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THE PRESENT DAY STRESS STATES IN THE MARMARA REGION. Yasemin KORKUSUZ and Nurcan Meral ÖZEL (yaseminkorkusuz@yahoo.com) Boğaziçi University Kandilli Observatory and Earthquake Research Institute Department of Geophysics İstanbul, TURKEY Baku - May, 2013.
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THE PRESENT DAY STRESS STATES IN THE MARMARA REGION Yasemin KORKUSUZand Nurcan Meral ÖZEL (yaseminkorkusuz@yahoo.com) Boğaziçi University Kandilli ObservatoryandEarthquake Research Institute Department of Geophysics İstanbul, TURKEY Baku - May, 2013
TheAnatolianBlockandThe Marmara Region (Reilingeret al., 2010)
Recent EarthquakeActivity of the Marmara Region ÇınarcıkBasin C. Eastern Tekirdağ Basin C. Yalova C. Eastern Ganos Offshore C. 5 Earthquake clusters Analyzed-600 eqs Selected-398 eqs Gemlik C.
Station Distribution Total 105 seismicstations
TheMethodology Selection of visibleearthquakeclusters Discrimination of earthquakes in terms of localmagnitudesusingshell in linux Earthquakes ML≥2.0 Earthquakes ML<2.0 Data merge - readingpolarities, and P and S pahasesby PQL-II Throwout Number of polarityper earthquake≥10 Number of polarityperearthquake<10 Throwout Convertingphasereading file intoNordic format Relocations by Hypocenter Application of themethod of Horiuchi et al. (1995) Source Mechanismsfor 1˚ gridsearchthroughthe program of Focmec SouceMechanismsfor 5˚ gridsearch Orientations of threeprincipalstressaxes Discrimination of faultplanesfromauxiliaryplanes
RESULTS 1. Eastern Ganos Offshore Cluster
Stress Tensor Inversion Results of the Eastern Ganoss Offshore Cluster
Stress Tensor Inversion Results of the Eastern Tekirdağ Basin Cluster
25.07.2011 ML5.2 and 7.06.2012 ML5.1 Marmara Sea earthquakes and Tekirdağ Basin Cluster
16.08.2011 (ML4.0)and 24.10.2006 (ML 5.2) Gemlik Gulf Earthquakes
CONCLUSION In thisstudy : • 600 eqhavebeenanalysedusing 105 seismicstationsrecords • Time period between 02.09.2006 and 31.03.2011 • Criteria: Minimum 10 polarityandmaximum 1 misfit • Number of earthquakesdecreasedfrom 600 to 398 • 9226 polarity and more than 15.000 P and S phases re-identfied for 398 eq • 398 ML≥2.0 earthquakeswere relocated • Individual focal mechanism solutions and stress tensor orientations have been obtained • 25 July 2011 ML5.2 and 7 June 2012 ML5.1 Tekirdağ Basin, and 16 August 2011 ML4.0 Gemlik Gulf earthquakes have been analysed Average Error Values • polarity: 23 • ERDP : 2.75 km • ERLN : 1.28 km • ERLT : 1.0 km • GAP : 63˚
Kandilli, İstanbul Thank You …