The presence of fault scarps is a first-order criterion for identifying active faults. Yet the preservation of these features depends on the recurrence interval between surface rupturing events, combined with the rates of erosional and depositional processes that act on the landscape. Within arid continental interiors single earthquake scarps can be preserved for thousands of years, and yet the interval between surface ruptures on faults in these regions may be much longer, such that the lack of evidence for surface faulting in the morphology may not preclude activity on those faults. In this study we investigate the 50 km-long ‘Toraigyr’ thrust fault in the northern Tien Shan. From palaeoseismological trenching we show that two surface rupturing earthquakes occurred in the last 39.9±2.7 ka BP, but only the most recent event (3.15–3.6 ka BP) has a clear morphological expression. We conclude that a landscape reset took place in between the two events, likely as a consequence of the climatic change at the end of the last glacial maximum. These findings illustrate that in the Tien Shan evidence for the most recent active faulting can be easily obliterated by climatic processes due to the long earthquake recurrence intervals. Our results illustrate the problems related to the assessment of active tectonic deformation and seismic hazard assessments in continental interior settings

The 11 July 1889 Chilik earthquake (M_w8.0–8.3) forms part of a remarkable sequence of large earthquakes in the late nineteenth and early twentieth centuries in the northern Tien Shan. Despite its importance, the source of the 1889 earthquake remains unknown, though the macroseismic epicenter is sited in the Chilik valley, ~100 km southeast of Almaty, Kazakhstan (~2 million population). Several short fault segments that have been inferred to have ruptured in 1889 are too short on their own to account for the estimated magnitude. In this paper we perform detailed surveying and trenching of the ~30 km long Saty fault, one of the previously inferred sources, and find that it was formed in a single earthquake within the last 700 years, involving surface slip of up to 10 m. The scarp‐forming event, likely to be the 1889 earthquake, was the only surface‐rupturing event for at least 5000 years and potentially for much longer. From satellite imagery we extend the mapped length of fresh scarps within the 1889 epicentral zone to a total of ~175 km, which we also suggest as candidate ruptures from the 1889 earthquake. The 175 km of rupture involves conjugate oblique left‐lateral and right‐lateral slip on three separate faults, with step overs of several kilometers between them. All three faults were essentially invisible in the Holocene geomorphology prior to the last slip. The recurrence interval between large earthquakes on any of these faults, and presumably on other faults of the Tien Shan, may be longer than the timescale over which the landscape is reset, providing a challenge for delineating sources of future hazard.

The Tien Shan accommodates a significant portion of the India‐Eurasia N‐S convergence. In its northern part a zigzag pattern of mountain ranges bounds the western Ili Basin. The role of this basin in the overall shortening and the regional kinematics is not well understood. Geodetic data and instrumental seismicity are not sufficient to infer the role of individual faults and fault systems. We analyze GPS data and earthquake slip vectors and present the results of fault mapping based on remote sensing and field campaigns in the western Ili Basin. These observations indicate that E‐W thrust faults are active at the basin margins, and oblique and strike‐slip faults, both in the basin and in the Paleozoic rocks within the mountain ranges, have been active in the Late Quaternary. We propose a regional tectonic model in which the left‐lateral strike‐slip faults at the NW margin of the basin accommodate ~3‐mm/year NE‐SW shear. Smaller right‐lateral oblique faults transfer the motion in between the left‐lateral faults, and also take up shortening by rotations about vertical axes. We see the onset of internal deformation within the Ili Basin, although it has a strong basement. Our kinematic model is consistent with geodetic data, earthquake seismology, historical, and prehistorical surface faulting, and describes the first‐order features of active deformation that can be observed in the northern Tien Shan. Our study illustrates the importance of combining these different data sets to understand the regional tectonics.

We demonstrate that a continental interior reverse fault is deforming by aseismic creep, presently, and likely also in the long term. The Karkara Rangefront Fault, part of the larger Main Terskey Front, forms the northern boundary of the high Terskey Tien Shan in southeastern Kazakhstan and is a mature structure with evidence for high slip rates throughout the late Cenozoic. Combining field studies with a satellite stereo-image derived digital elevation model (2 m resolution), we map a series of fluvial terraces along the rangefront which are uplifted by up to ∼300 m above the present river level. Radiocarbon ages from one catchment constrain the ages of the lowermost two terraces to be ∼4–5 ka and ∼10–15 ka, consistent with prominent, regionally extensive terraces observed elsewhere in the Tien Shan. Based on conservative estimates for the fault dip under the displaced terraces, we estimate a slip rate along the fault plane of 3.5$$^{+1.7}_{-0.4}$$ mm yr^–1 on the Karkara Rangefront Fault and a further >0.8 mm yr^–1 on a fold structure in the Kegen basin that we infer is driven by a detachment from the main rangefront. We therefore estimate a minimum shortening rate across the rangefront of 1.1–3.3 mm yr^–1. Elastic modelling of the regional GPS velocity field suggests that the fault is presently creeping at ∼3 mm yr^–1 (horizontal shortening), consistent with the upper limit of our Late Quaternary slip rate estimate. This is the fastest known slip rate in the northern Tien Shan and the only individual structure resolved in the regional velocity field. At present the fault is accumulating minimal strain, and there is evidence in the geomorphology that this creep is sustained in the long term, but whether or not it is also capable of generating earthquakes requires further study.

In 2021–2023 a task set before the seismologists was to conduct work on seismic zoning of the east Kazakhstan territory. The seismic stations network of that region is represented by two seismic arrays and two three-component stations of the IGR NNC RK and two three-component stations of the SEME MES RK. The work describes the parameters of the IGR NNC RK stations, estimates its capabilities in recording the events of different magnitudes at various distances. In 2002– 2020 the IGR NNC RK stations recorded almost 34000 events. After discrimination of explosions and its removal from the catalogue of seismic events the map of earthquakes epicenters at the east Kazakhstan territory that includes 28000 earthquakes was constructed. This material is one of the main informational components for seismic hazard assessment in this region.

Long-term and present-day crustal deformation in the northern Tien Shan is poorly known, but is a key to understanding the mode of lithospheric deformation deep within the continental interiors, as well as the hazards posed by the slow-moving intraplate faults. Driven by the India-Asia collision, the NW-SE strike-slip faults and the E-W range-front thrust faults in the interior of Tien Shan together accommodate about 15-20 mm/yr of shortening. Here we focus on the NW-SE striking Dzhungarian fault (DZF) and the E-W striking Lepsy fault (LPF), which are large oblique strike-slip faults bounding the Dzhungarian Alatau, northern Tien Shan. Two large historical earthquakes in ~1716 and 1812 (Mw 8) were recorded in this region, and clear fault traces as well as scarps are visible from satellite images along some of the main faults. However, their geometries, slip rates, mode of deformation, expected earthquake magnitudes and recurrence interval have not been studied in details. A previous study suggested that the LPF ruptured in a seismic event around 400 yrBP that might be the 1716 earthquake known from historical records. Offsets of over 15 m were found over a fault length of 120 km, indicating a magnitude in the range Mw 7.5-8.2. The slip to length ratio for the LPF is unusally high, suggesting either that faults in this region are capable of generating very large earthquakes for a given fault length, or that the rupture length is underestimated.Using a combination of high-resolution digital elevation models (DEMs) and orthophotos from High Mountain Asia (NASA), Pleiades optical imagery (CNES), drone photos and multi-temporal interferometric synthetic-aperture radar (InSAR) from the Sentinel-1 satellites, we identify the geomorphic signatures and quantify the long-term and short-term strain accumulation along the faults. The ~400 km DZF shows evidence for relatively ‘fresh’ rupturing along much of its length. We calculate an average lateral slip per event of 9.9 m from offset stacking analysis, which underlines the potential future large earthquakes on this fault. The proximity of the DZF and LPF ruptures and equivalent level of preservation opens the possibility that they were formed in a single earthquake event, with a moment-magnitude greater than 8. We also present estimates of long-term and short-term rates of slip across the DZF in order to estimate average recurrence intervals and to build a kinematic model of the faulting in the Northern Tien Shan.