4Natural_Disaster_Earthquake_Lecture_Outline.doc

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Department
American Sign Language
Course
AMSL 101
Professor
landau
Semester
Fall

Description
EarthquakesChapter3EarthquakesandTheirDamagesShakingGroundCollapsingBuildingsChapter4EarthquakePredictionandTectonicEnvironmentEarthquakesarevibrationsoftheearthcausedbytheruptureandsuddenmovementofrocksthathavebeenstraineddeformedbeyondtheirelasticlimitTheforcesthatcausedeformationandthebuildupofstrainenergyintherockarereferredtoasstressesEarthquakesoccuralongfaultsFaultsarefracturesinthelithospherewhereregionsofrockmovepasteachotherdisplacedThefocusisthepointonthefaultwhereruptureoccursandthelocationfromwhichseismicwavesarereleasedTheepicenteristhepointontheearthssurfacedirectlyabovethefocusWhenthefaultruptureswavesofenergycalledseismicwavesspreadoutinalldirectionsElasticReboundTheoryTypesofFaultsThemajorityofearthquakes90arecausedbyrocksrupturinginresponsetotectonicstressesatactiveplatemarginsTypesofTectonicStressTensionalStressCompressionalStressShearStressFaultscanbedivideddependingonthedirectionofrelativedisplacementThereare2maincategoriesDipslipfaultswherethedisplacementisverticalStrikeslipfaultswherethedisplacementishorizontalRelativedisplacementislargelyafunctionofthetypeoftectonicstresstherockisunderDipSlipFaultsNormalFaultsNormalfaultsresultfromtensionalstressesalongdivergentboundariesThehangingwallblockmovesdownrelativetothefootwallblockEarthquakesgeneratedtendtohavelowRichtermagnitudesduetothetendencyofrockstobreakeasilyundertensionalstressTheearthquakestendtobeshallowfocuslessthan20kmbecausethelithosphereisrelativelythinalongdivergingplateboundariesExamplesallmidoceanridgesContinentalRiftValleyssuchasthebasinandrangeprovinceoftheWesternUSandtheEastAfricanRiftValleyDipSlipFaultsReverseFaultsReversefaultsresultfromcompressionalstressesalongconvergentboundariesThehangingwallblockhasmoveduprelativetothefootwallblockAThrustFaultisaspecialcaseofareversefaultwherethedipofthefaultislessthan15oTherearetwotypesofconvergingplateboundariesSubductionBoundariesAtsubductionboundariescoldoceaniclithosphereispusheddownintothemantleproducingacontinuumofstressalongthesubductingplateShallowfocusearthquakescanbegeneratednearthetrenchbutfocaldepthscanreachdownto700kmasearthquakesaregeneratedalongthesubductingplateRocksarestrongundercompressionandcanstorelargeamountsofstrainenergybeforetheyruptureThereforetheseearthquakescanbeverypowerful1960SouthernChili951964Alaska92CollisionBoundariesAtcollisionboundariestwoplatesofcontinentallithospherecollideresultinginfoldthrustmountainbeltsEarthquakesoccurduetothethrustfaultingandrangeindepthfromshallowtoabout200kmExampleTheHimalayasfromthecollisionofIndiawithAsia525d2ecf46bf0fb5cffcf14db20bc0Page 1 of 5
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