HR: 1340h
AN: T53B-0499    [Abstracts]
TI: Toroidal mantle flow around the calabrian slab (italy) from shear-wave splitting
AU: * Margheriti, L
EM: margheriti@ingv.it
AF: Istituto Nazionale di Geofisica e Vucanologia, Via di vigna Murata 605, Roma, 00143 Italy
AU: Civello, S
EM: civello@ingv.it
AF: Istituto Nazionale di Geofisica e Vucanologia now at ENI, San Donato, Milano, 20100 Italy
AB: Shear-wave birefringence is likely caused by ongoing and/or fossil mantle flow. Splitting parameters in the Southern Tyrrhenian subduction zone define a quite complex pattern of fast directions with large delay times up to 2.7s. Fast directions are prevalently trench parallel below the slab and rotate to trench normal at the western edge of the slab depicting a ring around it. We locate the different contribution of sub and supraslab anisotropy using SKS phases and local S from deep earthquakes. We interpret these anisotropic pattern as toroidal mantle flow induced by rollback subduction as observed in laboratory experiment.
DE: 9335 Europe
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8150 Plate boundary--general (3040)
DE: 7203 Body wave propagation
DE: 7218 Lithosphere and upper mantle
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting