Effective viscosity of the crust estimated from tilt measurements in the zone of the Major Sayan fault

Tilt variations of the Earth's surface measured in 1985-97 in the undergrou nd gallery of the Talaya seismic station (51.68 degrees N and 103.65 degree s E) are interpreted in terms of the Kelvin-Voigt model of viscoelastic cru st. Viscosity is estimated on the basis of time-dependent tilt variations i n the north-south direction. Effective viscosity was estimated at eta(s) = 3.10(18) Pa.s, proceeding from an empirically obtained delay of T = 6 years . The tectonic stresses corresponding to the measured tilt variations are a bout 2 MPa.