IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS013 Poster presentation 2249
Surface wave tomography in Euro-Mediterranean region
Dr. Renata Schivardi
Andrea Morelli
We present a transversely isotropic shear wave velocity model of the upper mantle beneath Europe and
the Mediterranean region, obtained by non-linear inversion of surface wave group velocity maps. Group
velocity maps result from the regionalization of a dataset of measurements of fundamental mode Love
and Rayleigh wave dispersion, carried out with iterated multiple filtering, and phase-matched filtering
techniques. The linear inverse problem is stabilized using a priori information in the form of a global
group velocity reference model, derived from the inversion of the phase velocity dataset of Ekstrom et
al. (1997). The implications of different regularization constraints (mathematically equivalent to norm
damping or smoothing with different criteria) are analyzed and compared. Both in group velocity maps
and in shear velocity resulting model we find confirmation of the larger-scale deep geological features
known for the region, namely the differentiation between fast old cratonic shields of Eastern Europe and
North Western Africa and the slow seismic active Tethyan belt. At shorter scale length we image well
slow anomalies associated with the magmatic provinces of the Sicily Channel, and the extensional zone
of the Rhine graben. Fast anomalies are instead related to the Aegean and Hellenic Arc. Use of the
dense European seismograph array results in maps with higher resolution than previously attained.
Keywords: surface waves, tomography