nisar: the nasa-isro sar mission landslide hazards to … · 2017-03-23 · indian space research...

ã2017CaliforniaInstituteofTechnology.Governmentsponsorshipacknowledged.

NISAR:TheNASA-ISROSARMission

MonitoringGroundMovementAssociatedwithLandslidesLandslides occur in soil or rock when the gravitationalforceonahillslopeexceedsthestrengthoftherockorsoil.Mostoftenthisoccursinareaswithsteepslopes,during

orfollowingheavyrainfallorsnowmelt,andfromshakingduetoearthquakes.

LandslideHazardstoInfrastructure

Landslides and other geologic hazards kill dozens of people and causeseveralbilliondollarsofdamageeveryyearintheUnitedStates.Landslidescanalsocausesignificantenvironmentaldamageandsocietaldisruption.

Landslides Can Move Slowly or Fail Catastrophically

Landslides and related slope movements can begin and move in a widevarietyofways,dependingonthegeology,soilandground-waterconditions,vegetationcover,andweather.Somelandslidesmoveatratesofafractionofaninchperyearandcanremainactiveforperiodsofdecadesorlonger,slowlycausingdamagetobuildings,highwaysandotherstructures.Othersfailcatastrophicallyandtravelatratesoftensofmilesperhour,causinglossofinfrastructureandlife.Landslidesizesalsovarygreatly,fromsmallshallowslumpsandslidesthatareonlyacoupleyardsacrosstolargedeep-seatedslides and flows that can reach lengths of severalmiles.Many landslidesmovemultipletimes,soreactivationisoftenaconcern.Right:TheLaConchitalandslidethatburiedmanyhousesin2005,whenapre-existing landslidewasreactivatedandrapidlymoveddownslope (fromUSGSOpenFileReport2005-1067).

TheNISARMission–Reliable,ConsistentObservations

TheNASA–ISROSyntheticApertureRadar (NISAR)mission,a collaborationbetweentheNationalAeronauticsandSpaceAdministration(NASA)andtheIndian Space Research Organization (ISRO), will provide all-weather,day/night imaging of nearly the entire land and ice masses of the Earthrepeated 4-6 times per month. NISAR’s orbiting radars will image atresolutions of 5-10meters to identify and track subtle movement of theEarth’s land and its sea ice, and even provide information about what ishappeningbelowthesurface.Itsrepeatedsetofhighresolutionimagescaninform resourcemanagement and be used to detect small-scale changesbeforetheyarevisibletotheeye.Productsareexpectedtobeavailable1-2daysafterobservation,andwithinhoursinresponsetodisasters,providingactionable,timelydataformanyapplications..

ã2017CaliforniaInstituteofTechnology.Governmentsponsorshipacknowledged.

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LandslidesinthelastfewyearshavecausedwidespreadfatalitiesandmajordamageintheUnitedStates.Duringatwo-yearperiodbetween2014and2016,61peoplewerekilled, including 43 in the Oso landslide in WashingtonState (Coe, 2016). Globally, between 2000 and 3000peoplearekilledbylandslideseveryyear(Petley,2017).NISARwillbeabletomeasuregroundsurfacemovementdirectlythroughrepeatimagingoflandslideproneregionsand processing the sequence of images using syntheticaperture radar interferometry (InSAR), which canmeasure changes in the distance between the radarantennaand thegroundat the scaleofa fractionofaninch.OnemajoradvantageofInSARisthatitcanbeusedto measure surface deformation directly across largeareas(hundredsofmiles)withfargreateraccuracythanis

possible with other commonly used remote sensing orground-based monitoring techniques (e.g., GPSsurveying).Radarhasadditionaladvantagesoverground-basedandopticalmethods,themostsignificantofwhichistheabilitytoseethroughclouds,smoke,andhaze,andtheabilitytoimagethegroundsurfaceduringdayornightwithoutrelyingonsolarillumination.AllNISARdataproducts, includingtheproductsshowingsurfacemovement,willbefreelyavailablethroughawebportal.Thisway,thenation’sinvestmentinlandsurveysremotely acquired from space can bewidely used by avariety of agencies and individuals to detect landslidemovement when it begins to happen, and potentiallypreventfurtherlandslidemovementfromcausinghumanandeconomicdisasters.

NationalAeronauticsandSpaceAdministrationFormoreinformation,visithttp://nisar.jpl.nasa.gov/applications

JetPropulsionLaboratory/CaliforniaInstituteofTechnology/Pasadena,California/www.jpl.nasa.gov

MapshowingareasoftheconterminousUnitedStateswithnegligible(gray)andsome(red)susceptibilitytolandslides[ModifiedfromGodtetal.,2012]

Somelandslidesmoveslowlyoveralongtime,graduallydamagingroads,pipes,andotherinfrastructure.Oneexampleisshownattheright,wheregroundmovementoflandslidesintheBerkeleyHillsofCaliforniabetween2008and2010wascapturedusingUAVSAR,NASA’sairborneprototypefortheNISARspacemission.Inthistypeofmap,calledaninterferogram,thecolorsshowcontoursofgroundmovement.AregularscheduleofradarimagingwithNISAR,whichwillimageallthelandintheUnitedStatesandnearlyalllandglobally,willenabledetectionofslow-movinglandslides,sodamagecanbeavoided,andpotentiallyprovideforewarningofrapidlandslidesintheweekstomonthspriortotheircatastrophicfailure.Asaresult,theserelativelycommonandhighlydestructivegeologichazardswillbeidentifiedmorequickly,efficiently,andeconomically,helpingscientists,engineers,andpolicymakersprotectlivesandproperty.

Monitoring Landslide Motion with Radar