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16 Cards in this Set
- Front
- Back
Definition and Cause of Earthquakes
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Def: a release of energy in the crust; explained by the Elastic Rebound Theory
Cause: meteor impact, train, movement of lithospheric plates |
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Focus:
Shallow Intermediate Deep |
The point where seismic energy (waves) originate
S: 0-70km; found @ convergent boundaries I: 70-300km; found @ divergent boundaries D: 300-700km; found @ divergent boundaries |
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Fault
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Any fracture in the Earth's crust where movement occurs; faults can be plate boundaries
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Epicenter
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Point on the Earth's surface about the focus
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Seismic Waves
Primary |
Travel as compressional energy (push-pull); fastest traveling seismic wave able to travel through all mediums
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Seismic Waves
Secondary |
Travel as shear energy (side to side); slower than P waves and only able to travel in SOLIDS; affected particles move at right angles to the direction of the wave
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Seismic Waves
Longitudinal |
Last seismic wave to arrive; a local product of the P and S waves; affected particles move in a circular motion as the wave passes--CAUSE THE MOST DESTRUCTION
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All seismic waves increase their speed and strength as the rock they trave through...
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...increases in density and rigidity
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Earthquake Magnitudes (based on logarithms)
Mercalli Scale |
Based on ground shaking and foundation failure
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Earthquake Magnitudes (based on logarithms)
Richter Scale |
Every increase of 1 on the scale translates into an increase of 32 in seismic wave energy (For example: an earthquake with a magnitude of 5.5 is 32 timres stronger that an earthquake of magnitude 4.5)
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Earthquake Magnitudes (based on logarithms)
Seismic Moment Scale |
Not as easy to measure, but it does give an accurate indicator of the total energy released in an earthquake (not just wave energy)
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Earthquake Prediction:
P-wave velocities increase before a major quake...why? |
Here's why...
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Earthquake Prediction:
Elevation changes can be detected and measured before a major tremor...why? |
Here's why...
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Earthquake Prediction:
Radon gas in well water... |
...increases before a major quake
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Earthquake Prediction:
Lasers are used to detect motion along active faults--If there is no motion... |
...there is
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Earthquake Prediction:
Seismic Gap Method |
Uses known periods of time between quakes as an indicator; this method is based on past quake patterns and power laws
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