Информационная система "Конференции"



II International Workshop
ACTIVE GEOPHYSICAL MONITORING
OF THE EARTH LITHOSPHERE

September 12-16, 2005, Novosibirsk, Academgorodok

Attention!!!

We inform, that term of submission of theses and reports is prolonged till June, 30.


Abstracts


SV and SH wave velocities in the upper mantle of Central Asia from group velocities of Rayleigh and Love waves

T.B.Yanovskaya, V.M.Kozhevnikov, O.V.Martyugina, O.A.Solovei

Sankt-Petersburg State University,
Institute of the Earth’s crust SD RAN (Irkutsk)

Group velocity dispersion curves for Love and Rayleigh waves are determined by frequency-time analysis in the period range 10-150 s along the paths across Central Asia and Siberia. They are supplemented by the data provided by the Center for Imaging the Earth's Interior of the University of Colorado at Boulder, so that the total number of the paths amounts to 2500 - 4000 depending on the period. The group velocities are mapping for individual periods using the 2D seismic tomography method. This allowed us to determine local dispersion curves in some points of the territory under investigation. The local dispersion curves of Love and Rayleigh waves are inverted to vertical velocity sections – jointly for two types of waves, as well as separately for SV waves (from Rayleigh waves) and for SH waves (from Love waves). It is found that SH velocity in the crust and upper mantle is higher than that for SV waves up to the depth of ~ 300 km. The averaged anisotropy coefficient was determined from the SH and SV velocities in the depth intervals from Moho up to 100 km, from 100 up to 200 km, and from 200 up to 300 km. The maps of averaged anisotropy coefficient are drawn for these depth intervals. Maximum anisotropy (up to 6%) is observed in the low-velocity zone (asthenosphere); the more pronounced is the low-velocity zone, the larger is anisotropy. Lateral distribution of the anisotropy coefficient correlates with the age of tectonic structures: the anisotropy is maximum in the regions of present orogeny, whereas at stable platforms it is negligible. The average velocity (SH+SV)/2 in asthenosphere in the depth interval 100-200 km is minimum where the anisotropy coefficient is maximum.

Note. Abstracts are published in author's edition


Last update: 06-Jul-2012 (11:44:54)