HR: 1340h
AN: T23A-1209    [Abstracts]
TI: Upper mantle structure of the European and Mediterranean region from inversion of surface wave group velocity
AU: * Schivardi, R
EM: renatas@bo.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Via D.Creti, 12, BOLOGNA, BO 40128, Italy
AU: Morelli, A
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Via D.Creti, 12, BOLOGNA, BO 40128, Italy
AB: We present a new transversely isotropic shear wave velocity model of the upper mantle in the European and Mediterranean region, obtained by analysis of surface wave group speed. Our data set consists of fundamental mode Love and Rayleigh wave group speed measurements, taken by multi-filter analysis on wave groups isolated by phase matched filtering on seismograms recorded at regional distance. Group velocity maps for periods ranging from 35 to 150s are then obtained by linear inversion. Data coverage in this region is not uniform, as it is highly influenced by the uneven distribution of stations and events. We therefore stabilize the inversion using a priori information in the form of a smooth global reference model we previously derived by inverting a phase velocity dataset (Ekstrom et al. 1997) on a global grid, where our regional grid is embedded. This greatly improves the coverage near the borders of our region. In each pixel - approximately 120 km in size - the set of group velocities are then used to find the best-fitting vertical shear velocity profile by nonlinear inversion. In this step, we make use of a priori knowledge from PREM and CRUST2.0. We present results in terms of Voigt average velocity variations, and radial anisotropy, and compare them with other results from the literature. The resulting model confirms the larger-scale deep geological features known for the region, and add great detail due to the inclusion of measurements on shorter paths.
DE: 8180 Tomography (6982, 7270)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting