Intermediate-period Rayleigh and Love waves propagating across Tibet indicate marked radial anisotropy within the middle-to-lower crust, consistent with a thinning of the middle crust by about 30%. The anisotropy is largest in the western part of the plateau, where moment tensors of earthquakes indicate active crustal thinning. The preferred orientation of mica crystals resulting from the crust...

The errors in plate motion azimuths inferred from shear wave splitting beneath any one tectonic plate are shown to be correlated with the errors of other azimuths from the same plate. To account for these correlations, we adopt a two-tier analysis: First, find the pole of rotation and confidence limits for each plate individually. Second, solve for the best fit to these poles while constraining...

The northeastern boundary of the Tibetan high plateau is marked by a 2 km topographic drop and a coincident rapid change in crustal thickness. Surface tectonics are dominated by the Kunlun strike-slip fault system and adjacent Kunlun concealed thrust. The main objective of the current study is to map lateral variations of seismic anisotropy parameters in this region along the linear INDEPTH IV ...

The orientation of crustal seismic anisotropy changed at least twice by up to 80 degrees because of volcanic eruptions at Ruapehu Volcano, New Zealand. These changes provide the basis for a new monitoring technique and possibly for future midterm eruption forecasting at volcanoes. The fast anisotropic direction was measured during three seismometer deployments in 1994, 1998, and 2002, providing...

We analyze seismic anisotropy for the Eastern Alpine region by inspecting shear-wave splitting from SKS and SKKS phases. The Eastern Alpine region is characterized by a breakdown of the clear mountain-chain-parallel fast orientation pattern that has been previously documented for the Western Alps and for the western part of the Eastern Alps. The main interest of this paper is a more detailed an...

S U M M A R Y Upper-mantle seismic anisotropy has been observed using a variety of methods, including S and SKS splitting, P and Pn traveltimes, P polarization anomalies and P to S conversions, and surface waves. Care must be taken when comparing the results from different methods because of bias introduced by depth sensitivity, frequency dependence, and simplifying assumptions concerning the f...

A general inversion scheme based on a genetic algorithm is developed to invert seismic observations for anisotropic parameters. The technique is applied to the inversion of shear-wave observations from two azimuthal VW data sets from the Conoco test site in Oklahoma. Horizontal polarizations and time-delays are inverted for hexagonal and orthorhombic symmetries. The model solutions are consiste...

Two end-member geometries, radial flow and ridge-channeled flow, have been proposed for the dispersion of material upwelling beneath Iceland. Seismic anisotropy provides information on mantle flow, and therefore has the potential to discriminate these two geometries. In this study, we combine the HOTSPOT and SIL datasets (39 stations) and select 28 events for teleseismic shear-wave splitting an...

Article history: Received 13 March 2014 Received in revised form 4 June 2014 Accepted 8 June 2014 Available online xxxx Editor: Y. Ricard

Des variations de paramètres physiques, avant et suite au séisme de Parkfield, 2004, Mw 6.0, et pouvant être associés à l’anisotropie sismique, ont été extraites des ondes de surface reconstruites par la méthode de cross-corrélation du bruit sismique. En effet, en cross-corrélant les trois composantes du bruit enregistré passivement à deux stations sismiques, on obtient le tenseur des corrélati...