ACTIVE TECTONICS AND PALEOSEISMICITY OF THE EASTERN ISSYK-KUL BASIN (Kyrgyzstan, Tien Shan)
A.M. Korzhenkov1,2, E.V. Deev3,4,5, I.V. Turova3,4, S.V. Abdieva2, S.S. Ivanov6, J. Liu7, I.V. Mzeika8, E.A. Rogozhin1, A.A. Strelnikov1, A.B. Fortuna2, M.T. Usmanova9
1O.Yu. Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, ul. Bol’shaya Gruzinskaya 10, Moscow, 123995, Russia
2Kyrgyz Russian Slavic University, ul. Kievskaya 44, Bishkek, 720000, Kyrgyzstan
3Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
4Novosibirsk State University, ul. Pirogova 1, Novosibirsk, 630090, Russia
5Institute of Geography, Russian Academy of Sciences, Staromonetnyi per. 29, Moscow, 119017, Russia
6Zh. Balasagyn Kyrgyz National University, ul. Frunze 547, Bishkek, 720033, Kyrgyzstan
7Institute of Geology, China Earthquake Administration, Huayanli St. 1A, Chaoyang District, Beijing, 100029, China
8State Science Institute Nature Research Centre, Akademijos St. 2, Vilnius, LT-08412, Lithuania
9G.A. Mavlyanov Institute of Seismology, ul. Zulfiyakhonum 3, Tashkent, 100128, Uzbekistan
Keywords: Intrabasinal uplifts, large paleoearthquakes, fault scarps, seismites, South Issyk-Kul fault, Karkara fault, eastern Issyk-Kul basin, northern Tien Shan
Abstract
The Malyi Orgochor, Orgochor, Birbash, Sukhoi Ridge, Ichketosma, and Tosma uplifts in the eastern Issyk-Kul basin are fault-related anticlinal folds composed of Neogene and Quaternary sediments involved in tectonic movements. The folds have asymmetric transversal profiles, with low-angle southern limbs and steep northern limbs cut by segments of the South Issyk-Kul and Karkara reverse faults reactivated in the late Quaternary. The location and geometry of the two faults, which both show reverse and left-lateral strike slip components, correspond to neotectonic propagation of deformation from the Terskey-Ala-Too Range over almost the whole eastern Issyk-Kul basin. Judging by primary and secondary coseismic surface deformation in the area, the South Issyk-Kul and Karkara faults repeatedly generated large earthquakes ( M ≥ 7, I ≥ 9) in the Late Pleistocene and Holocene. According to trenching results, the historical earthquakes that occurred in the first and 10-11th centuries accommodated motions on the South Issyk-Kul fault. The new seismotectonic and paleoseismicity data from the eastern Issyk-Kul basin provide updates to its seismic potential.
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