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Propagation of surface waves from the Greek earthquakes across Europe

Propagation of surface waves from the Greek earthquakes across Europe. R. Ga z dova 1 ,2 , P. Kolinsky 1 , J. Malek 1 & PASSEQ working group 1 Academy of Sciences of the Czech Republic - Institute of Rock Structure and Mechanics 2 Charles University in Prague – Faculty of Science.

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Propagation of surface waves from the Greek earthquakes across Europe

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  1. Propagation of surface wavesfrom the Greek earthquakesacross Europe R. Gazdova1,2, P. Kolinsky1, J. Malek1 & PASSEQ working group 1 Academy of Sciences of the Czech Republic - Institute of Rock Structure and Mechanics 2 Charles University in Prague – Faculty of Science ESC2010, Montpellier, France, September 8, 2010

  2. map of used seismic stations and EQs data: ORFEUS PASSEQ Czech Regional network IRSM stations

  3. classical approach – one station GREECE EQ AT STATION KHC (Czech republic) epicentral distance:1393 km 08.06.2008, 12:25:29.89 GMT Mw = 6.4, Ms = 6.1 Rayleigh wave Love wave

  4. regional approach – many stations classicalregional approach one station many stations many periods one period (consecutively many p.) one dispersion curve no dispersion curve identification of several modes identification of one mode at one station at many stations advantage advantage easy identification of the dispersion easy identification of the modes (fundamental, higher, reflected)

  5. SVAL surface wave analysis • multiple filtering • Gaussian filters • constant relative resolutionfiltering • instantaneous period estimation spectrum frequency (Hz) time (s)

  6. five local envelope maxima of all quasiharmonic components obtained by the inverse Fourier transform are found and their propagation times determined • maxima represent different modes of direct surface waves as well aspossible reflected, converted and multipathed modes

  7. predominant directions of surfacewavefront propagation of different modes are estimated by sorting the found propagation times across Europe according to their temporal and spatial correlation with implications for location of the scattering heterogeneities and reflection structures in Central Europe time (s) time (s) for 1 period: 173 stations * 5 maxima = 865 arrival times at 1 filter we use approx. 100 filters for 1 station = 86500 arrival times time (s)

  8. 10 s

  9. 20 s

  10. 30 s

  11. 40 s

  12. 50 s

  13. 60 s

  14. 70 s

  15. 80 s

  16. Rayleigh waves, R component, 50 s

  17. 50 s Tornquist-Teisseyre zone

  18. preliminary results • method of regional surface wave mode identification was introduced • fundamental and first higher modes were identified • reflections of fundamental modes were found • propagating from the Aegean Sea, Rayleigh waves pronounce significant first higher mode (R and Z component) • as opposed to that, Love waves do not • reflection from Tornquist-Teisseyre zone were found at 50 s for Rayleigh waves (R component)

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