Tomography and velocity structure of the crust and uppermost mantle in southeastern Europe obtained from surface wave analysis |
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| Authors: | R Raykova S Nikolova |
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| Institution: | (1) Geophysical Institute of BAS, Acad. G. Bonchev str., bl. 3, 1113 Sofia, Bulgaria;(2) Istituto Nazionale di Geofisica e Vulcanologia, sede di Bologna, via D. Creti 12, 40128 Bologna, Italy |
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| Abstract: | A set of two hundred shear-wave velocity models of the crust and uppermost mantle in southeast Europe is determined by application
of a sequence of methods for surface-waves analysis. Group velocities for about 350 paths have been obtained after analysis
of more than 600 broadband waveform records. Two-dimensional surface-wave tomography is applied to the group-velocity measurements
at selected periods and after regionalisation, two sets of local dispersion curves (for Rayleigh and Love waves) are constructed
in the period range 8–40 s. The shear-wave velocity models are derived by applying non-linear iterative inversion of local
dispersion curves for grid cells predetermined by the resolving power of data. The period range of observations limits the
velocity models to depths of 70 km in accordance to the penetration of the surface waves with a maximum period of 40 s. Maps
of the Moho boundary depth, velocity distribution above and below Moho boundary, as well as velocity distribution at different
depths are constructed. Well-known geomorphologic units (e.g. the Pannonian basin, southeastern Carpathians, Dinarides, Hellenides,
Rodophean massif, Aegean Sea, western Turkey) are delineated in the obtained models. Specific patterns in the velocity models
characterise the southeast Carpathians and adjacent areas, coast of Albania, Adriatic coast of southern Italy and the southern
coast of the Black Sea. The models obtained in this study for the western Black Sea basin shows the presence of layers with
shear-wave velocities of 3.5 km/s–3.7 km/s in the crust and thus do not support the hypothesis of existence of oceanic structure
in this region. |
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| Keywords: | surface waves group velocity tomography inversion shear-wave velocity structure southeastern Europe |
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