SHEAR-WAVE VELOCITY STRUCTURE BENEATH EUROPE, THE NORTHEASTERN ATLANTIC AND WESTERN ASIA FROM WAVE-FORM INVERSIONS INCLUDING SURFACE-WAVE MODE-COUPLING

Waveforms of 449 seismograms have been inverted for S-wave velocity st ructures beneath Europe, the northeastern Atlantic, and western Asia d own to a depth of 670 km. Recorded waveforms were used in the time win dow starting at the S-wave arrival and ending after the fundamental-mo de Rayleigh-wave arrival. The inversion method is based on the partiti oned waveform inversion (Nolet 1990), with the difference that synthet ic seismograms are calculated taking surface-wave mode coupling into a ccount in order to model body waves in laterally heterogeneous media m ore accurately. The partitioning of the inversion procedure makes non- linear optimization feasible, even for inversions including surface-wa ve mode coupling. The non-linear inversion of the waveforms resulted i n linear constraints on the 3-D velocity structure. In a second step, these constraints were used in a linear inversion for the 3-D shear-wa ve velocity model beneath Europe, the northeastern Atlantic and wester n Asia. The EUR-SC'95 model is presented, which is characterized by a wide range of length-scales of the velocity structures. In central Eur ope, where the ray density is highest, small-scale structures are reco vered, such as the presence of high velocities associated with the Hel lenic subduction zone. On the edges of the inversion model, where the ray density (and therefore also the resolution) is poorer, we find lar ger-scale features, such as the relatively laterally homogeneous high- velocity structure beneath the Russian Platform to a depth of 300 km. In this paper we discuss the inversion method, data processing, parame trization difficulties due to the introduction of surface-wave mode co upling, spatial resolution of the model, and structures in the EUR-SC' 95 model.