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31 Cards in this Set
- Front
- Back
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what is an earthquake?
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caused by
1. volcanic activity 2. meteorite impact 3. undersea landslides 4. nuclear bombs 5. FAULTS |
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law of original horizontality
law of original continuity law of superposition |
H- all sediments are deposited in layers
C- layers will continue unless end against a topographic high/gradial change S- youngest rocks on top |
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dip
strike |
dip- degree of inclination of from tilted layer
strike- horizontal line on tilted layer |
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Types of Faults?
*direction of movement *kind of stress *kind of faults specific |
1. Dip-Slip:
*normal and reverse faults *vertical movement 2. Strike-Slip *horizontal movement *left/right lateral faults 3. Transform faults *horizontal movement, sliding past each other, EXCEPT at two spreading centers then it is strike-slip |
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types of stress with
1. normal faults 2. reverse faults 3. left lateral 4. right lateral |
1. tension/extensional
2. compressional 3. compression - mountains, uplift 4. extensional - valleys, basins |
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____ detects waves and a ____ records them
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seismometer- stays still while earthquake moves earth and records N-S, E-W and up down components
seismograph |
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amplitude
wavelength frequency period |
amplitude- displacement of wave
wavelength- from peak to peak frequency- # waves/second = hertz period- time between waves = 1/frequency |
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body waves verses surface waves
*fastest, periods, |
P- can travel through anything, fastest (1.7x faster than S)
S- can travel through solids, reflect at other materials P & S - shorter periods than L/R, dont have straight path (depends on materials); S-P = distance from epicenter Love- like S wave, faster than R Rayleigh- longer period, far distance, elliptcal movement |
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Maule, Chile earthquake
*what plates? *action of plates *date/magnitude *converging rate |
8.8 in 2010
Nazca and South American Plate, Nazca subducting at 8cm/year at Peru-Chile trench |
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waves _____ in athenosphere and in the _____ part of the mantle and slow down at _____ part of the mantle.
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speed up, inner core, outer core
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Richter Scale
Body Wave Scale Surface Wave Scale *abbreviation *uses |
richter- only for CA/based on energy release
Mb- uses amps of p waves 1-10 sec periods Ms- uses rayleigh w/ 18-22 sec periods |
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Moment Magnitude Scale
*abbreviation *use *example of highest |
Mw/Mo
amount of energy release, uses entire waveform rock strenght X rupture area X slip displacement Chile 1960, 10.0 |
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a short rupture and duration = ___ freqency waves ____ (close/far)
a long rupture and duration = ____ frequency waves ____ (close far) |
= high, close
= low, far |
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Mercalli Scale assess _____
example (the letters to spell one are in the second word...) |
assess earthquakes based on damage
ex: San Fernando Valley, CA 1971 >soft sediment caused a lot of damage, bulls eye shape, dam sunk four feet above water - couldve been really bad |
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ways to make good, sturdy buildings:
ex: |
put in structures to help resistance to shear, get rid of resonance by changing height, moving weight to bottom, changing shape, materials and attach foundation
ex: highways (all weight on columns) Tacoma Bridge |
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Tsunamis are caused by
earthquakes occur at ___km/sec and tsunamis occur at ___km/sec and therefore tsunamis are ____. |
vertical change in seafloor (overriding plate in subduction zone cannot pass)
3-6, .2, slower |
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what are seiches? example
what is resonance? |
seiches - oscillating water in a closed body of water... caused by winds/earthqaukes
ex: Hebgen Lake, Montana - 1959 --- two faults moved causing earthquakes, the normal faults caused end of lake to drop down = seiche for 11.5 hrs shifted=quake=tsunami resonance- when frequency of building = freq of waves |
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example of Volcano Caused Tsunami ?
(krazy kats erupt like volcanos and they're eyes are shaped like eights) |
Krakatau, Indonesia - 1883
>eruption caused collapse of mountains, 40 m tsunami - 36000 deaths |
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Landslide caused tsunami
(3) (think: bay rhymes with "haii (hey)" and birds live on that island |
Lituya Bay - 1958
-on fairweather fault, mag 8... collapsed rock caused tsunami Hawaii- island into ocean after flank collapse canary islands- 15000 years ago, mega collapse |
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Western NA Plate History--
how many years ago did the pacific plate contact west coast? two examples (the W in western, turn upside down, and ppl like "fri"ed foods in the west) |
Mexico City- 1985 - 8.1 - 350 km from M.city
- COCO'S plate under NA Good Friday, Alaska - 1964 - 9.2 - 1000 (goooooood) km of segment slipped = 11m lift and 2m subsidence |
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Upcoming pacific N-W quake
*what plates and actions? how do we know it is occuring? when was the last earthquake here? |
Cascada Subduction zone - Juan de Fuca plates under NA plate, we know its continuing because the volcanoes, which are active, cant be active without subduction
1700 mag 7 -- caused tsunami to hit Japan -- know because of Tree rings |
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two examples of when the CA transform fault caused quake
(where szep wants to live in __ years when she grads from law school is last number in year) (transform = transformers = sports) |
san francisco - 1906
-fault shifted UP 6m -this LOCKED fault = stress will build till another rupture loma prieta- 1989 - world series - near 1906 one, fault plane inclined by 70 degrees = shifted pacific plate north and uplifted santa cruz mountains - short rupture (7 sec) |
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when was there a prediction of Loma Prieta? in 2003 there was a ___ percent predicition of a quake in ____
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1988, a year before, showed 30% chance
2003- 62-80% chance of san fran area/socal |
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the San Andreas fault is a ___ fault of the ___ and ___ plate
example (san andreas is two words, so is this one, andrew like to build forts) |
strike-slip ; right-lateral, pacific and NA; 36 km along san andreas ruptured, and about 30 ft on western side had shifted northward, horizontally
COMPRESSION = thrust fault = uplift |
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what is a blind thrust? give example and compare propagation (elizabeth couldve been born blind, if you look really north, you could go blind)
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1994 NorthRidge earthquake - pico blind thrust (also under san fernando)
- had north propagation vs san fernando which has south propagation = direction of prop = where stronger shaking |
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how do basin and ranges form, and on what plate is one located/ area?
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1. hot mantle rises
2. plate stretches apart 3. crust fractures w/ stretching 4. plates rise and thin w/ stretching 5. mountains rise and valleys drop and create basin range topography... in CA/Nevada area on NA plate |
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give example of rupture in western great basin? (owen and miles live west of broughton)
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Owen Valley, CA - 1872
third largest rupture of san fran and tejon |
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Where is the intermountain seismic belt? (Wumi) How long is it, and how wide is it, what does it seperate. 3 examples (one in montana [heb=half), marykate and ashley went to bora bora and wore belts [kate rhymes with eight], you can buy watches in utah)
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Wyoming, Utah, Montana, Idaho
Hebgen Lake, Montana - 1959 Borah Peak, Idaho - 1983 (peak uplifted, valley lowered) Wasatch Fault, Utah - 7 every 350 yrs in Salt Lake City (very dangerous) |
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Intraplate Earthquakes are located in ___ US. main example: (spain is in the center of the world)
how many quakes? largest at what magnitude? why does this area have bad quakes (3 reasons) |
Central US;
New Madrid, Montana - 1811-1812 1. hypocenter below mud/sands = high intensity 2. central us has homogenous, older rocks, which make it harder to impede wave energy 3. reelfoot rift |
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where is the reelfoot rift (Mitka, like minka)? what does it create a linear structure? when was the rift created and why? what kind of rift is it?
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kentucky, illinois, missouri, arkansas tennesee
created a linear structure becauses gravity, magnetism, and seismic waves. created 550 mya from pangea tearing, failed rift, which means there is a zone of weakness that can be reactivated by stress |
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New England Earthquakes (3) (suzie, isabelles sister, and mary lawrence are all older than me) and Charleston, SC earthquake
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boston (when pilgrams landed in 1638) all around 5-6 ma
nyc ^^ st lawrence river valley - coincides with canada's quakes 500 mya rift followed by river.. most active area is Charlevoiz because meteorite impact 350 mya charleston, sc - 1886 sand geysers, most buildings destroyed - waves to michigan, no surface faulting... all bc rocks old |
