• Franke, Steven

Abstract

Seismic Tomography in Reykjanes, SW IcelandPhilippe Jousset1, Hanna Blanck2, Steven Franke1,3, Malte Metz1,4, Kristján Ágústsson2, Arie Verdel5, Trond Ryberg1, Gylfi Páll Hersir2, Cornelis Weemstra6, David Bruhn1, ÓlafurFlovenz21GFZ Potsdam, Telegrafenberg, 14473 Potsdam, Germany 2ISOR, Iceland GeoSurvey, Reykjavik, Iceland;3AWI, Neumayer Station, Antarctica 4 Potsdam University, Germany 5TNO,Utrecht,the Netherlands6Universityof Technology, Delft, the Netherlandspjousset@gfz.potsdam.deABSTRACT Wepresenttomographicresultsobtained around geothermalreservoirs usingseismicdatarecorded bothon-landReykjanes,SW-Icelandandoffshore alongReykjanesRidge.Wegatheredrecordsfroma networkof83seismicstations(including21Ocean BottomSeismometers)deployedbetweenApril2014 andAugust2015.Weobtaincrustalvelocityimages fromseveraltomographymethods.First,weused localearthquakestoperformtraveltimetomography. The processing includes first arrival picking of P-and S-phasesusinganautomaticdetectionandpicking techniquebasedonAkaikeInformationCriteria.We locateearthquakesbyusinganon-linearlocalization technique,as apriori informationforderivinga1D velocitymodel.Wethencomputed a 3Dvelocity model by joint inversion of each earthquake’s location andvelocitylateralanomalieswithrespecttothe1D model. Our results confirms previous models obtained inthearea,withenhanceddetails.Second,we used ambientnoisecross-correlationtechniques which involvethecomputationofcross-correlationbetween seismicrecords.Empirical Green’sfunctionsare estimatedand analyzedtoderiveanS-wavevelocity modelbysurfacewavetomography.Third,noise correlationtheoryshowsthatzero-offsetP-wave reflectivityatselectedstationlocationscanbe approximatedbyauto-correlatingandstackingstation data.Withfewassumptions,single-stationauto-correlationsprovidelocal1Dhigh-resolution structuralacoustic-contrastversusdepthinformation. Weshowthattheapplicationofambientnoise interferometryforreflectionretrieval complement well theresultsfrom bothclassicalandnoise tomography methods.

Topics

• tomography