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Russian Geology and Geophysics

2009 year, number 3

Hierarchy of earthquakes in the Baikal rift system: implications for lithospheric stress

A.V. Klyuchevskii, V.M. Dem'yanovich, V.I. Dzhurik
Institute of the Earth's Crust, Siberian Branch of the RAS, 128 ul. Lermontova, Irkutsk, 664033, Russia
Keywords: medium-size and large earthquakes; source parameters, slip geometry; earthquake mechanism; lithospheric stress; Baikal rift system
Pages: 206-206


We investigated space-time lithospheric stress patterns of the Baikal rift system according to the hierarchy of earthquakes using mechanisms of 265 K P ≥ 10 events recorded from 1950 to 1998 and seismic moments of 802 K P ≥11 events from 1968 to 1994. The lithosphere of the region was confirmed to undergo rifting with mostly normal-slip events, while local areas of frequent strike-slip and reverse motions may record stress heterogeneity. The dominance of rifting, although being evident in the stress dynamics, is unstable, which is indicated by increase in strike-slip and reverse motions to as many as normal slip events in the latest 1980s-earliest 1990s. The lithospheric stress patterns inferred from seismic-moment data are generally consistent with those derived from the classical focal mechanism method. The suggested approach of seismic zoning according to earthquake slip geometry may provide a more reliable background for successful mitigation of seismic hazard in the region.