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63 Cards in this Set
- Front
- Back
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What are earthquakes? |
Vibrations of Earth produced by the rapid release of energy |
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What are most earthquakes the result of? |
Slippage along faults |
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What is a fault? |
A fracture in the ground where displacement (slippage) occurs |
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What is a fault scarp? |
Exposed surface of a fault |
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What is the original point of rupture along a fault called? |
focus |
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What is the surface point directly above the focus called? |
epicenter |
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What is the location of the fault on the earth's surface called? |
fault trace |
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What is the theory that explains why earthquakes occur called? |
elastic rebound theory |
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What does adding stress to rocks cause them to do? |
strain (change their shape or size) |
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What happens when stress on rocks becomes too great? |
the rocks rupture |
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What is the energy from a rupture converted into? |
seismic waves |
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What does a typical earthquake cycle depend on? |
The rate stress is applied and the strength of the rocks |
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What is the study of earthquakes called? |
seismology |
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What is the principle of inertia? |
An item at rest will stay at rest until an outside force is acted upon it |
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What is another word for inertia? |
laziness |
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Upon what principle do all seismic instruments work? |
inertia |
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What is an instrument used to record earthquakes? |
seismograph |
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What is a record of an earthquake event? |
seismogram |
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How does the P-wave travel through the earth? |
compression 13000 mph |
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How does the S-wave travel through the earth? |
a shearing motion 8000 mph |
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What waves have a longer wavelength? |
surface waves L-waves |
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What are the slowest traveling waves? |
surface waves |
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What is the time lag between the first arrive of the P-wave and the first arrive of the S-wave proportional to? |
The distance between the earthquake epicenter and the recording station |
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What can one calculate from a seismograph? |
The distance to the epicenter, but not the exact direction |
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How much data from seismic stations does it take to locate the epicenter of an earthquake? |
The data from a minimum of three seismic stations |
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Where does most earthquake activity happen? |
Along the Circus-Pacific belt |
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How many levels of intensity are defined on the Modified Mercalli Scale? |
12 |
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What is liquefaction? |
The flowing of a saturated soil due to the inability of water to compact |
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When does wave amplification occur? |
When seismic waves slow down |
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What determines the natural period or resonance of a high rise building? |
The height of the building |
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What determines the magnitude of an earthquake? |
The amplitude of the shaking and the distance to the epicenter |
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By how much will a 10 fold increase in amplitude increase the magnitude number? |
By 1 |
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All things equal, how much greater will the amplitude of a 7.0 earthquake be than the amplitude of a 5.0 earthquake? |
100 times |
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How many times more energy does an 8.0 earthquake release than a 7.0? |
32 |
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How many times more energy does a 6.0 earthquake release than a 5.0? |
32 |
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How many times more energy does a 7.0 earthquake release than a 5.0? |
1000 |
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How many times more energy does an 8.0 earthquake release than a 5.0? |
32000 |
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In what range on the scale do major earthquakes occur? |
7.0-7.9 |
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What rating on the scale are great earthquakes? |
8.0+ |
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From what are most tsunami generated? |
rapid movement of the seafloor |
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What happens to the speed of a tsunami as it nears shore? |
it slows |
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What happens to the height of a tsunami as it nears shore? |
it builds |
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What happens to the wavelength of a tsunami as it nears shore? |
it shortens |
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What are seismic gaps? |
seismically quiet regions where stress is building |
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What is a nebula? |
The gas and dust cloud from an exploded star |
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What is the material our solar system is formed from thought to be? |
nebular |
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What pulled the nebular material together into the sun, planets, etc? |
gravity |
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What allowed the earth to differentiate very early in Earth's history? |
melting |
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What are the Earth's layer, from the inside out? |
inner core, outer core, mantle, crust |
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Of what is the earth's core thought to be mostly composed? |
iron |
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Of what is the mantle believed to be composed? |
ultramafic rock |
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What happens to seismic waves as they enter deeper, more dense rocks? |
they refract (change direction) |
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How do seismic waves travel through the earth? Why? |
in a curved path due to multiple refractions |
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What are distinct seismic boundaries called? |
seismic discontinuities |
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What is the seismic discontinuity between the crust and the mantle called? |
the Moho |
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Through what can't S-waves travel? |
fluids |
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What do P-waves do, because the outer core is liquid? |
they slow way down |
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What does the slowing down of P-waves cause? Which results in what? |
A large refraction A P-wave shadow zone |
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As what does a P-wave shadow zone appear around the earth? |
a ring |
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What causes an S-wave shadow zone? |
S-waves' inability to enter the outer core |
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What does the S-wave shadow zone include? |
The P-wave shadow zone plus all the area inside the ring |
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Compositionally, into what can the earth be separated? |
the iron core, the ultramafic mantle, the mafic oceanic crust, the felsic to intermediate continental crust |
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From inside to out, what do the physical layers of the earth include? |
the solid inner core, the liquid outer core, the solid lower mantle, the very soft asthenosphere, and the solid lithosphere |
