DEEP STRUCTURE OF THE BAIKAL RIFT FROM MULTIWAVE SEISMIC EXPLORATIONS

Abstract

From joint analysis of compressional and shear waves generated by shots and by local earthquakes, new specific features are established for the model of the Earth's crust and upper mantle in the Baikal rift zone. Poisson ratio values at different depth levels are estimated. These values are shown to be much higher over the territory under investigation than their counterparts in the adjacent southern areas of the Siberian platform.Prime attention is paid to the technique and initial results of highly detailed works carried out by means of P- and S-wave deep seismic soundings on the north-eastern flank of the Baikal rift (Muya depression). A 3-dimensional seismic model of the upper part of the Earth's crust is constructed. It includes the domain where the foci of local earthquakes are concentrated. Due to joint use of deep waves with various polarizations, essentially new seismic information on the properties of the medium is obtained.