Evidence of Plate Tectonics Earthquakes• Time To See Your AdvisorPlate MapAnimation link• http://www-personal.umich.edu/~vdpluijm/plates.gifhttp://www.ucmp.berkeley.edu/geology/tectonics.htmlDynamo that creates magnetic field• http://www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.htmlMovement of Magnetic North• http://www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.htmlMovement of Magnetic pole since 1600s• http://www.geolab.nrcan.gc.ca/geomag/long_mvt_nmp2_e.shtmlApparent Polar wandering for North America and EurasiaPole location with moving continentsMagnetic Reversals in volcanic stratigraphyMagnetic Reversal Age ScaleLava Magnetized in Normal FieldLava Magnetized in reversed fieldLater Lava Magnetized in Normal FieldSea floor spreading documented by magnetic reversalsMagne-tometerSurveyMagnetic AnomaliesAge of Sea Floor• http://earth.geol.ksu.edu/sgao/g100/plots/0829_04_age_of_ocean_floor.jpgEarthquake LocationsJapan Trench earthquakesJOIDES ResolutionAge of Emperor Seamount ChainVelocities of PlatesRadio TelescopePlate movement over 200 myWegener’s Pangaea200 mya (early Jurassic)150 mya (late Jurassic)100 million years ago90 mya (Cretaceous)50 mya (early Cenozoic)20 mya (late Cenozoic)Present DayIn 50 million years?In 250 million years??Lithospheric PlatesEarthquake Locations• http://earth.geol.ksu.edu/sgao/g100/plots/0916_global_seismicity.jpgPressure Wave• Push-pull motion• Parallel to direction of wave energy movement (propagation)• Go through all types of materials– Sound waves are pressure waves– Primary seismic waves are pressure wavesPrimary Wavehttp://astro.uchicago.edu/cara/outreach/se/ysi/1999/intro2.htmlShear Wave• Transverse--Side to side motion• Can only go through solid materials• Secondary seismic waves• Slower than primary wavesSecondary Wavehttp://astro.uchicago.edu/cara/outreach/se/ysi/1999/intro2.htmlEarthquake: seismic wavesWorld Series Earthquake apartment buildingSeattle, WA• Feb 28, 2001, Nisqually quake rocked the Central Puget Sound region • 6.2 Richter Magnitude • 6.8 Moment magnitude• Centered 57.5 km south-southwest of Seattle and 52.4 km deephttp://128.205.131.100:591/archives/Seattle.htmlhttp://www.scec.org/earthquakes/1906 San Francisco fireFocus, epicenter, faultOrange grove offset, So CalBefore deformationStrainRelease of strainAfter strain releasedSummary of elastic reboundSan Andreas Fault SystemSeismographSeismogram showing seismic wavesP-wavesP-wavesS-wavesS-wavesS-type surface wavesOcean-type surface wavesSummary of seismic wavesSeismic wave travel time curvesDifference of P and S wave travel timeMercalli scaleRichter magnitude determined by seismic wave recording on a seismogramEarthquake magnitudes and expected worldwide
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