Time Variations in Earthquake Focal Mechanisms of the Racha-Dzhava Seismic Zoneстатья
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Дата последнего поиска статьи во внешних источниках: 10 февраля 2021 г.
Аннотация:In this publication we consider how local seismicity in the Racha-Dzhava seismic zone of the Caucasuschanged in time under the influence of large earthquakes that occurred in 1971–2011. In order to divide thewhole studied period into time intervals within which the total energy released by local earthquakes was summedup, we use the averaged focal mechanisms (obtained from the first P-waves arrivals) of earthquakes presented inthe Seismological Bulletins of the Caucasus. The averaged focal mechanisms were built according to the methodof K. Aki, in the terms of which a set of weak local earthquakes with a close distribution of the first P-waves arrivalsare considered one large earthquake. The change in averaged focal mechanisms with time is revealed; this isassociated with a change in tectonic stresses within the Racha-Dzhava zone. We also compare the changes indirections of tectonic stresses and the influence of strong earthquakes. It is shown that one of the factors of anabrupt and short-term change in a stress state and in a local seismicity level is an impact of distant strong andcatastrophic earthquakes. The results can be interesting for understanding some aspects of local seismic activityand the causes of changes in the stress field and the activity of seismic process in the Racha-Dzhava seismic zone.