Experimental models for the Earth's crust deformations in the southwest ofthe 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 meas urements permitted estimation of deformations in major directions. Shearing strains showed maximum annual average changes in value - 3.10(-6). Deviato ric stress, 0.6 MPa (6 bars), was estimated from the quick changes caused b y a violent earthquake (M = 6.5). According to the data obtained by an abso lute GABL-M laser gravimeter, the stability of the gravity field remained c onstant 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. T o characterize the Talaya region, the Budiansky-Amazigo models for the lith osphere and the Elsasser model for the lithosphere and asthenosphere are an alyzed. The best results of deformation measurements were obtained when use d the Elsasser two-layer model with the efficient viscosity of the asthenos phere of 1.2.10(20) Pas. This viscosity and the rate of the Earth's crust m ovements estimated at the GPS station, Irkutsk, (3 cm/year, 101 degrees N) permitted evaluation of deviatoric stress in the lithosphere in the south o f the Siberian Platform - 18 MPa (180 bars).