EARTHQUAKE FOCAL MECHANISMS AND SEISMOTECTONIC DEFORMATION IN THE KAMCHATKA-COMMANDER REGION

Abstract

The system of stresses in the lithosphere (0–59 km) and upper asthenosphere (60–150 km) was analysed on the basis of focal-mechanism data for events of M > 5.0 in 1964–1982. The zoning was made considering types of faulting and predominant stress systems. Four uniformly-stressed zones have been identified within the lithosphere and two zones within the upper asthenosphere. The deep distribution of types of faulting and stresses shows the presence of a double seismic focal zone under Kamchatka.Schemes of seismotectonic-deformation (STD) rate-tensor components were dran separately for the lithospheric and asthenospheric layers. To this end, data on individual and averaged focal-mechanism solutions and regional seismic moment-energy class relationships were used. The average STD rate for the lithosphere is 10−9 yr−1, and for the upper asthenosphere 10−10 yr−1. Vertical and horizontal components of STD are of the same order.