Geophysical processes and biosphere: article

Аnnotation: Morphostructures and paleoseismicity were studied on the southern slope of the Kungei Ala-Too Ridge (Northern Tien Shan). It has been established that the main seismogenic structures in the Late Pleistocene and Holocene are adyr – foothill faults of reverse-thrust, strike-slip and fault dy-namics. With a general thrusting of blocky folds of the base to the south – towards the Issyk-Kul depression, there are also underthrusts, with the direction of movement to the north. The seismic activity of the past along the adyr faults is expressed by single seismic scarps, as well as whole staircases of upturned alluvial-proluvial and fluvioglacial surfaces, upturned in the hanging limbs of disjunctives. In addition to the easily identifiable vertical component of slips along the faults, we have also identified significant horizontal slips, often times a multiple of the vertical ones. In addition, a unique structure on the slope of the Kungei ridge was studied – a neotectonic ramp gra-ben bounded from the south and north by counter thrusts. These disjunctives were also studied with the help of trenching. It was found that in the middle – second half of the Holocene there were 3 strong morphogenetic events along the South Tegersky and 3 strong earthquakes along the North Tegerek adyr faults. Ages for 4 strong earthquakes were determined by radiocarbon method. The maximum ages of the first three events: 3970–3755 years. BC, 220–405 and 1380–1450, the mini-mum age of the last event is 1720–1815. The magnitudes of historical and paleoearthquakes along the studied adyr faults range from M = 6.6–6.9±0.5 (South Tegerek fault) to M = 6.8–7.4±0.5 (Kul-tor adyr fault). Seismic events of similar magnitudes lead to deformations on the earth's surface and in building structures, which can be estimated on a macroseismic scale of I ≥ IX points. The materials obtained by us can be used for a comparative analysis of similar post-platform orogens in Russia, such as the Altai and Sayan Mountains, as well as in compiling the new map of the General seismic zoning of the Kyrgyz Republic.