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69 Cards in this Set
- Front
- Back
Which earthquake did more damage Kobe or Northridge and why?
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Kobe because earthquake epicenter hit main populated city
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What are the causes of earthquakes?
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-release of strain in rocks along fault
-most associated with plate tectonic movement -point of rupture or shift marks focus |
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What is the epicenter?
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point on earth's surface above focus
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True or false: Most earthquakes are followed by aftershocks as rocks continue to move.
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True
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What are seismic waves?
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-transmission of energy form earthquake through rock in wave form
-body waves - "P" waves for primary and "S" waves for shear |
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What type of motion do shear waves create and are they faster or slower than p waves?
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back and forth; half the speed of p waves
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Can s waves be transmitted through a liquid?
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no
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What is a basic seismometer?
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weight hangs free in space while drum which is attaced to rock moves within earthquake waves
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What is a moern seismometers?
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use earth geophones that can detect very small movements as well as large
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What are the scales used to describe intensity of movement from earthquakes?
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-mercalli (I-XII scale)
-richter -moment-magnitude |
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Which earthquake did more damage Kobe or Northridge and why?
|
Kobe because earthquake epicenter hit main populated city
|
|
What are the causes of earthquakes?
|
-release of strain in rocks along fault
-most associated with plate tectonic movement -point of rupture or shift marks focus |
|
What is the epicenter?
|
point on earth's surface above focus
|
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True or false: Most earthquakes are followed by aftershocks as rocks continue to move.
|
True
|
|
What are seismic waves?
|
-transmission of energy form earthquake through rock in wave form
-body waves - "P" waves for primary and "S" waves for shear |
|
What type of motion do shear waves create and are they faster or slower than p waves?
|
back and forth; half the speed of p waves
|
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Can s waves be transmitted through a liquid?
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no
|
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What is a basic seismometer?
|
weight hangs free in space while drum which is attaced to rock moves within earthquake waves
|
|
What is a moern seismometers?
|
use earth geophones that can detect very small movements as well as large
|
|
What are the scales used to describe intensity of movement from earthquakes?
|
-mercalli (I-XII scale)
-richter -moment-magnitude |
|
Which earthquake did more damage Kobe or Northridge and why?
|
Kobe because earthquake epicenter hit main populated city
|
|
What are the causes of earthquakes?
|
-release of strain in rocks along fault
-most associated with plate tectonic movement -point of rupture or shift marks focus |
|
What is the epicenter?
|
point on earth's surface above focus
|
|
True or false: Most earthquakes are followed by aftershocks as rocks continue to move.
|
True
|
|
What are seismic waves?
|
-transmission of energy form earthquake through rock in wave form
-body waves - "P" waves for primary and "S" waves for shear |
|
What type of motion do shear waves create and are they faster or slower than p waves?
|
back and forth; half the speed of p waves
|
|
Can s waves be transmitted through a liquid?
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no
|
|
What is a basic seismometer?
|
weight hangs free in space while drum which is attaced to rock moves within earthquake waves
|
|
What is a moern seismometers?
|
use earth geophones that can detect very small movements as well as large
|
|
What are the scales used to describe intensity of movement from earthquakes?
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-mercalli (I-XII scale)
-richter -moment-magnitude |
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What is the moment-magnitude scale more suited to measure?
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energy released rather than effect which can vary depending on rock thru which waves are passing (-2 to 10 scale)
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What scale are most earthquakes reported in popular press as?
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richter scale (1.0 to 8.0 scale) - not a linear scale (4.0 is not twice as strong as 2.0)
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What have advances in earthquake detection and measurements been driven by?
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need to monitor for nuclear tests
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What caused most of the damage in the 1906 San Francisco earthquake? and how much movement did it cause?
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-fires
-7 meters or 25 feet |
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What earthquake in 1989 represented movement on the San Andreas Fault zone south of san francisco?
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Loma-Prieta Earthquake
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What is liquefaction?
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occurs when the grains in a layer of wet, fine-grained sediment shake during an earthquake. (in 1964, the clay layer beneath the entire Turnagain Heights area of Anchorage, Alaska, liquefied, resulting in a chaotic landscape of jumbled homes and asphalt blocks)
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Where are the world's priniciple earthquake zones?
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-plate boundaries
-80% energy in Pacific Rim region -depth dependent on type of plate boundary -shallow-rift and continental plate -deep subduction -intraplate -generally less energy -exceptions- New Madrid and 1998 ocean floor south of Australia -generally shallow (why? - not known - old faults, unloading?) |
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What type of foci are associated with divergent zones?
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shallow earthquake foci
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What type of foci are associated with subduction zones?
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progressively deeper earthquake foci
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What type of foci are associated with continental collision zones?
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shallow earthquake foci
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What type of foci are associated with intraplate continental rift zones?
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shallow earthquake foci
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What type of foci are associated with transform boundaries?
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shallow earthquake foci
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What are seismic gaps?
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no activity happens here, even though it is in a prime area
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Describe tsunami/ tidal waves.
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-at sea barely perceptible
-crests 100 miles apart -velocities of 800 km or 500 miles/hour -crest heights less than 1 meter -dramatic effects on reaching shore |
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What are the long-term factors for earthquake predictions?
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-periodicity
-seismic gaps -rate of movement of plates -movement builds up stress |
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What are the short-term factors for earthquake predictions?
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-cracking or distancy - foreshocks
-change in seismic V -water level changes -electrical conductivity -animal activity |
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True or false earthquake prediction is just as good as volcanic eruptions.
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False
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What are some things plate tectonics determine?
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-climate by controlling distribution of land masses and their latitudes
-location of landmasses determines oceanic circulation -mountains block and direct air mass movement -volcanic activity produced the N that makes up 80% of our atmosphere and released water vapor that condensed to contribute to our oceans |
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What does Earth's lithosphere consist of?
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60 miles in thickness of rigid plates
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True or false: Center of plates tend to be geologically stable.
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True
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True or false: Fossils, rocks, and climates match across continents where they were once joined.
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True
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What did magnetometers towed by ships detect?
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changes in strength of Earth's magnetic field. plotting of these changes showed stripes of weaker and stronger fields
-early 1960's Vine and Drummond proposed stripes represent evidence of searfloor spreading at mid-ocean ridges |
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What happens as basalt cools?
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its crystallizing magnetic minerals line up with current Earth's magnetic field
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What does dating basalt in given stripe yield?
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rates of movement
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What plates move the fastest each year?
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pacific, nazca, cocos, and australian-indian plates
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What are the slowest moving plates?
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north and south america, eurasian, and antarctic
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What all have refined view of the ocean bottom?
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-deep diving submersides
-ocean drilling -gravitational measurements by satellites -sonar imaging |
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What are the 3 mechanisms for oceanic plate movement?
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-ridge push
-slab pull -plate sliding |
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What is ridge push?
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rising magma at divergent plate boundaries push plates apart
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What is slab pull?
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subducting lithosphere becomes more dense as felsic components rise due to partial melting, causing it to sink and pull plates sideways
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What is plate sliding?
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lithosphere of subducting plate sides down slope created by elevated mid-ocean ridge ("convention current" - helps pull apart and collide)
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What is convention current?
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helps pull apart and collide
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What are the ores folded in mountain rocks (mid-ocean ridges)?
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Cu, Fe, Zn, Co, Ag, Cd
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What are "black smokers"? (mid-ocean ridges)
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-consist of hot plumes of mineral-rich water vented at volcanically active regions of seafloor
-accumulations of precipitated minerals form chimney-like structures - "smoke" - consists of hot water and particles of iron -bacteria can form around hydrothermal vents derive energy from heat generated chemical reactions |
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Why do the Himalayas have no volcanoes?
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one plate is not subducting
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What are the basic components of continents?
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shields (haven't changed in billion years), continental platform (thin veneer of younger sedimentary rock), together form craton
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What happens because continental rock (less dense) doesn't subduct?
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once formed becomes permanent part of Earth's crust
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Describe plate tectonics.
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-full-fledged theory
-"mountains of evidence" -most straight forward answer is probably the right answer |
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What are the 3 types of plate boundaries?
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-divergent
-convergent -transform |