AIGULAK FOCAL AREA AS A RESULT OF THE IMPACT OF THE 2003 CHUI EARTHQUAKE ON GORNY ALTAI
A.F. Emanov1, A.A. Emanov1,2, I.S. Novikov3, E.A. Gladyshev1, A.V. Fateev1,2, P.O. Polyansky1, E.V. Shevkunova1, R.A. Ershov1, V.V. Arapov1, A.A. Krivov4
1Altai‐Sayan Branch of Geophysical Survey of the Russian Academy of Sciences Novosibirsk, Russia
2 V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences,Novosibirsk, Russia
3 Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences Novosibirsk, Russia
4 Novosibirsk Higher Military Command School of the Ministry of Defense of the Russian Federation, Novosibirsk, Russia
Keywords: Aigulak earthquake, Gorny Altai, fault structure, aftershocks
Abstract
Years after the Chui earthquake of 2003, geological structures adjacent to the focal area of the Chui earthquake are seismically activated. The Aigulak focal area is one of them, but energetically the most pronounced. Detailed studies have been carried out with the network of stations of the Altai seismological polygon, supplemented by temporary stations. The region was activated in the form of a local and compact structure measuring 10km×10km with focal depths from the first hundred m to 20km. The focal area is not a further activation along the same fault with the Chui earthquake, but is located on a subparallel fault in the nodal region with its branching into three faults. The seismic activation of the Aigulak focal area is not an aftershock process after a major earthquake, but is an activated structure with a dynamically changing seismic process. An intensive process has formed since the earthquake in 2012 with ML=6.1 with a gradual decrease in the number of earthquakes, and in 2019 the Aigulak earthquake with ML=5.5 occurred with a very strong aftershock process after it. The results of an area study of earthquake density in the focal zone indicate a change in the regime over time: from chaotic to self-organizing along short faults. It is suggested that the focal area has not reached the maximum level of seismic energy release.
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