TY - JOUR

T1 - Large paleoearthquakes and Holocene faulting in the Southeastern Gorny Altai: implications for ongoing crustal shortening in Central Asia

AU - Deev, Evgeny V.

AU - Panin, Andrey V.

AU - Solomina, Olga N.

AU - Bricheva, Svetlana S.

AU - Borodovskiy, Andrey P.

AU - Entin, Andrey L.

AU - Kurbanov, Redzhep N.

N1 - E. Deev thanks the IPGG SB RAS (State Assignment FWZZ-2022-0001) for help in organizing field research. GPR survey was conducted in the frame work of the IGRAS State Task FMWS-2024-0005. Geoscan Gemini UAV, Agisoft Metashape software and a hardware for aerial photography processing was provided by the Geoportal MSU Share-Use Center. We wish to thank N. Semenyak and V. Kuznetsova A. for aid in field and laboratory dendrochronological studies. The authors acknowledge A. Korzhenkov for his valuable comments during the excavation and initial study of Trench 3.

PY - 2024

Y1 - 2024

N2 - Shrinking of intermontane basins and expansion of their flanking ranges by reverse faulting and backthrusting in two counter-dipping systems is a typical mechanism of crustal shortening and mountain building in Central Asia. This mechanism is realized along the Kurai Fault Zone (southeastern Gorny Altai). Motions on two reverse fault systems maintained thrusting of the Kurai Range and the Kubadru Uplift on the Kurai Basin sediments and caused the growth of a foreberg before the mountain front. Forberg separates narrow Aktash Basin from the Kurai Basin. The paleoearthquakes were generated by reverse faults that delineate the foreberg. Analysis of the QuickBird satellite images, drone imagery, trenching, archaeoseismological research, radiocarbon dating, dendrochronology, and previous results show that eleven large (МW = 6.5–7.6) paleoearthquakes left traces as surface ruptures along the Kurai Fault Zone: twice before 7.5 ka BP, three events between 7.5 and 5.9 ka BP (7.0, 6.3, and 5.9–5.8 ka BP), one from 5.8 to 4.6 ka BP, four more at 4.6, 3.2, 1.5, and 1.3–1.2 ka BP, and the ultimate earthquake no older than 1450–1650 AD. The time difference between large earthquakes was from 200 to 1700 years. Surface faulting occurred mainly along the northern border of the foreberg where fault scarps are progressively younger northward and the Cenozoic sediments of the Aktash Basin thus become involved into uplift. GPR data to a depth of 12 m confirm the complex structure and slip geometry of the observed surface ruptures. The fault scarps are located < 1 km from the planned route of the gas pipeline from Russia to China, and the potential seismic hazard has to be taken into account in its design and construction.

AB - Shrinking of intermontane basins and expansion of their flanking ranges by reverse faulting and backthrusting in two counter-dipping systems is a typical mechanism of crustal shortening and mountain building in Central Asia. This mechanism is realized along the Kurai Fault Zone (southeastern Gorny Altai). Motions on two reverse fault systems maintained thrusting of the Kurai Range and the Kubadru Uplift on the Kurai Basin sediments and caused the growth of a foreberg before the mountain front. Forberg separates narrow Aktash Basin from the Kurai Basin. The paleoearthquakes were generated by reverse faults that delineate the foreberg. Analysis of the QuickBird satellite images, drone imagery, trenching, archaeoseismological research, radiocarbon dating, dendrochronology, and previous results show that eleven large (МW = 6.5–7.6) paleoearthquakes left traces as surface ruptures along the Kurai Fault Zone: twice before 7.5 ka BP, three events between 7.5 and 5.9 ka BP (7.0, 6.3, and 5.9–5.8 ka BP), one from 5.8 to 4.6 ka BP, four more at 4.6, 3.2, 1.5, and 1.3–1.2 ka BP, and the ultimate earthquake no older than 1450–1650 AD. The time difference between large earthquakes was from 200 to 1700 years. Surface faulting occurred mainly along the northern border of the foreberg where fault scarps are progressively younger northward and the Cenozoic sediments of the Aktash Basin thus become involved into uplift. GPR data to a depth of 12 m confirm the complex structure and slip geometry of the observed surface ruptures. The fault scarps are located < 1 km from the planned route of the gas pipeline from Russia to China, and the potential seismic hazard has to be taken into account in its design and construction.

KW - Gorny Altai

KW - Kurai Basin

KW - Kurai Fault Zone

KW - Paleoseismology

KW - archaeoseismology

KW - crust shortening

KW - ground penetrating radar

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85189832267&origin=inward&txGid=4f96227dec6ad86654863833191c85a4

UR - https://www.mendeley.com/catalogue/21af8de8-e401-37dd-a1d7-e10b53403c27/

U2 - 10.1080/00206814.2024.2333000

DO - 10.1080/00206814.2024.2333000

M3 - Article

JO - International Geology Review

JF - International Geology Review

SN - 0020-6814

ER -