The northward growth and expansion of the Shanxi rift system (SRS) are key to understanding the geodynamic evolution of the northeastern Ordos block. Previous studies have suggested that Shanxi rift activity weakens north of the Daihai-Huangqihai Basin under the influence of the EW-strike Zhangjiakou-Bohai tectonic zone. In this study, remote sensing and field investigations reveal an similar to 100 km long prominent linear structure north of the Jining Basin in the northeastern Ordos block. Three high-density electrical resistivity tomography (ERT) profiles across this structure identify this region as the North Jining Basin Fault, NE-striking, SW-dipping normal fault that structurally controls the northern margin of the basin, exhibiting typical fault depression characteristics and latest activity in the Holocene. Geological evidence confirms that the fault offsets mid-Holocene sediments with a vertical displacement of similar to 2.7 m. Combined with the spatiotemporal evolution of the Shanxi rift system, these findings suggest that the northeastern boundary of the rift remains active and continues to propagate northward, with the North Jining Basin Fault representing northward expansion of the extensional regime of the Shanxi rift.

The geometric configurations and kinematic behavior of seismogenic faults fundamentally govern the spatial distribution of earthquake-triggered landslides, where quantifying their mechanisms dominating occurrence probability poses a core challenge for advancing predictive accuracy. Focusing on the 2008 Wenchuan earthquake and its main rupture zone (Beichuan-Yingxiu Fault), a thrust-strike-slip structure exhibiting along-strike dip variations ranging from similar to 43 degrees in the south to near-vertical in the north, this study establishes a probabilistic framework integrating fault geometry with five controlling factors, including distance to fault, peak ground acceleration (PGA), slope, local relief, and lithology, using a comprehensive EQTL inventory. Using multivariate nonlinear regression (MNR) and random forest (RF) modeling, we elucidate the fault dip's regulatory role in earthquake-triggered mechanisms. Key findings indicate that low-dip faults (43 degrees-53 degrees) drive concentrated hanging-wall landslides, characterized by PGA saturation > 0.5 g, high sensitivity to slopes >30 degrees, and abrupt acceleration beyond 500 m relief; conversely, high-dip faults (59 degrees-89 degrees) exhibit bilaterally symmetric distributions with PGA triggering at 0.2 g, pronounced slope sensitivity >20 degrees, and peak probability at 500-1000 m relief followed by post-peak decline. Factor importance analysis confirms distance to fault and PGA as primary predictors; however, their influence is dynamically modulated by dip angle. The RF model outperforms MNR (AUC >0.90 versus MNR's high-dip AUC = 0.728). Blind testing with the 2013 Lushan earthquake (thrust-type) and 2017 Jiuzhaigou earthquake (strike-slip) confirms the model captures hanging-wall concentration and bilateral symmetric distributions, demonstrating cross-fault adaptability.

Based on ambient noise records from two short-period dense seismic arrays deployed in the Sanshui Basin, South China, we obtained the high-resolution S-wave velocity images with lateral resolution of 0.04 degrees & times; 0.04 degrees within a 5.5 km depth range of the Sanshui Basin. Combined with spatial distributions of the Gekeng salt mine and mantle-derived hydrogen H2, the deep structure control mechanism and fundamental controls on subsurface resource formation are discussed. Our results show that the Gekeng salt mine buried at a depth of 1.2-1.5 km corresponds to a distinct low-velocity anomaly in the shallow layer (0.5-2.5 km), and that its low-density and high-porosity characteristics are consistent with the loose water-bearing property of the salt rock reservoir. Shallow earthquakes of ML4.4 and Ms3.4 that occurred in the salt mining area in 1997 and 2023, respectively, have sources located near the transition zone of high-low velocity anomalies. Based on these results, it is speculated that salt mining activities such as high-pressure water injection and mined-out area collapses may lead to the stress imbalance of secondary faults in the mining area, superimposing the main tectonic stress direction in the area, and potentially inducing medium to small magnitude earthquakes. By comparing our work with previous results about the transmission channel of the natural hydrogen H2, it is inferred that geothermal activity promotes hydrothermal fluid to rise along the fault, causing recrystallization of surrounding rock and hydrothermal diagenesis, and resulting in high-velocity anomalies of shear wave velocity in geothermal fields. This study reveals the accumulation mechanism of salt mine and natural hydrogen: salt mines are controlled by sedimentary environment and tectonic activities of fault-depression basins, while hydrogen enrichment depends on the rift-fault-hydrothermal coupling system, which provides helpful information for safe development of salt mines and carbon-free energy exploration.

The Bogda Mountains, located in the middle-eastern section of the northern Tian Shan, are the forefront of its growth and expansion toward the Junggar Basin. Since the late Cenozoic (similar to 30 Ma), intense activity along piedmont faults has driven the rapid uplift of the Bogda Mountains and shaped the fluvial landscape. In this study, we used the bedrock channel stream-power erosion model and topographic analysis tools to extract 61 watersheds within the Bogda Mountains. Geomorphological parameters including the hypsometric integral (HI) and normalized steepness index (k(sn)) were also calculated. Results indicate that the landscape of the Bogda Mountains is primarily controlled by three active faults. The Fukang fault is currently the most active, whereas the North Bogda fault has gradually weakened. The South Bogda fault may have experienced a period of tectonic reactivation. The analysis of chi and Gilbert metrics suggest respectively different results of drainage divide migration, indicating a tectonically controlled pattern of non-uniform uplift in the Bogda Mountains and the differential activity of the boundary faults. The drainage divide currently maintains a state of dynamic equilibrium. In this study, knickpoint response times were calculated through reconstructing paleo-channel profiles, concluding that the Bogda Mountains have undergone two significant tectonic uplift events at approximately 25-20 Ma and 5 Ma.

Fold-and-thrust belts typically develop in the frontal regions of compressive orogens and are characterized by significant fault offsets and fold deformation. Quantifying their geometry and kinematics is essential for understanding the fault behavior and mechanisms driving mountain uplift and propagation of shortening. This study analyzes a flight of five deformed fluvial terraces along the Tongziba River in the eastern Qilian Shan, northeastern Tibetan Plateau, utilizing high-resolution satellite imagery-derived digital elevation models and optically stimulated luminescence dating to elucidate the kinematics and slip rate of the Minle-Damaying fault. The fault-related folding analysis indicates that the Minle-Damaying fault has a listric geometry, with the fault dip decreasing from-40 degrees near the surface to 16 degrees-18 degrees at-1 km depth. Vertical uplift rates based on terrace uplift are 1.34 +/- 0.21 mm/ yr for terrace T5 and 1.29 +/- 0.27 mm/yr for T4, while shortening rates derived from balanced cross sections reach 1.94 +/- 0.25 mm/ yr and 1.87 +/- 0.36 mm/yr, respectively. These values exceed those estimated from near-field fault scarp measurements, indicating that localized scarp data may underestimate true deformation. The similarity of shortening rates along different segments of the North Qilian Shan fault supports the interpretation that this fault system plays a key role in ac commodating crustal shortening, uplift, and northward propagation of the Qilian Shan.

Abstract: The collision and compression between the Indian and Eurasian plates have resulted in intense crustal shortening and deformation in the Tian Shan since the Cenozoic, leading to its renewed uplift and making the Tian Shan one of the most intensely deformed intracontinental orogenic belts and seismically active regions in the world. Cenozoic deformation of the Tian Shan is characterized by north–south crustal shortening, which is mainly controlled by approximately E-W striking thrust faults, N-W striking dextral strike-slip faults, and N-E striking sinistral strike-slip faults. Concurrently, pronounced tectonic deformation occurred within the Tien Shan, forming a series of E-W trending intermontane basins, including the Turpan, Kumishi, Yanqi, and Yili basins. The Yanqi Basin, located in the southeastern Tian Shan, has experienced significant tectonic deformation due to the continuous uplift of the Tien Shan. Since the Late Quaternary, tectonic deformation has been mainly concentrated along the northern and southern margins of the basin. Two major active tectonic systems are developed along the northern margin, including the Yanqi Basin north-edge thrust fault and the piedmont thrust-fold belt. Along the southern margin, the Yanqi Basin south-edge thrust fault is developed, striking E-W and dipping southward, forming a complex thrust-fold belt. Within this fold belt on the southern margin of the basin, Quaternary geomorphic surfaces are well preserved and display fault scarps of variable heights. Multiple generations of alluvial fans are dissected along the fault scarps. In this study, high-resolution topographic data of faulted alluvial fan landforms along the southern margin thrust-fold belt were acquired using airborne LiDAR. Detailed geomorphic interpretation and quantitative analysis were conducted to identify multiple generations of landforms developed perpendicular to the fault strike. Based on comprehensive geomorphic interpretation and field investigations, deposits from different generations of alluvial fans were sampled for surface age determination. Furthermore, based on measurements of exposed strata and the construction of characteristic topographic profiles across the alluvial fans, we established the cross-sectional geometry and deformation model of the thrust fault-fold belt at the south-edge of the Yanqi Basin. By integrating the tri-shear fault-propagation fold model from fault-related fold theory, we constrain the shortening deformation characteristics of the thrust fault-fold belt. This allows us to estimate the shortening amount and shortening rate for the belt at the southern margin of the Yanqi Basin. Combined with analysis of surrounding fold deformation and fault slip rates, this work not only reveals the deep geometry and activity mechanism of the thrust fault at the south-edge of the Yanqi Basin but also provides constraints for understanding intracontinental deformation within the Southern Tian Shan.

The North Qilian Shan, located in the northeastern Tibetan Plateau, serves as a tectonic boundary zone both for active blocks and plateau expansion, and is characterized geomorphologically by intense shortening and uplift. To quantify the geomorphic expression of the outward expansion, we selected the Dongda River Watershed as the study area, divided it into three tectonic regions (A, B and C) to conduct quantitative geomorphological analyses. We then calculated the geomorphic indices—normalized channel steepness ( ksn ), slope, relief and hypsometric integral (HI)—for 212 sub‐basins in the Dongda River Watershed using TopoToolbox and the Topographic Analysis Kit (TAK). The distribution of parameters showed that the tectonic activity in the study area is Region A > Region C > Region B, which indicated that the North Qilian Shan exhibits geomorphic evidence of uneven tectonic uplift, reflecting differential tectonic activity along the North Qilian Shan fault zones during the Late Cenozoic. When combined with previously established tectonic evolution models for the North Qilian Shan, the results in this study suggest that tectonic activity here is driven both by the northward expansion of the plateau boundary and by stress transmission within block boundary zones.

To better constrain the paleoseismicity and assess the seismic hazard, we investigated the eastern segment of the Serteng Shan frontal fault along the northern margin of the Ordos Block. The Ordos Block in northern China has a stable interior but is surrounded by seismically active faults. Several historical earthquakes with magnitude >= M7 have ruptured along the northern boundary of the Ordos Block. Using excavated trenches, the eastern segment of the Serteng Shan frontal fault along the northern margin of the Ordos Block was investigated. Seven events were identified based on distinct geological markers, such as colluvial wedges. To constrain the timing of these events, 28 samples were collected and dated using the optically stimulated luminescence (OSL) method. The dating indicates show that all seven events occurred after similar to 90 ka, with the five most recent events occurring after 50 ka. Based on OxCal modeling results, the most recent event is inferred to have occurred at 7.0 +/- 1.1 ka. The penultimate and preceding events occurred at approximately 25.0 +/- 2.2 ka, 35.6 +/- 1.5 ka, 41.3 +/- 1.9 ka, and 46.2 +/- 2.4 ka, respectively. The minimum recurrence intervals are approximately 5 ka, or multiples thereof, resulting in longer intervals of up to similar to 20 ka. Combining the displacement of the T6 terrace and their corresponding ages, a uniform vertical slip rate of 0.15 +/- 0.02 mm/yr over the last 90 ka is estimated. The slip rates and recurrence intervals indicate that the eastern segment of the Serteng Shan fault experiences a low rate of surface-rupturing earthquakes. This behavior could be explained by the effect of unloading of a mega-paleolake in the Hetao Basin at similar to 50 ka. These results provide new constraints on long-term slip behavior and inform seismic hazard assessment.

[Objective]The early Cenozoic collision between the Indian and Eurasian plates triggered multi-stage uplift of the Tibetan Plateau,resulting in its remarkable landscapes and abundant mineral resources,while profoundly influencing climate,environment,and hazard evolution across Asia and beyond.The Tibetan Plateau and its surroundings have undergone intense tectonic activity and recurrent natural disasters,particularly earthquakes,which have significantly shaped its tectonic and geomorphic evolution.Seismic records indicate that more than half of the major earthquakes on the Chinese mainland and the surrounding regions occur within the plateau and its margins,controlled by the diverse types,scales,and distributions of active faults.[Methods]This study synthesizes decades of research on active faults and earthquake hazards across the Tibetan Plateau.It builds on the results of the Active Faults and Earthquake Hazards theme of the Second Tibetan Plateau Scientific Expedition and Research Program(STEP),which provided detailed documentation of major active fault zones.This study integrated current deformation fields,seismicity,and stress regimes to examine the seismotectonic settings associated with strong earthquakes across different regions of the plateau.Based on this analysis,the future seismic hazard potential of the plateau was further evaluated.[Conclusion]The image of active faults on the Tibetan Plateau indicates that different regions comprise fault systems with diverse scales,kinematics,and activity patterns.The tectonic settings associated with strong earthquakes have evolved through prolonged,multi-stage deformation,progressively establishing the present seismotectonic framework governing the nucleation and occurrence of large earthquakes.Current patterns of crustal deformation reveal northeastward deceleration with limited eastward extrusion of crustal blocks.Stress regimes,in contrast,are characterized by shear-extension in the interior and compression along the margins.Seismic hazard trends inferred from active tectonics and crustal deformation suggest a distinct segmented zonal pattern of strong earthquake activity,with plateau margins and fault-dense interiors representing the primary loci of future large earthquakes.Additionally,tectonic and geomorphic boundary zones demonstrate an increased likelihood for strong seismic events.

The growth and development of faults are driven by repetitive earthquakes, which accumulate displacement and extend rupture lengths. This process changes fault morphology, resulting in surface ruptures that are preserved in the geomorphology as displaced landforms. High-resolution geomorphic data enable the precise acquisition of these displaced landforms, facilitating detailed analysis of slip distributions along faults and offering quantitative constraints on the growth and rupture history of faults. In this study, an airborne light detection and ranging (LiDAR) system was employed to obtain 0.5-m resolution geomorphic data >500 m long on both sides of the Luoshan Fault on the northeastern Tibetan Plateau. By interpreting and distinguishing different geomorphic markers, we identified and measured 436 right-lateral offsets along the Luoshan Fault. Based on statistical analysis methods, we determined that there were six strong earthquakes within 10 m of the cumulative displacement along the Luoshan Fault. Except for the latest event, the other five strong events showed regular displacement increments of approximately 1.9 m, revealing a strong earthquake pattern of approximate characteristic slip. The different cumulative displacement distributions correspond to various stages of fault growth. The growth pattern of the Luoshan Fault evolves from fault tip propagation and linkage (Events 1-5) to a mode of growth with a constant fault length but increased cumulative displacement (Event 6). Based on the displacement distribution along the Luoshan Fault, the northern segment is more likely to experience earthquake events, with magnitudes ranging from Mw 6.84 to 7.12.

Numerous rural residential buildings exhibit inadequate seismic performance when subjected to blast-induced vibrations, which poses potential threats to their overall stability and structural integrity when in proximity to blasting project sites. The investigation conducted in conjunction with the Qianshi Mountain blasting operations along the Wenzhou segment of the Hangzhou–Wenzhou High-Speed Railway integrates household field surveys and empirical measurements to perform modal analysis of rural residential buildings through finite element simulation. Adhering to the principle of stratified arrangement and composite measurement point configuration, an effective and reasonable experimental observation framework was established. In this investigation, the seven-story rural residential building in adjacent villages was selected as the research object. Strong-motion seismographs were strategically positioned adjacent to frame columns on critical stories (ground, fourth, seventh, and top floors) within the observational system to acquire test data. Methodical signal processing techniques, including effective signal extraction, baseline correction, and schedule conversion, were employed to derive temporal dynamic characteristics for each story. Combined with the Fourier transform, the frequency–domain distribution patterns of different floors are subsequently obtained. Leveraging the structural dynamic theory, time–domain records were mathematically converted to establish the structure’s maximum response spectra under blast-induced loading conditions. Through the analysis of characteristic curves, including floor acceleration response spectra, dynamic amplification coefficients, and spectral ratios, the dynamic response patterns of rural residential buildings subjected to blast-induced vibrations have been elucidated. Following the normalization of peak acceleration and velocity parameters, the mechanisms underlying differential floor-specific dynamic responses were examined, and the layout principles of measurement points were subsequently formulated and summarized. These findings offer valuable insights for enhancing the seismic resilience and structural safety of rural residential buildings exposed to blast-induced vibrations, with implications for both theoretical advancements and practical engineering applications.

Strong earthquake activity along fault zones can lead to the displacement of geomorphic units such as gullies and terraces while preserving earthquake event data through changes in sedimentary records near faults. The quantitative analysis of these characteristics facilitates the reconstruction of significant earthquake activity history along the fault zone. Recent advancements in acquisition technology for high-precision and high-resolution topographic data have enabled more precise identification of displacements caused by fault activity, allowing for a quantitative assessment of the characteristics of strong earthquakes on faults. The 1920 Haiyuan earthquake, which occurred on the Haiyuan fault in the northeastern Tibetan Plateau, resulted in a surface rupture zone extending nearly 240 km. Although clear traces of surface rupture have been well preserved along the fault, debate regarding the maximum displacement is ongoing. In this study, we focused on two typical offset geomorphic sites along the middle segment of the Haiyuan fault that were previously identified as having experienced the maximum displacement during the Haiyuan earthquake. High-precision geomorphologic images of the two sites were obtained through unmanned aerial vehicle (UAV) surveys, which were combined with light detection and ranging (LiDAR) data along the fault zone. Our findings revealed that the maximum horizontal displacement of the Haiyuan earthquake at the Shikaguan site was approximately 5 m, whereas, at the Tangjiapo site, it was approximately 6 m. A cumulative offset probability distribution (COPD) analysis of high-density fault displacement measurements along the ruptures indicated that the smallest offset clusters on either side of the Ganyanchi Basin were 4.5 and 5.1 m long. This analysis further indicated that the average horizontal displacements of the Haiyuan earthquake were approximately 4–6 m. Further examination of multiple gullies and geomorphic unit displacements at the Shikatougou site, along with a detailed COPD analysis of dense displacement measurements within a specified range on both sides, demonstrated that the cumulative displacement within 30 m of this section of the Haiyuan fault exhibited at least five distinct displacement clusters. These dates may represent the results of five strong earthquake events in this fault segment over the past 10,000–13,000 years. The estimated magnitude, derived from the relationship between displacement and magnitude, ranged from Mw 7.4 to 7.6, with an uneven recurrence interval of approximately 2500–3200 years.

The active block theory was introduced into intracontinental earthquake research that strong continental earthquakes are controlled by the movement and deformation of active block. This theory is very important for understanding strong earthquake occurrence and related mechanisms far away from the plate boundaries, and also provides conceptual framework for short- and long-term prediction of strong earthquakes on the continents. The boundary zones of active blocks composed of different types of active structures is the potential risk areas where strong earthquakes occur, which have been proved by the occurrences of modern earthquakes in recent years. With respects to this correlation between the occurrence of strong earthquake among different active tectonics, a comprehensive study is needed to focus on the faults related to strong earthquake but also the associated active block. Here we summarized long-term strong earthquake activities in the boundary zones and characteristics of the active blocks, and provides more complete estimates on future risk areas around the Ordos block. The Ordos Block, situated in the central part of the mainland of China, represents a typical active block surrounded by diverse active tectonic zones. As one of the most significant seismically active regions in the mainland of China, the Ordos Block has experienced over 50 strong earthquakes with magnitudes (M) >= 6.5 according to historical records. Notably, the vicinity of the block has experienced over 5 large earthquakes with M >= 8. Due to the dynamic effect of the Tibetan Plateau and the Pacific Plate, the Ordos block has significant strong earthquake, leading to distinct fault systems with varying characteristics of movement, zoning, and segmentation along its boundary zones. In total, we recovered 180 strong earthquake events from the main fault zones around the Ordos active block and recovered the different structural zones in the boundary zones. Based on paleoearthquake and historical earthquake records, we reconstructed time series of strong earthquake occurrence in the past 15000 years. Our time series of seismic activities extended strong earthquake research from thousand-year to ten-thousand-year scale that enabled us to obtain better spatial and temporal image of strong earthquake activities from different tectonic areas around the Ordos active block. Our results showed that there are differential active and quiet periods in each zone of the block boundary, with varying clusters of strong earthquakes in the north, northeast, east and west boundaries, quiet periods varied from similar to 200 to 500 years in the past 15000 years. In the past 5000 years, the frequency of strong earthquake has been significantly increased in each boundary zone, indicating high risk of strong earthquake in these segments. Based on historical earthquake records and our latest images, we recognized 7 high risk areas in the boundary zone, namely, Wuhai-Linhe, Tongxin-Azouqi, Tianshui-Baoji, Yuncheng basin, Taiyuan basin, northeast Shanxi basin and Hohhot-Daihai basin around the Ordos active block.

Active fault zones are areas impacted by intense tectonic activity, where geohazards such as landslides occur and their distribution characteristics vary across segments. Using the Litang fault zone in the eastern Tibetan Plateau as an example, this study cataloged landslides within a 10 km range on both sides of the fault zone. The Litang fault zone was divided into four sections based on landform characteristics and the spatial distribution of active faults. A comprehensive analysis was conducted on the relationship between landslide distribution and topography, lithology, and active faults in different sections. Additionally, the study employed a random forest model to compare landslide susceptibility between the whole-region and its sub-regions. The results show that lithology and topography significantly influence the distribution of landslide types. The Upper Triassic sandstone, Slate exhibit more debris flows in areas with slopes ranging from 5 degrees to 35 degrees, while slopes >35 degrees in the Upper Triassic sandstone, Slate are prone to unstable slopes. Rock avalanche occur in Upper Triassic sandstone, Slate, and Quaternary sand and gravel. Active faults play a key role in control ling landslides distribution through distance, hanging wall, locked segment, and direction effects. The number of landslides is positively correlated with the activity of faults. Additionally, the dip angle and motion characteristics of faults have significant influence on the distribution of landslides. The results of landslide susceptibility evaluation show that sub-region models have higher accuracy than the whole-region model. This study provides a new method for exploring the spatial distribution of landslides and can provide scientific reference for reducing landslide disasters in active fault zones.

Fault zones along active tectonic block boundaries are a significant source of devastating continental earthquakes. Strong earthquakes produce disruptions of sediment and induce characteristic sediments near the fault, which serve as valuable sedimentary evidence for identifying and dating of paleoearthquakes. In this study, we aimed to reconstruct the earthquake history of the Qilian–Haiyuan fault zone in the northeastern Tibetan Plateau during the Holocene. We reanalyzed forty-four trenches and used the sedimentary sequences, event indicators, and age constraints to determine the earthquake history. Our analysis revealed the paleoearthquakes of 6 subsidiary faults of the Qilian–Haiyuan fault zone with accurate event ages and rupture extents. Based on the spatial and temporal distributions of strong earthquakes since 10 ka, we identified five earthquake clusters around the central-eastern Qilian–Haiyuan fault zone including seven rupture cascades where the earthquakes migrated gradually from east to west. The existing seismic gap reveals that the latest migration may not yet be complete and suggests a high probability of M ≥ 7 earthquakes occurring on the Jinqianghe fault, Maomaoshan fault, and the central part of the Lenglongling faults. We concluded that, in order to better understand earthquake cycles and seismic hazards, it is important to consider a fault zone as a whole, including multiple faults and their interaction on the earthquake triggering between nearby faults.

High-resolution topographic datasets are useful for revealing offset features of fault geomorphology and are thus important for reconstructing the evolution history of faults. The Riganpei Co fault, located in the central Tibetan Plateau, is an important active fault on the northern boundary of the Bangong-Nujiang suture zone. In this study, WorldView-2 stereo images were used to generate high-resolution topographic data in a 1 km range on both flanks of the middle section of the Riganpei Co fault. We interpreted the tectonic geomorphology along the fault, classified it into distinct units, and measured the horizontal displacement of each unit. Within approximately 70 km along the fault, we obtained 396 displacement measurements ranging from 0 to 60 m. Given the evident uneven distribution of displacement, the fault was divided into four segments. In each fault segment, the reconstructed slip distributions revealed a tendency of larger displacements in the center and smaller displacements toward the ends. The cumulative offset probability distribution (COPD) of displacements displays 4-5 offset clusters in the range of 0-30 m for each segment, suggesting that at least four large earthquakes ruptured this fault. The binned COPD demonstrated that there are differences in the displacement accumulation modes among these fault segments, where the middle segment follows a characteristic slip accumulation mode. Reconstructed cumulative slip profiles revealed a complex pattern of strong earthquake activities along the Riganpei Co fault.

Paleoseismic studies are critical for the assessment and prediction of large earthquakes (M >= 7). These studies involve excavating and analyzing evidence from surface-rupturing earthquakes. However, they often face limitations in spatiotemporal resolution. The Yuguang Graben, located in the northern Shanxi Grabens of North China, contains an abundance of Quaternary loess that can be utilized for extending paleoseismic records. Fine-grained deposits of loess contrast sharply with gravel deposits of the colluvial wedge, making the wedge shape apparent. To enhance our understanding of earthquake behavior in the Yuguang Graben, we excavated a trench on terrace T2 of the Songzhikou segment of the Yuguang Graben Fault (YGF). We used LiDAR to obtain a high-resolution orthophoto of the trench wall. Through OSL dating of colluvial wedges and loess, we identified at least four large paleoseismic events with a magnitude of M >= 7 that occurred along the YGF. These events took place at >77.6 +/- 5.1, 63.9 +/- 5.1, 51.0 +/- 4.3, and 37.3 +/- 0.3 kyr, respectively. Combined with previous paleoseismic studies, we identified seven paleoseismic events since the late Pleistocene. These findings reveal that earthquakes occurring on YGF follow a quasiperiodic pattern with an average recurrence interval of about 12 +/- 3 kyr. The elapsed time of the most recent earthquake near the recurrence interval suggests an increased risk of a large earthquake along the YGF. We also analyzed earthquake clusters generated by neighboring faults in the active northeastern boundary of the Ordos block. Our analysis indicated that fault interactions can affect the recurrence interval of earthquakes along single faults, while regional seismic activity tends to concentrate in time during a seismically active period. These observations underscore the importance of expanding paleoseismic records and exploring regional seismic hazards to gain a more comprehensive understanding of earthquakes.

Fault scarps preserve important information about past earthquakes on a fault, and thus can be applied to investigate the fault slip histories and rupture patterns. In this study, the morphology of fault scarps was used to constrain the paleoseismicity of the Wulashan Piedmont Fault located on the northern margin of the Ordos Block based on high-resolution LiDAR topography. We constructed the vertical displacement distribution of the fault through measuring the heights of a large number of scarp profiles extracted on different geomorphic surfaces along the fault. Through statistical analysis of the dense collection of vertical displacement dataset, a total of seven paleoseismic events were identified which followed a characteristic slip pattern with an average slip of ∼1.0 m. We further detected slope breaks in the fault scarp morphology to quantify the number of paleoearthquakes that occurred on the scarps, and discriminated at least five individual surface-breaking events. Both the number and slip of paleoearthquakes recognized from the morphology of fault scarps were in good agreement with previous paleoseismic trenching records. Based on the empirical scaling relationship between moment magnitude and rupture parameters, a moment magnitude of M w 6.7–7.5 was determined for the paleoearthquakes occurred on the fault. With the fault slip rate derived by previous studies, we estimated an average recurrence interval of 1.3–1.8 kyr for the paleoseismic events, which is very close to the elapsed time since the most recent earthquake, indicating a high potential seismic hazard on the Wulashan Piedmont Fault.

The Helan Shan is located on the front edge of the expanding Tibetan Plateau. However, how the topography here responds to this propagation and its precise time constraints remain unknown. Based on the response process of fluvial landforms and tectonic evolution, we conducted a quantitative landform analysis of the Helan Shan region. Here, the spatial distribution features of various geomorphic indices were coupled, demonstrating that the mountain is tilting toward the west and north. The steeper downstream and gentle upper reaches indicate that the fluvial landforms have experienced an accelerated incision event, which can be attributed to the tectonic activity along the East Helan Shan Fault. Furthermore, the response time of the tectonic knickpoints ranges from 0.1 to 1.4 Ma based on the paleochannel reconstruction method. Combined with previous studies on low temperature thermochronology and active tectonics, we proposed a tectonic transformation model where the Helan Shan shifted the tilting model from the southwest to the northwest, as induced by the northeast expansion of the Tibetan Plateau from 0.1 to 1.4 Ma.

The Qilian–Haiyuan fault zone in the northeastern Tibetan Plateau has been the source of strong earthquakes in the region. In its middle segment, the Jinqianghe fault is an important active fault within the Tianzhu seismic gap; however, little is known about its slip behavior. To present a new horizontal displacement distribution along this fault, we used WorldView‐2 stereo pairs and unmanned aerial vehicle‐based photogrammetry to construct digital elevation models to obtain a detailed tectono‐geomorphic interpretation and geomorphic offsets. The offset marker measurements yielded 135 geomorphic displacements and 8 offset clusters. Radiocarbon dating was used to establish the regional age sequence of the geomorphic units in offset fluvial terraces at four study sites. The displacements and ages linked the offset clusters with the geomorphic unit sequence; the Holocene strike‐slip rate of the Jinqianghe fault was estimated to 4.8–5.6 mm/a at ∼4–12 ka and 2.9–4.7 mm/a from ∼4 ka. Three recent earthquakes (with a recurrence interval of ∼1000 years) represent an active seismic period, revealing the potential seismic hazard along this fault because it has not ruptured in the last 1500 years.