PALEOEARTHQUAKES IN THE UIMON BASIN (Gorny Altai)
a:2:{s:4:"TYPE";s:4:"HTML";s:4:"TEXT";s:192:"E.V. Deev1,2, I.D. Zol’nikov3,2, I.V. Turova1,2, G.G. Rusanov4, Yu.M. Ryapolova1,2, N.N. Nevedrova1,2, S.A. Kotler3";}
a:2:{s:4:"TYPE";s:4:"HTML";s:4:"TEXT";s:560:"1A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
3V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
4OAO “GornyAltai Survey Group,”, ul. Sovetskaya 15, Maloeniseiskoe Village, Altai Territory, 659370, Russia";}
Keywords: Палеосейсмология, первичные и вторичные сейсмодислокации, сильные древние землетрясения, Уймонская впадина, Горный Алтай, Paleoseismology, primary and secondary seismic deformations, large paleoearthquakes, Uimon basin, Gorny Altai
Subsection: GEOLOGY
Abstract
Paleoseismological studies confirm that the Uimon basin is thrust by its northern mountain border over the sediments along the active South Terekta fault. The latest motion along the fault in the 7-8th centuries AD induced an earthquake with a magnitude of Mw = 7.4-7.7 and a shaking intensity of I = 9-11 on the MSK-64 scale. The same fault generated another event ( M ≥ 7, I = 9-10), possibly, at ~16 ka, which triggered gravity sliding. The rockslide dammed the Uimon valley and produced a lake, where lacustrine deposition began at ~14 ± 1 ka, and a later M ≥ 7 ( I = 9-10) earthquake at ~6 ka caused the dam collapse and the lake drainage. Traces of much older earthquakes that occurred within the Uimon basin are detectable from secondary deformation structures (seismites) in soft sediments deposited during the drainage of a Late Pleistocene ice-dammed lake between 100 and 90 ka and in ~77 ka alluvium. The magnitude and intensity of these paleoearthquakes were at least M ≥ 5.0-5.5 and I ≥ 6-7.
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