SOME FEATURES OF SEISMIC REGIME IN THE KAMCHATKA REGION: SEISMIC ACTIVATION IN 2000–2021

This paper mainly considers seismicity in the Kamchatka region. Based on 60-year-long instrumental observations, there were seven seismic layers identified according to depth distribution of seismic energy. For each layer, there were obtained seismicity characteristics: a number of events in a layer, depth of peak energy penetration, total energy in a layer, slope of a trend line in recurrence plots, ratio of the total energy of earthquakes with a K-value greater than 14 to that of earthquakes with a K-value between 10 and 14. The slope of the trend line in recurrence plots decreases with depth from 0.63 to 0.36. Almost half of the total seismic energy fell within the depth greater than 50 km. The change in seismic layers during the instrumental observations is shown on plots of deviations from uniform increase in the accumulation of cumulative energy over time and cumulative total amount of events. The movement on the plots allows making an assumption about the constancy of subduction velocity and stability of background seismic energy dissipation for the Kamchatka region on the intervals with a linear increase in the accumulation of cumulative energy over time. An increase in the accumulation rate of the cumulative total amount of earthquakes at depths greater than 550 km was subsequently followed by an increase in the accumulation rate of the cumulative total amount of events in 0–35 and 80–130 km layers. It is shown that since the 2000s there has been an increase in seismic activity in seismic focal zone of the Kamchatka region.