Some results of research of geotectonic conditions, geodynamics and modern seismicity East Caucasus

Abstract

The analysis of seismotectonic conditions and modern seismicity of the East Caucasus is carried out. Based on a detailed analysis of the accumulated geological and geophysical materials of the industrial enterprises “Dagneft”, Dagneftegaz, “Dagestangeologia”, the Institute of Geology of Dagestan Scientific Center of the Russian Academy of Sciences and large-scale geological, tectonic, geological and structural maps of I. O. Brod, L. A. Vardanyants, V. P. Rengarten, N. N. Rostovtsev, Yu. G. Leonov and others, as well as small-scale maps of A. I. Letavin, V. L. Galin, D. G. Sharafutdinov, G. D. Butorin, G. G. Gasanguseinov, D. A. Mirzoev, V. M. Pirbudagov and many others, a new scheme of fault-block tectonics and a generalized tectonic zoning scheme with elements of fault-block tectonics on a scale of 1: 500 000 have been compiled. According to the results of the research, prediction of zones of possible seismic sources (PSS) was performed. The new generalized scheme reflects all known major disjunctions and blocks of the basement and sedimentary cover of the Dagestan sector of the Eastern Caucasus at the present stage of its study and serves as a basis for predicting endogenous processes, localizing sources of stress and identifying potential seismic sources. During the last 30-40 years, quite a lot of strong earthquakes have been recorded here by instrumental means, including: Dagestan - 14.05.1970 (8-9 points), Salatau - 23.12.1974 (7 points), Buynaksk - 9.01. 1975 with the magnitude in the epicenter equal to 8 points, the Kumtorkala earthquakes - (31.01. with the magnitude of 7 points and 21.02., 14.04.1999), etc. The spatial distribution of earthquake epicenters shows that, in addition to the marked modern high-seismic zone, four more seismically active zones were identified in the northeast segment of the Eastern Caucasus: Derbent, Kubachi-Deybuk-Harbuk-Urkarakh, Argun-Gudermes-Khasavyurt and Lagodekhi-Belokany-Zakatalinsk. Seismic cycles in these zones have a different frequency and duration. According to the analysis of the modern seismicity, it was concluded that seismic activity has increased over the past 30-40 years and some signs of a possible preparation of a strong earthquake in the near future revealed. One of the signs of probable preparation of a strong earthquake is a reduction in dispersion (decrease) between the maximum and minimum magnitudes for the studied period of time.