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1、★1Detectionofarbitrarilylargedynamicgroundmotionswithadensehigh‐rateGPSnetworkWedescribethedetectionofteleseismicsurfacewavesfromthe3November2002Mw7.9DenalifaultearthquakeinAlaskawithadensenetworkof1HzGPSstationsinsouthernCalifornia,about3900kmfromtheevent.Relativehorizonta
2、ldisplacementswithamplitudesinexcessof15mmanddurationof700secondsagreewithintegratedvelocitiesrecordedbynearbybroadbandseismometerswithanrmsdifferenceof2–3mm.Thedisplacementsarederivedfromindependent1HzinstantaneouspositionsdemonstratingthataGPSnetworkcanprovidedirectmeasur
3、ementsofarbitrarilylargedynamicandstaticgroundhorizontaldisplacementsatperiodslongerthan1sandamplitudesabove2mm,withaninherentprecision(signaltonoise)thatimprovesindefinitelywithamplitudewithoutclippingandinrealtime.High‐rate,real‐timeGPSnetworkscanenhanceearthquakedetectio
4、nandseismicriskmitigationandsupportotherapplicationssuchasintelligenttransportationandcivilinfrastructuremonitoring.Citation:Bock,Y.,L.Prawirodirdjo,andT.I.Melbourne(2004),Detectionofarbitrarilylargedynamicgroundmotionswithadensehigh‐rateGPSnetwork,Geophys.Res.Lett.,31,L066
5、04,doi:10.1029/2003GL019150.2Modifiedsiderealfiltering:Implicationsforhigh‐rateGPSpositioningHigh‐rate(1‐Hz)GlobalPositioningSystem(GPS)dataarebeginningtobeusedforavarietyofgeophysicalmonitoringpurposes,includingseismology.Improvingtheprecisionofhigh‐rateGPSpositionestimate
6、swillincreasethevalueofthese1‐HzGPSmonitoringsystems.Onetechniquethathasbeenusedtoimprovehigh‐rateGPSpositioningtakesadvantageofthegroundtrackrepeatperiodofthesatellites.ThisstudyinvestigatestheGPSorbitalrepeatperiodanddeterminesthatitvariesforeachsatelliteanddifferssignifi
7、cantlyfromthegenerallyassumedsiderealperiod.Orbitrepeatperiodsarecalculatedandusedtofilter1‐HzGPSpositionestimates.Usingthecalculatedorbitrepeatperiodsignificantlyreduceslowfrequency(0.001–0.04Hz)errorsin1‐HzGPSpositionestimates.Citation:Choi,K.,A.Bilich,K.M.Larson,andP.Axe
8、lrad(2004),Modifiedsiderealfiltering:Implicationsforhigh‐rateGPSpositioning,Geophy