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 Mechanics2 Charles University in Prague Faculty of ScienceESC 2010, Montpellier, France, September 8, 2010

map of used seismic stations and EQsdata: ORFEUS PASSEQCzech Regional networkIRSM stations

Eartquakedatecentroid timelatitudelongitudedepth [km]MwMs20070325135825.3.200713:57:58.20038.3420.42155.75.820070410031710.4.200703:17:56.35038.5521.6425.05.420070629180929.6.200718:09:11.22039.2720.26105.45.420080214100914.2.200810:09:22.72036.521.67296.96.720080214120914.2.200812:08:55.79036.3521.86286.56.020080220182720.2.200818:27:06.00036.2921.7796.26.22008060812258.6.200812:25:29.71037.9621.52166.46.3

classical approach one stationGREECE EQ AT STATION KHC (Czech republic)epicentral distance: 1393 km08.06.2008, 12:25:29.89 GMT Mw = 6.4, Ms = 6.1 Rayleigh waveLove wave

regional approach many stationsclassicalregional approach

one stationmany stationsmany periodsone period (consecutively many p.)one dispersion curveno dispersion curve

identification of several modesidentification of one mode at one stationat many stations

advantageadvantageeasy identification of the dispersioneasy identification of the modes(fundamental, higher, reflected)

multiple filteringGaussian filtersconstant relative resolution filteringinstantaneous period estimationSVALsurface wave analysisspectrumfrequency (Hz)time (s)

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

predominant directions of surface wavefront 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 Europetime (s)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

10 s

20 s

30 s

40 s

50 s

60 s

70 s

80 s

Rayleigh waves, R component, 50 s

50 sTornquist-Teisseyre zone

preliminary resultsmethod of regional surface wave mode identification was introducedfundamental and first higher modes were identifiedreflections 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 notreflection from Tornquist-Teisseyre zone were found at 50 s for Rayleigh waves (R component)

200 broadband station