Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

The distribution of more than three dozen strongest intraplate crustal earthquakes (with Mw ≥ 6.9) recorded in Central Asia (20° - 55° N, 55° - 120° E) for the 1971-2022 is considered, including the level of their aftershock activity and background seismicity in the field of velocity inhomogeneities of the medium. The analysis of background and aftershock seismicity with mb_(isc) ≥ 4.5 (from http://www.isc.ac.uk) was analyzed at the locations of focal zones (3°×3°). Within such zones, the total scalar seismic moment of background seismicity and aftershock sequences were calculated. Background seismicity was estimated for a 50-year time period before and after the main earthquake and its aftershocks. The duration of repeated shocks series is limited to one year. Against the background of the generalized seismotomographic model of Asia (at a depth of ~50 km), crustal foci of 24 strong earthquakes mainly seek toward zones of sign changes in P-wave velocity anomalies, three earthquakes are recorded in the low velocity zones and 4 in the high velocity zones. The largest values of the total scalar seismic moments released during the implementation of background seismicity are located within the negative P-wave velocities anomalies, as well as along the boundaries of sign changes in anomalies. When scalar seismic moments are released during aftershock and background activity, as well as the main event, the prevailing values remain within e+27. Increased values (e+28) are typical for zones of anomalies sign change and the area of positive anomalies of P-wave velocity. Low values ​​of total scalar seismic moments of background and aftershock events are observed in the focal zone of six sites (3°×3°). It has been suggested that the maximum magnitude for the 100-year period (1901-2022) was realized in these zones and the release of accumulated stresses could be carried out exactly through the strongest earthquakes.