one another

answer

convergent plate boundaries

question

compressional stresses and reverse faults

answer

convergent plate boundaries

question

denser crust sinks below less dense crust in a ________.

answer

subduction zone

question

older, cooler, and denser oceanic crust is subducted beneath younger, warmer, and more buoyant oceanic crust

answer

ocean-ocean

question

minerals that compose oceanic rocks are more dense than those that make up continental rocks so this occurs

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ocean-continent

question

deep depression forms parallel to the subduction zone, deepest parts of the ocean floor

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trench

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earthquakes will occur from the earth's surface down to a depth of 700 km in the boundary between the subducting and overriding plate

answer

wadati-benioff zone

question

as oceanic plates subduct, heat is produced by friction and the minerals in the crust change form and release water. as a result, a portion of the material in the downgoing slab and in the overlying mantle melts and _____ is produced.

answer

magma

question

molten rock inside the earth, less dense than the surrounding rock and will rise towards the earth's surgace

answer

magma

question

arcuate chains of volcanoes in the ocean basins

answer

island arc

question

chains of volcanoes on the continents will form if this process occurs beneath continental crust

answer

continental arcs

question

really big mountains will be formed at the plate boundary. one plate won't be large enough to cause one plate to subduct beneath the other

answer

continent-continent

question

two plates move past each other horizontally - large shear stresses result in strike-slip faults, link segments of divergent plate boundaries at mid-ocean ridges

answer

transform plate boundary

question

regions of volcanic activity in the interior of a lithospheric plate away from the plate boundaries or major faults

answer

hot spots

question

formed above hot plumes of magma from the mantle that rise toward the earth's surface because of their decreased buoyancy

answer

hot spots

question

1km=1000m=100,000cm=1,000,000mm 1 in = 2.54cm 1.6 km = 1 mile

answer

metric system

question

the study of the earth's past magnetic field as it is recorded in the rocks

answer

paleomagnetism

question

a rock sample can acquire and hold the direction of the magnetic field that existed at the time and place the rock was formed

answer

fossil magnetic remanence of the rock

question

about 600ºC

answer

curie point

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magnetite crystals in the rock cannot be magnetized

answer

above the curie point

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magnetite crystals will acquire a direction of magnetization parallel to the surrounding earth's field

answer

below the curie point

question

earth's magnetic field is generated as if there were a giant bar magnet placed at the earth's interior and slightly inclined from the rotational axis

answer

dipole

question

angle between the magnetic field vector and the surface of the earth

answer

inclination

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angle between the horizontal component of the magnetic field vector and geographic north

answer

declination

question

force per unit area

answer

stress

question

newtons per square meter

answer

earth's stress is measured in

question

stress that acts perpendicular or 90º to that plane

answer

normal stress acting on a plane

question

the stress acting parallel to a plane

answer

shear stress

question

direction of maximum compressive normal stress, zero shear stress

answer

sigma 1 (maximum principle stress direction)

question

smallest normal stress value, still a direction of zero shear stress

answer

sigma 3 (minimum principle stress direction)

question

perpendicular to both sigma 1 and sigma 3

answer

sigma 2 (intermediate stress direction)

question

large earthquakes always occur on pre-existing planes called ______.

answer

faults

question

line where the fault plane intersects the earth's surface

answer

fault trace

question

orientation of the fault trace with respect to the north i.e. the angle between the fault trace and the north

answer

strike

question

angle between the earth's surface and the fault plane measured at right angles to the strike

answer

dip

question

relative movement across the fault is in the direction of the dip i.e. up and down the plane

answer

dip slip

question

hanging wall moves down relative to the footwall; extend crust

answer

normal faulting

question

hanging wall moves up relative to the footwall; shorten crust

answer

reverse (thrust) faulting

question

tensional forces stretch a rock and tend to pull it apart, such as at a rift zone or mid-ocean ridge

answer

normal faulting causes

question

compressive forces squeeze and shorten a rock, such as at a continent continent collision or a subduction zone

answer

reverse faulting causes

question

form from shear stresses and cause blocks of rock to move past each other horizontally, SA fault

answer

strike slip faults causes

question

when one plate moves to the right relative to the other

answer

right lateral strike slip faults

question

when one plate moves to the left relative to the other

answer

left lateral strike slip faults

question

theres a relationship between the orientations of the principle stress directions near the surface of the Earth and the type of faulting we observe

answer

anderson's theory of faulting

question

a subduction zone formed off the west coast of the north american plate

answer

sierra nevada mts

question

28 million years ago, the collision of the pacific plate and north american plate cause the suduction zone along the coast to cease and the two plates began to slide past each other - right lateral fault

answer

San Andreas transform fault system

question

cliffs commonly associated with dip slip faults where vertical offset has occured

answer

fault scarp

question

faults can develop branches and sub-parallel fractures adjacent to the main fracture that have lesser amounts of displacement

answer

fault zone

question

closed depressions of internal drainage are often found in fault zones, occur where faults bend or sidestep forming echelon fractures

answer

sag ponds

question

where failure of rocks occurs

answer

rupture surface

question

fault that has had surface displacement within holocene time

answer

active fault

question

about the last 11,000 years

answer

holocene time

question

San Andreas, San Jacinto, Hayward, Garlock, Newport-Inglewood, Raymond Hill, and Whittier

answer

active faults in CA

question

followed 1971 San Fernando EQ - required compiling of maps delineating active fault zones, local governments can regulate construction for human occupancy across an active fault trace, perspective buyers must be notified that their property is on an active fault

answer

SSZ Act

question

study of ancient earthquakes

answer

paleoseismology

question

paleoseismologists dig trenches across recent fault traces and then study the walls of the trenches for evidence of earlier fault ruptures

answer

how to study ancient earthquakes

question

if a layer is cut by a fault, that layer must be older than the fault

answer

cross cutting relations

question

how to yield absolute ages of layers involved

answer

carbon-14 dating

question

average time between each earthquake

answer

recurrence interval

question

the velocities of the different frequencies in the glass are different

answer

snells law

question

record the travel time of the waves which return to the surface and since the distance from the sources is known the velocity of the reflected and refracted waves can be determined

answer

seismometers

question

faults that only rupture in the subsurface

answer

blind faults

question

a recording of ground motion at a seismic station during some time period

answer

seismogram

question

the place at which the earthquake rupture begins; underground focus point of an earthquake

answer

hypocenter

question

time at which the earthquake rupture begins

answer

origin time

question

a measure of the degree of shaking at a certain location during an earthquake

answer

intensity

question

closed intensity scale measured from I to XII, depends on location relative to hypocenter

answer

MMI Scale

question

contoured map showing regions of equal intensity of shaking

answer

isoseismal map

question

measures the size or the total energy release of an earthquake, open scale (-infinity, infinity)

answer

magnitude

question

a logarithmic scale that assesses the sizes of earthquakes by powers of 10

answer

Richter scale

question

the logarithm of the maximum seismic body wave amplitude recorded on a standard type of seismograph at a distance of 100 km from the epicenter

answer

local magnitude Ml

question

the duration of perceptible oscillation as recorded on a seismogram from a local earthquake can be conveniently converted to a ___________.

answer

duration magnitude Md

question

the number of cycles the wave goes through in a certain amount of time

answer

frequency

question

when the passing seismic waves have a frequency that matches the natural frequency of the building

answer

resonance

question

the condition of soil and unconsolidated sediments losing their resistance to shearing; a situation when water that is located in pore spaces between sand grains is mobilized due to shaking and essentially turns the sediment into a fluid

answer

liquefaction

question

supported by a series of bearing pads which are placed between the building and the building's foundation

answer

base isolation

question

made from layers of rubber sandwiched together with layers of steel

answer

lead-rubber bearings

question

piles of rubble - brick, stone, adobe

answer

unreinforced masonry

question

not enough steel especially confinement steel (steel rebar wrapped around vertical rebar)

answer

non-ductile steel-reinforced concrete

question

optimal building type

answer

steel frame

question

when properly built will ride out the earthquake, more of the damage comes from flying objects

answer

wood frame

question

Mw 6.4; arguably the most important eq in history because it mandated schools in LA be earthquake resistant - field act

answer

1933 Long Beach

question

Mw 6.9; first eq to be recorded by strong ground motion seismometers, showed 0.3g

answer

1940 Imperial Valley

question

increase of 1 second in frequency for every _______.

answer

10 stories

question

Mw 6.9, used soviet style buildings with L brackets connecting beams to walls

answer

1988 Spitak Armenia

question

Mw 8.5, 10-20 story buildings collapsing, matched resonance frequency, sedimentary basin

answer

1985 Mexico City

question

Mw 6.5, most buildings were non-ductile steel reinforced concrete buildings

answer

1971 San Fernando

question

most important in dictating whether or not a building will hold

answer

90 degree column to beam connection

question

ideal crimping angle for confinement rebar

answer

135 degrees

question

if a column exceeds _____, it is unable to resist gravity

answer

10 degrees

question

philosophy of earthquake prediction based on previous history

answer

statistics and probabilities

question

philosophy of earthquake prediction based on looking for precursors

answer

deterministic/physical

question

Mw 9.4, largest earthquake ever recorded

answer

1960 Chile

question

Mw 7.8

answer

1857 Fort Tejon

question

Mw 6.9

answer

1995 Kobe

question

Mw 7.9, epicenter in the heart of the city

answer

1906 San Francisco

question

Mw 6.9, during the world series

answer

1989 Loma Prieta

question

Mw 6.7, destructive eq in LA area

answer

1994 Northridge

question

____ of oceanic lithosphere is mantle

answer

95%

question

____ of oceanic lithosphere is crust

answer

5%

question

what is the outer core made of

answer

iron and nickel

question

what is the inner core made of

answer

iron and nickel

question

outer core is

answer

liquid

question

inner core is

answer

solid

question

most damage from an earthquake a few tens of miles away comes from ______

answer

s waves

question

body waves have a ________

answer

high frequency

question

in partially molten material, p waves __________

answer

slow down

question

most effective way to measure earthquakes

answer

moment magnitude scale

question

the lithosphere/asthenosphere boundary is ______

answer

mechanical

question

results from S waves being stopped entirely by the liquid core and P waves being bent by the liquid core

answer

s-wave shadow zone

question

deepest San Andreas ruptures are ____ depth

answer

15 km

question

how long do tsunami periods last?

answer

15 minutes

question

fault displacement has a factor of _____

answer

3.2

question

relative motion between the Pacific and North American plates is ______

answer

5 cm

question

closest fault to USC

answer

Puente Hills blind thrust fault

question

most important control of tectonic plates

answer

slab pull

question

magma on convergent boundaries forms through _______

answer

dehydration melting

question

magma on oceanic spreading centers forms through ______

answer

decompression melting

question

isotropic stress is the __________

answer

same in all directions

question

oceanic plates are rich in _______

answer

iron and magnesium

question

reason for large hills in LA

answer

East West striking reverse faults

question

_____ of plate boundary motion is caused by the Eastern California shear zone

answer

20%

question

in normal faults _____ is vertical

answer

sigma 1

question

1 mile = ____ km

answer

1.6

question

_____ of total seismic energy occurs on the Pacific Rim

answer

90%

question

how old is the earth?

answer

4.6 billion

question

depth of the moho

answer

30-70 km

question

depth of asthenosphere lithosphere boundary

answer

100 km

question

depth of deepest earthquakes

answer

700 km

question

depth of olivine to spinel boundary

answer

400 km

question

earth's radius

answer

6371 km

question

how thick is the earth's mantle

answer

2900 km

question

earth's core radius

answer

3458 km

question

order of polymorphic phase change

answer

olivine, spinel, perovskite

question

locating EQ with s-p travel time: 1 sec

answer

4 km

question

locating EQ with s-p travel time: 2 sec

answer

10 km

question

locating EQ with s-p travel time: 10 sec

answer

80 km

question

locating EQ with s-p travel time: 18 sec

answer

150 km

question

Mw 7.6 manifestation of the release pressure that built up in the CA shear zone

answer

1872 Owens Valley

question

the first time that a law had been passed to require buildings that had to be built to withstand earthquakes

answer

field act

question

Mw 9.0 earthquake and tsunami killed 16,000

answer

2011 Tohohku

question

Mw 7.3 only earthquake "ever" predicted by people

answer

1975 Haicheng

question

Mw 7.8 no foreshocks, flattened the city

answer

1976 Tangshan

question

Mw 6.1 foreshock of Landers earthquake

answer

1992 Joshua Tree

question

Mw 7.1 west of Christchurch, occurred out in farm country

answer

2010 Darfield

question

Mw 6.3 worst case scenario, occurred directly beneath the city

answer

2011 Christchurch

question

original great San Francisco earthquake

answer

1868 Hayward

question

earthquake that destroyed San Juan Capistrano mission

answer

1812 Wrightwood

question

Mw 9.2 killed 250,000

answer

2004 Sumatra

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