Correlation of earthquake occurrence rates in the Baikal region and mongolia: Episodes of synchronism

Variations in annual numbers of earthquakes (the earthquake occurrence rate) that hit the Baikal region and Mongolia during the period from 1964 through 2001 are studied in this work. Correlation analysis of the different-length series of annual numbers N of earthquakes of representative energy classes makes it possible to reveal the effects of synchronous changes in the earthquake occurrence rate in seven regions and eleven areas in the Mongolia-Baikal region, located far apart. The analysis of the shock occurrence rate revealed episodes of short-period synchronization of seismic processes in the Mongolia-Baikal region at the end of the 1960s, early in the 1980s, and in the middle of the 1990s. The episode of synchronization in the earthquake occurrence rate in the early 1980s is observed in all the territories under study, but the episode at the end of the 1960s is less distinctly seen in Mongolia and is revealed mainly in the data series with a length of three years. The synchronization in the seismicity in Mongolia and in the southern PreBaikal region in 1995 requires further investigations, involving the dynamic parameters of the earthquake sources. The observed synchronism in the annual number of earthquakes indicates that the seismic processes become active nearly simultaneously over the huge territory of the Mongolia-Baikal region and produce a short-term coherent change in the shock occurrence rate in the spatial-temporal distribution of the seismicity. The observed spatial and temporal correlation in the seismicity is a sign of the seismogenic link between the Baikal region and Mongolia.