Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/1562
AuthorsMargheriti, L.* 
Nostro, C.* 
Amato, A.* 
Cocco, M.* 
TitleSeismic anisotropy: an original tool to understand the geodynamic evolution of the Italian peninsula
Issue DateJun-1997
Series/Report no.40/3
URIhttp://hdl.handle.net/2122/1562
Keywordsseismic anisotropy
geodynamics
crust
upper mantle
Subject Classification04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics 
AbstractAnisotropy is a common property of the Earth's crust and the upper mantle; it is related to the strain field of the medium and therefore to geodynamics. In this paper we describe the different possible origins of anisotropic behavior of the seismic waves and the seismological techniques used to define anisotropic bodies. In general it is found that the fast polarization direction is parallel to the absolute plate motion in cratonic areas, to the spreading direction near rifts or extensional zones, and to the main structural features in transpressive regimes. The delay times between fast and slow waves reflect the relative strength and penetration at depth of the deformation field. The correspondence between surface structural trends and anisotropy in the upper mantle, found in many regions of the world, strongly suggest that orogenic processes involve not only the shallow crust but the entire lithosphere. Recently in Italy both shear wave splitting analysis and Pn inversion were applied to define the trend of seismic anisotropy. Along the Northern Appeninic arc fast directions follow the strike of the arc (i.e., parallel to the strike of the Miocene-Pleistocene compressional features), whereas in the Tyrrhenian zone fast directions are about E-W SW-NE; parallel to the post-Miocene extension that is thought to have reoriented the mantle minerals fabric in the astenosphere.
Appears in Collections:Manuscripts
Annals of Geophysics

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