BELARUS

. The review of annual seismicity in the territory of Belarus based on the data of two analog and seventeen digital stations is presented. 57 events with Кd=4.6–8.8 are recorded, all of them are located in the southern part of the territory, including the Soligorsk mining area. The maximum seismic energy released in March, August, October and November. The maximum number of earthquakes was observed from July to August and from October to November. The N(K) andΣE functions in 2014 were compared with those within 1983–2013. The number of events in 2014 is 1.34 times more than its average value for previous 31 years. The level of the seismic energy released in 2014 is 2.43 times more than in 2013 and 2.05 times lower than its long-time average value. The distributionof earthquakes by depth intervals showed that the earthquake foci are mostly located in the upper 20 km part of the Earth’s crust. However, the foci of 47 earthquakes are located at depths below 10 km. A slope of the graph showing the recurrence of the events with representative energy classes Кd=6–8 in 2014 was calculated. Its modulus γ=|0.48| is lower than the value γ=|0.5| in 2013. The distribution of all the events in 2014 is represented in real time. Quiet seismic periods and seismic activation periods were determined. The distribution of the seismic events by the hourly intervals showed the periods of the daytime and nighttime increase of the seismic event number. The maximum and minimum values N in the seismic event distribution by the days of the week were determined. The seismicity analysis has shown that the seismic activity level in 2014 was higher than that in 2013, but lower than its long-time average value.

An accurate relocation of the 2017 Ms 7.0 Sichuan Jiuzhaigou earthquake sequence and the seismicity analysis

<p>The 2017 Ms 7.0 Sichuan Jiuzhaigou earthquake occurred at the intersection of the Tazang, Minjiang, and Huya faults on the eastern margin of the Tibetan Plateau. Since it occurred on an unmarked blind fault, it is still a controversial issue whether the fault, which triggered the earthquake, was the extension of the East Kunlun fault or the northern branch of the Huya fault. Therefore, the accurate source location is of great significance for studying the deep distribution of seismogenic faults and seismicity analysis.</p><p>We have not only collected seismic phase arrival data recorded by 24 permanent stations and 6 temporary stations, but also picked up the seismic waveform data recorded by partial permanent stations in this study. Using absolute seismic location method and relative seismic location method, we relocated the earthquake events with magnitude greater than or equal to 1.0 occurred in the Jiuzhaigou area from August to December 2017. In order to ensure reliable data quality, we selected 23422 P-wave absolute arrival times, 24734 S-wave absolute arrival times and 124519 high quality P-waveform cross correlation data of 3449 earthquake events for relocation research.</p><p>The mean value of root mean square residuals of travel time of all earthquakes decrease from 0.21s to 0.08s after relocation. The average location errors in the E-W, N-S, and vertical directions are 0.11km, 0.12km, and 0.16km, respectively. Ninety-nine percent of the earthquake events are distributed in the depth range of 1-25 km, and the dominant distribution range is 5-15 km. The result shows that the earthquakes are distributed along the strike of northwest and southeast, and the Jiuzhaigou mainshock divided these events into two clusters: northwest and southeast. From the parallel strike section, we conclude that the depth of the northwest seismic cluster is shallow with the depth range of 2-15 km, and the depth of the southeast seismic cluster is deeper with the depth range of 6-18 km. Moreover, the number of aftershocks in the northwest cluster is greater than that in the southeast cluster, but after an M 4.9 aftershock occurred in the northwest cluster on the ninety-first day after the Jiuzhaigou mainshock, the number of aftershocks in the northwest cluster began to decrease. The result provides a basis for studying the seismogenic background and seismicity of the Jiuzhaigou earthquake.</p>

Analysis of the seismic process of the Bishkek geodynamic test site (Northern Tien Shan)

Various characteristics of seismic process on the territory of Bishkek geodynamic proving ground are considered. Seismicity analysis is performed on the basis of earthquake catalogue, according to KNET network data. The catalog includes more than 10,000 seismic events that occurred from 1994 to 2019. To describe the energy distribution function of earthquakes, the Gutenberg - Richter law was used, as well as the position of nonequilibrium thermodynamics with the use of Tsallis statistics, which generalizes classical thermodynamics to the case of nonextensive systems. It is shown that the flow of earthquakes on the territory of the Bishkek geodynamic proving ground is a system with memory and long-range spatial correlations, and the study region itself is characterized as seismically active. The following seismic process characteristics are distributed in space and in time: KSR seismogenic fracture parameter, seismotectonic deformation intensity, seismic activity, Tsallis parameter q and constants a, as well as a parameter characterizing the slope of the repeatability graph (b-value).