Paleoseismological investigation of the Kichera Fault Zone in the northern Baikal region

Abstract

In the recent structure of the Baikal Rift Zone, the Kichera Fault serves as the northwestern boundary of the Angara-Kichera aggradation depression. A seismotectonic scarp 60 m high was formed as a result of normal faulting during the late Pleistocene and Holocene. The erosion-aggradation and seismic landforms testify to the nonuniform growth of this scarp. To study the character of the seismic activity in the Kichera Fault Zone, we excavated two trenches across the seismotectonic scarp. The Holocene stage of the seismotectonic activation within the fault zone and the preceding period of relative quiescence were outlined from the character of the deformations in the trench sections and previous geomorphic investigations. According to our preliminary estimations, the active stage that started at the end of the late Pleistocene and that has remained incomplete until now was accompanied by at least three rupture-forming earthquakes.