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Brief Overview of Threat Posed by the New Madrid Seismic Zone

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Brief Overview of Threat Posed by the New Madrid Seismic Zone BRIEFBRIEF OVERVIEWOVERVIEW OFOF SEISMICSEISMIC THREATTHREAT POSEDPOSED BYBY THETHE NEWNEW MADRIDMADRID SEISMICSEISMIC ZONEZONE J.J. DavidDavid Rogers,Rogers, Ph.D.,Ph.D., P.E.,P.E., R.G.,R.G., C.E.G.C.E.G. Karl F. Hasselmann Chair in Geological Engineering Natural Hazards Mitigation Institute University of Missouri-Rolla EARTHQUAKESEARTHQUAKES 44 millionmillion earthquakesearthquakes occuroccur everyevery year;year; oror aboutabout 11,00011,000 eacheach dayday AboutAbout 6,2006,200 quakesquakes areare strongstrong enoughenough forfor peoplepeople toto noticenotice AboutAbout 800800 damagingdamaging quakesquakes betweenbetween MagnitudeMagnitude 5.05.0 andand 5.95.9 eacheach yearyear AboutAbout 120120 destructivedestructive quakesquakes withwith MagnitudesMagnitudes 6.06.0 toto 6.96.9 eacheach yearyear DespiteDespite improvedimproved buildingbuilding codes,codes, aboutabout 15,00015,000 peoplepeople areare killedkilled eacheach yearyear QUAKESQUAKES KILLKILL PEOPLEPEOPLE InIn 1556,1556, 830,000830,000 peoplepeople werewere killedkilled inin ShensiShensi,, ChinaChina 180,000180,000 killedkilled nearnear KansouKansou,, ChinaChina inin 19201920 quakequake 9,5009,500 peoplepeople werewere killedkilled andand 30,00030,000 injuredinjured inin MexicoMexico CityCity inin SeptemberSeptember 19851985 byby aa M8.1M8.1 earthquakeearthquake 350350 kmkm away!away! InIn 2003,2003, 43,81943,819 peoplepeople werewere killedkilled byby earthquakesearthquakes worldwideworldwide GeologyGeology beneathbeneath sitesite isis justjust asas importantimportant asas quakequake magnitudemagnitude EarthquakeEarthquake MagnitudeMagnitude versusversus EnergyEnergy ReleaseRelease Modern earthquake magnitudes are based on energy release using a logarithmic scale Each numerical magnitude is about 33X the energy release of preceding numerical value In 1663 the European settlers experienced their first earthquake in America. From 1975-1995 there were only four states that did not have any earthquakes: Florida, Iowa, North Dakota, and Wisconsin. The most damaging earthquakes have occurred in California, Nevada and Alaska. Should we be concerned in the Midwest? Isoseismal lines for the December 16, 1811 Ms 8.6 New Madrid earthquake Felt over an area greater than 1 million square miles Extensive damage to masonry in Cincinnati Rang church bells in Boston Most people lived along rivers in Midwest and no inhabitants west of the Mississippi NEWNEW MADRIDMADRID STRESSSTRESS FIELDFIELD SolutionSolution forfor distributiondistribution ofof thethe elasticelastic stressstress fieldfield inin thethe crustalcrustal basementbasement atat aa depthdepth ofof 1212 kmkm forfor earthquakesearthquakes feltfelt inin latelate 18111811 andand earlyearly 18121812 NEWNEW MADRIDMADRID SEISMICSEISMIC ZONEZONE 20002000 quakesquakes inin NewNew MadridMadrid SeismicSeismic ZoneZone inin 18111811--12;12; fourfour withwith M>M> 7.57.5 FeltFelt overover 11 millionmillion squaresquare miles!miles! ChimneysChimneys toppledtoppled inin Cincinnati,Cincinnati, Ohio,Ohio, 560560 kmkm awayaway RaisedRaised andand loweredlowered vastvast tractstracts ofof landland asas muchmuch asas 2020 feet,feet, temporarilytemporarily reversingreversing flowflow ofof MississippiMississippi RiverRiver GroundGround fissuresfissures andand massivemassive liquefactionliquefaction overover aa zonezone measuringmeasuring 240240 xx 8080 km!km! POSTPOST 18121812 SEISMICITYSEISMICITY inin NEWNEW MADRIDMADRID SEISMICSEISMIC ZONEZONE M6.3M6.3 quakequake inin MarkedMarked Tree,Tree, ARAR inin 1843;1843; diddid considerableconsiderable damagedamage toto Memphis,Memphis, 6060--7070 kmkm easteast M6.6M6.6 quakequake inin Charleston,Charleston, MOMO inin 1895;1895; FeltFelt inin 2323 states,states, 3030 kmkm ofof sandsand blowsblows M5.4M5.4 inin WabashWabash ValleyValley (Dale,(Dale, IL)IL) inin 1968;1968; alsoalso feltfelt inin 2323 states;states; lightlight damagedamage inin St.St. LouisLouis M5.0M5.0 inin WabashWabash ValleyValley westwest ofof Vincennes,Vincennes, ININ (Olney,(Olney, IL)IL) inin 19871987 M4.6M4.6 nearnear Evansville,Evansville, ININ inin 20022002 AACTIVECTIVE SEISMICITYSEISMICITY EpicentersEpicenters recordedrecorded betweenbetween 19741974--9696 describedescribe aa seismicallyseismically activeactive zonezone ofof complexcomplex intraplateintraplate tectonicstectonics RightRight laterallateral strikestrike slipslip andand blindblind thrustthrust faultingfaulting occuroccur inin thethe samesame regionregion OTHEROTHER SEISMICSEISMIC SOURCESSOURCES NotNot allall ofof thethe region’sregion’s quakesquakes emanateemanate fromfrom thethe recognizedrecognized NewNew MadridMadrid ZoneZone OtherOther sourcessources likelylikely DAMAGEDAMAGE POTENTIALPOTENTIAL Published damage predictions for the New Madrid Seismic Zone have focused on the near field area, in the upper Mississippi Valley These are based on synthetic motion time histories with assumed soil cover; not on site specific characteristics or dynamic properties of structures. EARTHQUAKEEARTHQUAKE MECHANISMSMECHANISMS THATTHAT COMMONLYCOMMONLY IMPACTIMPACT STRUCTURESSTRUCTURES SurfaceSurface faultfault rupturerupture hazardshazards GroundGround waveswaves andand flingfling effectseffects TopographicTopographic enhancementenhancement ofof seismicseismic energyenergy DynamicDynamic consolidationconsolidation ofof soilssoils LiquefactionLiquefaction andand laterallateral spreadingspreading SiteSite amplificationamplification effectseffects LongLong periodperiod motionmotion andand resonantresonant frequencyfrequency effectseffects OutOut--ofof--phasephase structuralstructural responseresponse SURFACESURFACE FAULTFAULT RUPTURERUPTURE HAZARDSHAZARDS Anastomosing fault splays Major active faults usually exteendnd up to the groundground surface, where they can pose a threat to structures. Only about 2% of earthquake-induced structural damage is caused by surface fault rupture. Various fault strands identified near the ground surface may be active, dormant or ancient, as shown above. SURFACESURFACE RUPTURERUPTURE OnlyOnly aa smallsmall percentagepercentage ofof earthquakesearthquakes actuallyactually causecause noticeablenoticeable surfacesurface faultfault rupturerupture SometimesSometimes itit isis ratherrather discretediscrete (upper(upper left)left) OnOn otherother occasionsoccasions itit cancan bebe veryvery abruptabrupt andand graphicgraphic (lower(lower left)left) FREEFREE BOUNDARY/BOUNDARY/ GROUNDGROUND WAVEWAVE EFFECTEFFECT As the seismic wave train propagates upward and along the Earth’s surface, the peak ground accelerations will tend to increase at the ground surface because there is no confinement. Tunnels and underground openings usually record much lower values of acceleration due to their increased confinement. TOPOGRAPHICTOPOGRAPHIC INFLUENCEINFLUENCE ONON SITESITE RESPONSERESPONSE Steep-sided bedrock ridges usually experience much higher accelerations during earthquakes because they are less laterally constrained. In the October 1989 Loma Prieta earthquakearthquakee the PGA of 0.77g was recordedrecorded in thethe valley bottombottom at Corralitos. Estimates of PGA values for the adjoining ridges were in excess of 1.30g. Fill embankments tend to consolidate and settle under dynamic loading in the near-field zone Regardless of the compactive effort engendered to filled ground during placement, these materials tend to compress during earthquake- induced shaking, often causing abrupt settlement of the approach fills at the abutments. MechanismMechanism ofof seismicallyseismically--inducedinduced settlementsettlement ofof bridgebridge approachapproach fillfill prismsprisms QUAKEQUAKE--INDUCEDINDUCED SETTLEMENTSETTLEMENT ApproachApproach fillsfills forfor pilepile supportedsupported bridgesbridges commonlycommonly exhibitexhibit grievousgrievous differentialdifferential settlementsettlement ImpactsImpacts traffictraffic flowflow andand anyany entrainedentrained utilities,utilities, likelike firefire mainsmains TheseThese examplesexamples areare fromfrom AugAug 19991999 ChiChi ChiChi earthquakeearthquake inin TaiwanTaiwan APPROACHAPPROACH FILLFILL SETTLEMENTSETTLEMENT SeismicallySeismically--inducedinduced settlementsettlement andand lurchinglurching ofof approachapproach fillsfills forfor thethe CayumapaCayumapa RiverRiver BridgeBridge nearnear ValdiviaValdivia,, Chile,Chile, whichwhich occurredoccurred duringduring thethe M9.5M9.5 MayMay 19601960 earthquakeearthquake ReplacementReplacement structurestructure beingbeing constructedconstructed inin lowerlower view,view, usingusing GeofoamGeofoam TschebotarioffTschebotarioff (1973)(1973) presentedpresented casecase studiesstudies ofof pilepile supportedsupported bridgesbridges thatthat failedfailed becausebecause ofof approachapproach fillfill settlementsettlement.. SETTLEMENTSETTLEMENT OFOF APPROACHAPPROACH FILLFILL Crib wall supported approach fill for pile supported bridge. As fill consolidated, crib wall deformed and supporting piles deflected inward, towards channel. Taken from Tschetarioff (1973). LIQUEFACTIONLIQUEFACTION BridgeBridge failuresfailures duringduring AprilApril 19911991 M7.5M7.5 CostaCosta RicaRica earthquakeearthquake ThoughThough supportedsupported onon steelsteel andand concreteconcrete pilespiles respectively,respectively, thesethese bridgesbridges bothboth failedfailed duedue toto liquefactionliquefaction ofof foundationfoundation materials,materials, whichwhich tiltedtilted thethe pilespiles LIQUEFACTIONLIQUEFACTION
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