The high level seismicity of the Baikal rift zone and its spatial distribution in dense swarms and belts provide an opportunity to study the seismogenic behaviour of a continental lithosphere submitted to extension in an early stage. Using data from a regional seismological network, we analyze a significantly large set of events from an earthquake swarm located east of the nearly aseismic northern Baikal lake. We find that at least 10% of the well-constrained events are located in the lower crust or the uppermost mantle. The fault plane solutions of earthquakes within the crust define a NW-SE extensional stress regime perpendicular to the rift axis. Our results confirm the idea that zones of continental extension may exhibit significant rigidity. We propose to infer a migration of deformation from the northern Baikal lake to an initially stronger part of the lithosphere, i.e., the Barguzin rift and its extension to the east.