GEOL 240 Final Study Guide

GEOL 240 Final Study Guide - GEOL240FinalStudyGuide 22:16

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GEOL 240 Final Study Guide 22:16 Aug 26-Where Earthquakes Occur and Why-Plate Tectonics Powers of 10 Age of earth and solar system o The universe is about 12 billion years old o The age of the earth and solar system is about 4.6 Ga Ga=billions of years Ma=millions of years o Date meteorites  Carbonaceous chondrites o Primitive stony meteorites o Used to find age of earth/solar system Radioactive decay dating o Called radiometric dating o 1940’s and 1950’s of absolute time scale o the radioactive date is based on a ratio of parent element to stable  daughter elements Half life o Used for determining radioactive decay Paradigm shift o An overarching concept/idea that explains everything about something (i.e.  Plate tectonics) Global eq distribution
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o Eqs don’t occur everywhere on the earth with equal frequency o “earthquake belts” is where most eqs occur o 90% of energy released in eqs appears around the ring of fire of the  Pacific ocean Relationship between bathymetry and eqs o Bathymetry:  depth to /topography of sea floor Wadati-Benioff zones o Deep eqs o A zone within the convergent plate boundary with seismic activity up to  700 km deep and deepest known volcanic activity As the ocean subducts along the continent it forms trenches (deepest  known) Form volcanic arc (South America, Washington, Seattle…) Island arcs Aug 31-Plate Tectonics-The Evidence Lithosphere vs. aesthenosphere o Lithospheric plates move relative to one another by sliding on a weaker  softer layer called the aesthenosphere (in plate tectonics) o Eq bets define edges of a dozen tectonic plates Plates are about 100 km thick and are made of lithosphere Examples of spreading centers o Mid-Atlantic Ridge o East African Ridge o East Pacific Rise
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Olduvai George and early Hominids Eq occurrence along convergent margins o Usually one plate slides underneath the other=subduction plate Wadati-Benioff zones Max depths eqs to 670 km Island arc Depth to melting Why melting occurs during subduction Sept 2-Plate Tectonics-The Mechanism:  Sea-Floor Spreading and Subduction Subduction cont. Convergent vs. divergent magma composition and viscosity Different types and behavior of volcanoes Slab pull vs. passive spreading ridge opening Transform boundaries (SAF as example) Fracture zones vs. transform faults Motion directions o Dynamic nature of spreading ridge vs. passive marker such as a road or  fence Continental vs. oceanic lithosphere Intro to litho/aesthenosphere vs. crust/mantle core  Continent-continent collision
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Indian seismic risk Sept 7-Plate Tectonics-Paleomagetism
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This note was uploaded on 02/06/2011 for the course 2010 39550 taught by Professor Piterbarg during the Fall '10 term at USC.

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GEOL 240 Final Study Guide - GEOL240FinalStudyGuide 22:16

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