TRANSVERSE FAULTS OF THE EASTERN CAUCASUS AND THEIR MANIFESTATIONS IN SEISMICITY

T.Y. Mammadli1, E.A. Rogozhin2

1 Republican Seismic Survey Center of Azerbaijan National Academy of Sciences, Baku, Azerbaijan

2 Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia

Abstract. The features of the spatial distribution of earthquake sources in the Eastern Caucasus (within the borders of Azerbaijan and the Chechen Republic of the Russian Federation) are analyzed. According to the method developed in recent years to identify seismogenerating zones of deep faults by manifestations of weak seismicity, a number of transverse faults extending in the diagonal direction (SW-NE) are established. They, like others, longitudinal relative to the strike of the mountain-folded structures of the Greater Caucasus faults, do not demonstrate the same seismic activity throughout. Seismically active are only their individual segments of small length. Transverse faults are deep and cross the earth's crust at its full thickness. Some of them are associated with sources of destructive earthquakes. For example, on the Northern slope of the Greater Caucasus, `in the eastern part of the Chechen Republic in 2008, there occurred the Kurchaloy earthquake with M=5.6, which caused human losses and destruction. It’s source was confined to the deep fault of the North-Eastern strike, limiting the mountain ledge "Dagestan wedge" from the North-West. On the Western periclinal of the Greater Caucasus, in the area of Anapa transverse flexure-breaking zone also took place the strong Anapa 1996 and Nizhnekubanskoe-II 2002 seismic events. Of course, the longitudinal (Caucasian strike) tectonic faults also demonstrate weak and high magnitude seismicity. Such faults were associated with the sources of the strongest earthquakes of the late 20th and early 21st centuries (Dagestan 1970, Chernogorsk 1977, Racha 1991, Barisakho 1992, Baku 2000, Oni 2009). But the transcaucasian disjunctives for a long time have been underestimated by seismologists and seismotectonists as hazardous seismogenic structures. In the result of their activation may be serious consequences. The article shows the role of such faults in the distribution of strong and weak seismicity.

Keywords: Caucasus, fault, seismogenic zone, earthquakes, seismic activity, structure and seismic sections

About the authors

MAMMADLI Tahir Yadigaroglu – doctor of geological and mineralogical sciences, head of the Department of seismology, the Republican Seismic Survey Center of Azerbaijan National Academy of Sciences of Azerbaijan. Azerbaijan, AZ1001, Baku, 25 Nigar Rafibeyli street. Tel.: +7 (99412) 497-06-98. E-mail: m-tahir@mail.ru

ROGOZHIN Evgeny Aleksandrovich – doctor of geological and mineralogical sciences, professor, head of the Coordination Prognostic Center, Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences. 123242, Moscow, Bolshaya Gruzinskaya str., 10, b. 1. Тел.: +7 (499) 254-87-15. E-mail: eurog@ifz.ru

Cite this article as: Mammadli T.Y., Rogozhin E.A. Transverse faults of the Eastern Caucasus and their manifestations in seismicity, Voprosy Inzhenernoi Seismologii (Problems of Engineering Seismology), 2018, Vol. 45, No. 2, pp. 61–71. [in Russian]. DOI: 10.21455/VIS2018.2-5

English translation of the article will be published in Seismic Instruments, ISSN: 0747-9239 (Print) 1934-7871 (Online), https://link.springer.com/journal/11990), 2019, Volume 55, Issue 2.