Experimental models for the Earth's crust deformations in the southwest of the Baikal Rift Zone

In 1990-95, deformations and the absolute values of gravity in the adit of the Talaya seismic station were measured. The multiazimuthal scheme of measurements permitted estimation of deformations in major directions. Shearing strains showed maximum annual average changes in value - 3.10(-6). Deviatoric stress, 0.6 MPa (6 bars), was estimated from the quick changes caused by a violent earthquake (M = 6.5). According to the data obtained by an absolute GABL-M laser gravimeter, the stability of the gravity field remained constant within the measurement error of 0.5 - 1.0 mu Gal. The maximum rate of the vertical movements of the Earth's crust is estimated at 1 mm/year. To characterize the Talaya region, the Budiansky-Amazigo models for the lithosphere and the Elsasser model for the lithosphere and asthenosphere are analyzed. The best results of deformation measurements were obtained when used the Elsasser two-layer model with the efficient viscosity of the asthenosphere of 1.2.10(20) Pas. This viscosity and the rate of the Earth's crust movements estimated at the GPS station, Irkutsk, (3 cm/year, 101 degrees N) permitted evaluation of deviatoric stress in the lithosphere in the south of the Siberian Platform - 18 MPa (180 bars).