Earth Science Exam 2

Earth Science Exam 2 - Earth Science Exam 2...

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Earth Science Exam 2 Earthquakes/Earth’s Interior Fault: -where earthquake occurs -shows movement Order: 1. stress begins, fault is locked 2. stress builds, deformation continues 3. fault slips, stress is released, rocks = unstressed dimensions Seismic time in between quakes quiescence: Epicenter: place on Earth directly above the quake (focus) Focus: place underground where quake occurs Types of seismic waves: 1.Compressional/ -also called P-waves primary waves: -1 st to be received by recording station because they move faster -moves in compression and extension like a slinky -parallel to direction of propagation -travel in solid and liquid 2. Secondary/ -also called S-waves sheer waves: -2 nd to be received by recording station -moves up and down -perpendicular to direction of propagation -cannot travel through liquid (only solid) 3. Surface/love -on surface of Earth waves: -shows retrograde orbital (rolls) -responsible for the most amount of damage Seismometer: spring loaded weight with coils that records quake (with time) Seismograph: the print out of this recording Magnitude: measurement/calculations of how much energy is released Richter Scale: -measures magnitude (logarithmic scale) -above 6 or 7 = grade earthquake -9 is the maximum we have ever seen Mercalli Intensity-measures the intensity of an earthquake Scale: -can be subjective -from 1-12 (not felt to total damage) Seismographic -you need 3 to locate the epicenter (triangular distance to…) Recording -determine the distance through S-P interval (arrival of P, arrival of S) Stations: -with distance, the S-P interval increases -the plotting of epicenters has outlined the plate boundaries (most earthquakes occur along plate boundaries) Active plate -large, deep earthquakes boundary: -subduction zone Passive plate -shallow, not as large quakes boundary: Earth’s interior: -P and S waves give us the indirect data of Earth’s interior -P = small shadow zones due to bending in core -S = large, almost ½ circle shadow zone due to not going through the core (which is liquid) Plate Tectonics Give us: -mountains -climate change -dynamic process that interacts with the atmosphere, ocean, and land Pre Theories: 1. 1912 theory of continental drift (Alfred Wegener) 2. theory of seafloor spreading (1960’s – Harry Hess and Robert Ditz) 3. theory of plate tectonics
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Evidence for 1. geography – jigsaw puzzle (super continent Pangaea, tear newspaper apart, put back continental drift: together and you can read the lines…) * Pangaea – in 1965 Ballards did a computer simulation and the best fit is 2,000m depth 2. paleontology – fossils, rock type (core) 3. structural geology – mountain ranges 4. glaciers – trace glacial deposits (at a time the world may have been one major ice sheet) 5. paleo climates – evidence for ancient climates from coral reefs, coal deposits, and salt deposits Theory of sea- -geo-poetry floor spreading: -left seafloor tracker on and saw underwater mountains, trenches, etc. -crust formation is equal to crust deformation (created at mountains, destroyed at
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This note was uploaded on 04/08/2008 for the course ES 211N taught by Professor Thompson during the Fall '07 term at Eckerd.

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Earth Science Exam 2 - Earth Science Exam 2...

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