Investigation of Migrating Seismicity in the Lithosphere of the Baikal Rift Zone

Аннотация

Based on “Catalog of earthquakes in the Baikal Region” (52700 earthquakes of representative energy classes K_P > 8, 1964–2013) at the angular sector of azimuthal analysis being q = 10° (±5 from azimuth α), quasilinear chains of earthquakes (M = 2143) were distinguished. As a result, the basic laws of the space–time and energy distribution of these chains in the lithosphere of the Baikal Rift Zone (BRZ) were established. The maximal quantity of chains was distinguished among weak earthquakes: a number of chains decreases as K_P grows following the law of frequency logM = f(K_P) is sloped at –0.48. Azimuths 50°–60° and 240°–260° correspond to the orientation of main seismogenic faults and the epicentral field in the BRZ. In space-time distribution of chains are observed maximum corresponding to high density epicenters and earthquake flow rates. In order to study seismicity migration, the index of migrating seismicity activity (ISMA), which is characterized at a given level of significance the seismicity migration/pseudomigration ratio has been used. The maps of the ISMA distribution over the territory and graphs of ISMA annual variations were constructed. The results obtained indicate a direct relationship between migrating seismicity in the BRZ and the locations and activations of rifting attractor structures (RAS).