GLG - Earthquakes and Earths Interior Two types of...

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Earthquakes and Earth’s Interior Two types of Earthquake waves Body Waves : travel through solid body of the Earth. Surface Waves : travel along the ground surface. Body waves: Capable of moving rock a few millimeters or centimeters. P – waves : Parallel to direction of movement; also called primary waves. S – waves : Perpendicular to the direction of movement; also called secondary or shear waves. Surface waves: Capable of moving rock a few centimeters to meters. Produce rolling/swaying motion of the ground. - Rayleigh Waves (R-waves) - Love Waves (L-waves) Seismic Data Interpretation Rule #1 Denser material transmits waves faster. Rule #2 S-waves cannot travel through a liquid, but P-waves can. SUMMARY: The earth is zoned both chemically and mechanically. Chemical zoning is one result of Earth’s early differentiation. Mechanical zoning results from the superposition of depth-wise pressure and temperature differences on the chemical layering. The brittle lithosphere floats on top of the plastic asthenosphere. The lithosphere experiences low temperature and pressure conditions and thus tends to respond in a brittle fashion to stress. The asthenosphere experiences high temperature and moderate pressure conditions and thus tends to exhibit a ductile response when deformed. The lithosphere is composed of felsic (granite) to mafic (basalt) rocks and is less dense than the asthenosphere, which is composed of ultramafic rocks (peridotite). Continental lithosphere is less dense and thicker than oceanic lithosphere and thus floats higher on the asthenosphere than does denser, thinner oceanic lithosphere. The lithosphere is broken into several larger and smaller sections (plates) that shift around over time. Plate Tectonics/Mantel Convection Earth Interior Review Mantle is the largest layer Core-solid, very dense Differentiation explains the distribution of elements and the different densities found among the layers P wave velocities Abrupt changes in seismic velocities and echos reveal boundaries between different materials
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P waves travel best through high density material P waves are deflected every time they encounter a different density substance—this explains the appearance of shadow zones Phases and Behaviors of layers Crust- solid phase and a rigid behavior. This means that under force the object breaks and cracks (ruler example) Asthenosphere-solid/elastic- this means that it is partially molten (like soup) with some melted and solid particles. So, under force this behaves more elastic like and stretches (think silly putty). Convection-what causes it? Heat from core radiating to Earth surface Radioactive decay of elements within Earth’s layers give off energy Convection happens because of the temperature difference created by the heat Warm rises, cool falls Radioactive Decay Radioactive Isotopes are atoms with a different number of neutrons than a usual atom,
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This note was uploaded on 11/15/2011 for the course GLG 111 taught by Professor Kuentz during the Fall '05 term at Miami University.

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GLG - Earthquakes and Earths Interior Two types of...

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