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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. [ABSTRACT FROM AUTHOR]

This work aims to verify and correct the boundary between two landscapes--moraine and outwash plain--delineated earlier by the classical landscape approach. The initial interpretation of the boundary caused controversy due to the appearance of the thermokarst depression in the outwash landscape. The lithological structure is one of the main factors of landscape differentiation. The classical approach includes drilling to obtain the lithological and sedimentary data. However, the boreholes are usually shallow, while geophysical methods allow to look deeper into the subsurface and improve our knowledge about lithological structure and stratigraphy. In this study, we use ground-penetrating radar with a peak frequency of 250 and 50 MHz and detailed electrical resistivity tomography (with 1 m electrode spacing) in addition to the landscape mapping and drilling to correct the landscape boundary position. We conclude that it is primarily defined by the subsurface boundary between lithological complexes of clayish moraine deposits and sandy outwash deposits located at 7 m depth. Moving the boundary to the northeast by 70-100 m from the current position removes inconsistencies and clarifies the history of the area's formation in the Quaternary. [ABSTRACT FROM AUTHOR]

Palaeoseismology studies the footprints of ancient earthquakes to improve the knowledge about the modern seismicity of the territory. A ground‐penetrating radar (GPR), among other geophysical methods, is used for quick determination of shallow stratigraphy – displaced, oblique layers within the fault zone. GPR data interpretation from diverse and complex reflection patterns of the fault zone heavily depends on the interpreter's experience. The range of different fault zone parameters in which this method can be successfully applied has not yet been investigated. We used a numerical simulation of GPR data to determine how GPR images the elements of faults (fault plane, hanging wall, footwall) in comparison with other reflections. Furthermore, we studied which parameters have the most significant impact on GPR wave patterns. We performed a series of numerical models of a fault, changing its geometry with increasing complexity from elementary models to realistic ones. The resulting synthetic profiles allowed finding specific GPR signatures from the fault plane, the hanging wall and the footwall. We collected field GPR data from two different fault zones and examined them for verification. [ABSTRACT FROM AUTHOR]