Earthquakes and Seismic WavesEarthquake 2009 November 4• Intensity of earthquake• Length of shaking (duration)• ‘Soil’ type—the nature of the material upon which the structure rests• Building design—how well it is designed and builtEarthquake destruction Mercalli Intensity ScaleMagnitude• Richter Magnitude– Size of waves recorded on the seismograph– Corrected for distance from quake• Moment Magnitudealso includes:– Size of surface rupture– Nature of material transmitting the seismic waves• Both in contrast to number on Mercalliintensity scale, that refers to what are the effects in a locationRichter magnitude determined by seismic wave recording on a seismogramDestruction from• Ground shaking• Landslides and subsidence• Liquefaction• Tsunami•FireIzmet, Turkey Charleston, SC Intensity of New Madrid, MO• 1811-1812•ML to 7.8• Altered course of Mississippi River• Toppled chimneys in Cincinnati and Richmond• http://hsv.com/genlintr/newmadrd/LA Basin Fault Map• Northridge Hills Fault is the pale purple crossing the pink y-shaped one making an X shape just north of US 101http://www.data.scec.org/chrono_index/northreq.htmlNorthridge 1994 January 17 Northridge 1994--freeway• http://www.geo.lsa.umich.edu/~crlb/COURSES/107/Lec7/lec7.htmlSan Fernando Valley, Jan 1994• http://www.data.scec.org/chrono_index/northreq.htmlCal State Northridge Parking Structure• http://www.data.scec.org/chrono_index/northreq.htmlNorthridge Parking structure• http://www.vibrationdata.com/earthquakes/northridge.htmKobe plate movement• http://www.georesources.co.uk/kobehigh.htmKobe, Japan, 1995• http://vathena.arc.nasa.gov/curric/land/kobe.htmlKobe, Japan, 1995• http://www.dis-inc.com/kobe.htmKobe damage due to construction techniques• http://www.georesources.co.uk/kobehigh.htmGood Friday quake, 1964 Department Store DamageTurnagain Heights 1964--landslideAnchorage, subsidence Loma Prieta 1989• http://jamaica.u.arizona.edu/ic/nats1011/lectures/ch09/FIG09_019A.JPGLoma Prieta—freeway collapse• http://www.dola.state.co.us/oem/PublicInformation/EARTHQUAKE.HTMLoma Prieta, 1989• http://pubs.usgs.gov/dds/dds-29/Sumatra, September 2009Sumatra, September 2009• http://www.time.com/time/world/article/0,8599,1927623,00.htmlSumatra 2009•http://www.monstersandcritics.com/news/asiapacific/features/article_1505000.php/In-Pictures-Indonesia-Earthquake-October-4th?page=9Sumatra 2009•http://www.life.com/image/90350637Loma Prietamud volcanoes• LiquefactionMexico Liquefaction 1985 Japan 1964--liquifaction• http://www.uwsp.edu/geo/faculty/ozsvath/images/liquefaction_photo.htmTsunami formation Samoa, 2009• http://www.time.com/time/photogallery/0,29307,1926846,00.html• http://www.time.com/time/photogallery/0,29307,1926846,00.htmlTsunami Indonesia 2004 Tsunami Indonesia 2004 Tsunami Indonesia 2004Tsunami Hawaii 1946 Tsunami Travel Times Northridge, 1994Probability of Magnitude Quakes• 2009 so far (Nov 3, 2009)• 33 @ 6.0 to 6.9• 14 @ 7.0-7.9 (many in Indonesia, South Pacific)• 1 @ 8.1 Samoa: September 29Probability of Calif. Quakes in 30 year periodSeismic waves tell us about Earth’s interior• Speed changes with composition, properties, pressure• Refract at boundaries within Earth• Some penetrate all types of material, some only penetrate solids• Our “MRI” of EarthLithosphere, Mantle relation“Lower mantle” _____Don’t use the other termPrimary Wave diffraction P and S wave shadowsEarth’s interior compositionDefined by chemical compositionCrustMantleCoreEarth’s interior propertiesDefined by PhysicalPropertiesLithosphereAsthenosphereLower mantleOuter coreInner coreInner Core boundaryLehmann discontinuityOcean with central ridge Ocean-Continent Convergence Tectonic Plate Map•
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