Geomorphic Indices Research Articles

Morphotectonic Evolution of the Siwalik Hills between the Yamuna and the Markanda River Exits, NW Himalaya

ABSTRACT The Main Frontal Thrust (MFT) marks the present day active deformation front of the Himalaya and separates it from the Indo- Gangetic plains. The dynamic growth of the outermost Siwalik hills due to thrusting along the MFT has a direct influence on the drainages which collectively control the landform evolution of the region. In this study, the Siwalik hills (called as the Dhanaura range in the study area) between the Markanda and the Yamuna river exits in the NW Himalaya is investigated for its morphotectonic evolution using geomorphic indices, longitudinal river profiles, and topographic profiles. The results suggest presence of at least four structures that have merged to form the Dhanaura range. The first expression of the Siwalik hills was marked by the uplift of the surface due to a blind thrust in the northwestern part of the study area, followed by the growth of the Pataliyon anticline along a northeastern segment. The growth of the Dhanaura anticline occurred later by the merging of three MFT segments in the southern part of the study area. The Dhanaura anticline formed a barrier to the drainages arising from the initial northern topography, forcing them to get deflected. There also exists an unidentified structure to the north of the Dhanaura anticline as evident from the longitudinal river profiles, structural data, and drainage network of the area. Low mountain front sinuosity ratio, moderate hypsometric integral (HI) values and tilting of drainage basins in the study area suggest the structures are active.

Regional relative tectonic activity of structures in the Pampean flat slab segment of Argentina from 30 to 32°S

The Pampean flat slab segment of the Central Andes in Argentina is a broad, active deformation zone subject to both plate boundary-related and intraplate deformation. To the west, plate boundary-related deformation is dominated by thin-skinned fold-and-thrusts of the Precordillera, while to the east, intraplate deformation involves thick-skinned reverse faults of the Sierras Pampeanas. GPS data and absolute dating of displaced geomorphic features suggest that most of the active permanent deformation occurs between these two regions at the Andean orogenic front and that there is a west-to-east trend of decreasing shortening rates. However, GPS stations and sites with geomorphic slip rate measurements are currently too sparse and cover too short a time period to make reliable inferences about the longer-term distribution and relative rates of deformation. Mountain range-scale geomorphic indices, on the other hand, reflect tectonic activity since at least the Pleistocene. In this study, we measured geomorphic indices (hypsometric integral and curves, basin elongation ratio, basin volume-to-area-ratio, valley floor width-to-height ratio, mountain front sinuosity, and normalized steepness indices of rivers) from 10 different N-S striking, range-bounding faults that span both the Precordillera and Sierras Pampeanas regions from west to east. We use these data to assess the regional relative tectonic activity of major Quaternary deformation features in the Pampean segment of the Central Andes. Even when variations in climate and geology are considered, mean values for each geomorphic index suggests uplift rates for the 10 mountain-range bounding faults display local trends that are closely associated with the structural style and tectonic evolution of these structures. Although vertical uplift rates vary little, horizontal shortening rates are higher for the Precordillera fold-and-thrusts in the west than the thick-skinned reverse faults of the Sierras Pampeanas in the east, due to shallower fault dips for Precordilleran structures. The similarity with decadal slip rate gradients from GPS studies could possibly indicate that the stress-field has been constant since at least the Pleistocene, but further slip rate studies over broader time intervals in the late Quaternary are necessary to confirm this. Variations observed in relative uplift rates along each fault point to sites that warrant further detailed study of slip rates and evaluation of associated seismic hazards.

Tectonic geomorphology of the Serranía de San Lucas (Central Cordillera): Regional implications for active tectonics and drainage rearrangement in the Northern Andes

We explore the structural and geomorphological evidence for recent tectonic activity in the Serranía de San Lucas (San Lucas Range, SLR), the northern segment of the Central Cordillera in the Colombian Northern Andes. A morphostructural and geomorphological analysis was carried out in this isolated range using several topographic metrics like the local relief, slope variability, hypsometric integral, swath profiles, normalised concavity steepness (ksn), drainage basin shape index (Bs), asymmetry factor (AF), mountain front sinuosity (Smf) and the ratio of valley floor width to valley floor height (Vf).After remote sensing and geological analysis of the structural pattern, we propose that the SLR represents a horse-tail termination of the Palestina Fault that seems to have reactivated in the Miocene / Pliocene in a transpressive stress state, during the Andean Orogeny. Based on this structural model and the geomorphic indices, we divided the SLR into two regional domains: the Simití domain in the east and the Palestina domain in the west. The Simití domain is dominated by NE-SW striking structures with a right-lateral kinematic, whereas the Palestina domain is controlled by the N–S right-lateral Palestina Fault, which is the predominant structure in the SLR. We demonstrate that recent tectonic activity and higher uplift rates have been preferably constrained to the Simití domain, to the north of the Simití – San Blas faults, along the NE-SW striking faults. In this area, low Smf and Vf values suggest an active mountain front bounded by the reverse Morales Fault and Quaternary uplift rates between 0.05 and 0.5mm/yr. On the other hand, the Quaternary tectonic activity in the Palestina domain was concentrated in the northern portion, where climate has also played a significant role in controlling denudation rates and landscape evolution.The variable uplift pattern between both domains has induced along-strike changes in divide mobility and timing of drainage reorganisation within the SLR. Discrete capture events forced a west-southwest migration of the eastern side towards the western side of the SLR. The concentrated highest tectonic activity in the Simití domain progressively modified the topographic conditions and triggered the divide migration event.Our findings provide new and valuable information on the active tectonics and Neogene to Quaternary landscape evolution in this poorly studied area in the Northern Andes.

Tectonic uplift of the northern Qinling Mountains (Central China) during the late Cenozoic: Evidence from DEM-based geomorphological analysis

The Qinling Mountains, which stretch from east to west in Central China, represent an important geological and geographical boundary between North China and South China. Because of the northeastward growth of the Tibetan Plateau since the late Cenozoic, the northern Qinling Mountains have been strongly reactivated and uplifted. To investigate the landscape response to the tectonic uplift, the geomorphic indices of the northern Qinling Mountains, including the hypsometry, mathematical function of the longitudinal profile, channel longitudinal profile, and steepness index were analyzed. The topographic analysis reveals that the landscape evolution of the Heihe River Basin is in a transient state. The upstream of the Heihe River Basin has undergone a long period of erosion and represents relict landscape. In contrast, the downstream represents adjusting landscape, which formed by river incision in response to the rapid uplift of the northern Qinling Mountains. This is a result of the extension of the Weihe Graben, which has formed due to the northeastward growth of the Tibetan Plateau during the late Cenozoic. The spatial distribution of the geomorphic indices reveals that the NE striking Taibai Fault has experienced strong tectonic activity since the late Cenozoic and is a secondary fault that accelerated the uplift rate of the northern Qinling Mountains. The tectonic stress due to the northeastward growth of the Tibetan Plateau has been transmitted to the northern Qinling Mountains along the Taibai Fault. Therefore, we proposed that the uplift of the northern Qinling Mountains is due to the combined effects of the Weihe Graben extension and Taibai Fault activity, forming the highest peak (Taibai Mountain) of the northern Qinling Mountains near the intersection of the Qinling Piedmont Fault and Taibai Fault.

Transient basin as indicator of tectonic expressions in bedrock landscape: Approach based on MATLAB geomorphic tool (Transient-profiler)

The tectonic and erosional processes sculpture the Earth's surface, producing a landscape that preserves the evolutionary history of rock uplift and incision. The bedrock channels act as an efficient gradation agent where the river profile adjusts to changing tectonic, climatic, or topological (e.g., river capture) boundary conditions, and develops a transient basin. A suite of slope-break knickpoints at comparable elevations in the channel profiles of the transient basin act as important markers. We developed a set of comprehensive and interactive MATLAB tools, called a Transient-profiler, to extract the geomorphic indices from the digital elevation model for a basin characterization and landscape evolution period. The paleo-channel reconstruction from the relict reach in the three studied transient drainage basins (Palar, Umiam, and Dibang) suggest a varying surface uplift from 514, 1246, and 1981 m with a respective relief gain of 158%, 230%, and 95%, respectively. We found that the horizontal knickpoint retreat rate is faster in the Himalayan thrust system as compared to the Shillong pop-up system, whereas the vertical knickpoint retreat rate is faster in the latter.

Tectonics controls on fluvial landscapes and drainage development in the westernmost part of Switzerland: Insights from DEM-derived geomorphic indices

This work focuses particularly on the geomorphological evidence for the tectonic controls on the development of the present-day fluvial landscapes in the westernmost part of Switzerland. The tectonic deformation was evaluated on the basis of a combined analysis of several classical geomorphic indices (hypsometric curves and integrals, transverse topographic symmetry index, and channel's bottom gradients) through high-precision DEM processing. A new optimization strategy was applied for defining geomorphic anomalies related to tectonic activity along the channels of three rivers, based on a combined investigation of topographic swath, longitudinal profiles, geological and geophysical observations. The results show that the abnormally high values of hypsometric integral are spatially occurred on the hanging walls of thrust faults, while abnormally low ones are spatially observed in the same locations of paleo-ice stream pathways. Observations obtained from transverse topographic symmetry index display asymmetries in the most of the studied drainage basins with a predominant SE direction of lateral migration. This direction is in agreement with the dominant dip-direction of the bedding planes within the study area. Abnormal changes in the channel's bottom gradients, which almost coincide in space with pronounced change in the depth of the subsurface geologic layers and in the geophysical properties, are marked by distinct topographic relief in areas where rivers flow above blind and emergent faults. Our analysis not only confirms that there is a significant tectonic control on the evolution of drainage systems, but also revealed a possible evidence for the reactivation of some inherited faults.

Fethiye Burdur Fay Zonu’nun Kuzeydoğu Kesiminin (Burdur-Güneybatı Anadolu) Göreceli Tektonik Aktivitesinin Jeomorfik İndislerle İncelenmesi

This study aims to investigate the tectonic activity with geomorphological indices within Burdur and Yarışlı Basins in the south of Burdur. The study area consists of Jurassic– Cretaceous ophiolitic melange, Late Triassic-Early Jurassic recrystallized limestone, Late Miocene – Early Pliocene marl and clayed limestone and Late Pliocene – Early Pleistocene alluvial fan deposit. The study area covers the NE section of the Fethiye - Burdur Fault Zone (FBFZ). The FBFZ, which caused many earthquakes in historical and instrumental periods, is represented by NE-SW trending Burdur, Karakent, Karacaören faults and NW-SE trending Karaçal fault. In addition there are many small scale faults in the area. In order to determine the tectonic activity of the region, some geomorphological indices such as Mountain-Front Sinuosity (Smf), Ratio of Valley-Floor Width to Valley Height (Vf), Normalized Stream Length – Gradient Index (SLK), Asymmetry Factor (AF), Topographic Symmetry Factor (T), and Index of relative active tectonics (Iat) were calculated. The obtained data were compared with the field observations. According to the results, Smf ranges between 1.03-1.66, average Vf ranges between 0.28-10.85, average SLK ranges between 1.84-7.95 and T ranges between 0-0.6. The AF value of Burdur Basin is 60,14 whereas the Iat values of sub-areas cover Class-2 and Class-3. Geomorphic indices, confirming the other geological findings, show that the study area has moderate to high level tectonic activity.

Assessment of active tectonics from geomorphic indices and morphometric parameters in part of Ganga basin

Ganga river basins exposed to active erosional and deformational processes. The recurrence of landslides, floods, and seismic activities makes it more susceptible to deformational activities. The tectonic analysis using geomorphic indices and morphometric parameters will help in determining the hazard-prone area of the river basin. Geomorphic indices and morphometric parameters are calculated to investigate the role of neotectonic activities, as it acts as a controlling factor in the development of landforms in the tectonically active terrains. Neotectonic activities influence the terrain topography, which significantly affects the drainage system and geomorphological setup of the area. In this study, the assessment of active tectonics of study area was determined using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) based on Geomorphic Indices (Stream Length Gradient index, Hypsometric integral, Asymmetry factor, Basin shape, Valley floor width to Valley height ratio, Mountain front sinuosity index) cumulatively with Linear, Areal and Relief morphometric parameters on 27 delineated basins of the study area. The combined classification of Relative Tectonic Activity Index (Iat) and morphometric parameters of 27 basins categorized all the zones into four different classes: Class 1 - Very High ( 2.21; 299 km2). The basins with tectonic activities have a consistent relationship with structural disturbances, basin geometry, and field studies. The tectonically active zonation of a part of Ganga basin using geomorphic indices and morphometric parameters suggest that it has significant influence of neotectonic activities in a part of Ganga basin.

Comparative Evaluation of Active Tectonics in Parts of the Frontal Region of NW Himalaya, India by Geomorphic Analysis and Geophysical Investigation

The Himalayan Frontal Thrust (HFT) is the southern-most boundary of Himalayan mountain belt. It represents a zone of active deformation between the sub-Himalaya and Indo-Gangetic alluvial plain. Morphometric analysis of five sixth order drainage basins along the HFT has been carried out for evaluating relative tectonic activity of the region. Based on the combination of various geomorphic indices such as drainage basin spatial asymmetry, drainage gradient, drainage cross profile and mountain front sinuosity indices, the relative tectonic activity in and around the test site drainage basins was evaluated. Where all the indices are not in agreement, the relative importance of the geomorphic indices was considered to evaluate relative tectonic activity which was then compared with the abundance of drainage anomalies and previously reported active tectonic features (including active faults and fractures). Finally, the results were corroborated with the spatial frequency distribution pattern of previous seismicity (>2.5 Mw). Geophysical investigation by multi-frequency, bi-static ground penetrating radar (GPR), conducted at selective locations in the piedmont-alluvial region of Solani and Markanda drainage basins, supports active deformation of sub-surface sediment layers. Well-defined offset and warping of near-surface sediment layers indicating the presence of active fault and deformation of sediment layers were observed in 40 MHz and 100 MHz radargrams near Biharigarh and Mujahidpur villages in Solani drainage basin (Uttarakhand and U.P.) and near Toka village in Markanda drainage basin (H.P.).

Geomorphic response of the river basin drainage in seismically active regions of India

Over the last few decades, the Indian subcontinent is gradually drifting towards northeast at a rate of 10 mm/year, which is an indication that the areas are actively deforming. Such a gradual rate of drift is expected to bring modifications and changes in the topography, which can be quantified with the help of geomorphic parameters. The current study examines the geomorphological changes in the seismically active areas of different geotectonic provinces of India, i.e., Northeast India and Bhuj region. The geomorphological changes have been estimated with the help of remote sensing and geographical information system modeling by calculating the geomorphic parameters. A total of 39 drainage basins were extracted from both the study areas using Aster GDEM data of 30 m resolution. Geomorphic indices such as stream order, stream length, bifurcation ratio, form factor, asymmetry factor and hypsometric integral were calculated for each drainage basin of the study regions. The geomorphic parameters reveal that the study areas are dendritic in character, even though having different geological formations, both study regions express similar lithological characteristics. With no strong control of structural elements, both study areas seem to be characterized by relatively high permeability and with relatively gentle slope. The extent of the carving of topography reveals that the drainage development and morphologic evolution of both areas have practically reached Late Mature and Old stage of terrain development. Even though the two study areas represent different seismotectonic provinces, it is observed that geomorphologically they are gradually approaching the stage of peneplanation.

Active bidirectional tectonic-tilting in a part of the Almora Klippe, Kumaun Lesser Himalaya, India: Insights from statistical analyses of geomorphic indices

The NW-SE trending, synformal Almora Klippe in central Kumaun Lesser Himalaya is actively uplifting along the basal thrust, which is known as North Almora Thrust (NAT) and South Almora Thrust (SAT) along the northern and southern flanks, respectively. Geomorphic indices of ‘Basin Asymmetry Factor (AF)’ and ‘Transverse Topography Factor (T)’ of 77 drainage basins of third-order streams developed on this tectonic block have been computed to decipher active tilt-block tectonics of a part of this vast klippe. Statistical analyses of the basins' geomorphic indices revealed differential, gentle to steep, bidirectional tilting of the Almora Klippe vis-à-vis lent insight into correct perspective which these must be used for such studies. The tectonic block of Almora Klippe is partitioned into two minor tectonic blocks along the hinge of the synform. Differential movements along the basal thrust of the klippe have caused westward down-tilting of the northern fold flank (‘AF’ having χ2 value of 7.556 for 4 azimuth classes at 90% confidence level, and ‘T’ having vector mean (θ¯v) of 260° and vector magnitude (r) of 0.25 at p-value of 0.1154), and eastward down-tilting of the southern fold flank (‘AF’ having χ2 value of 13.73 for 4 azimuth classes at 90% confidence level, and ‘T’ having vector mean (θ¯v) of 56° and vector magnitude (r) of 0.26 at p-value of 0.0585). The westward down-tilting of the northern fold flank is due to its faster uplift in the east, along the NAT. Similarly, the eastward down-tilting of the southern fold flank is due to its faster uplift in the west, along the SAT.

Morphometric evidences of recent tectonic deformation along the southeastern margin of the Hyblean Plateau (SE-Sicily, Italy)

The present work focuses on the tectonic characterization of the southeastern portion of the Hyblean Plateau (SE-Sicily, Italy). Along the southeastern margin of this raised crustal block, a clear recent antiformal deformation, coupled with diffuse landscape rejuvenation, affects the summit surface. Many studies, using merely qualitative geomorphological approach, refer the recent morphotectonic evolution of this region to motion along an active border fault, located at the base of the well-developed, arc-shaped Avola mountain front. This paper provides new insights resulting from the morphometric analysis across the Avola region, in order to detail on the relationships between the landscape geomorphic unsteadiness and the long-term tectonic deformation. We perform both drainage system and relief investigations, consisting of the exploration of different geomorphic indices (e.g. hypsometric integral, topographic relief and dissection, SL index, ksn), long-profile analysis, marine terraces age model definition, field-based geomorphological and structural surveys. The results and the spatial distribution of morphometric indexes evidence the occurrence of two incipient NNE trending en-échelon fault segments, here named Cassibile-Noto Fault, responsible for the relief building along the southeastern border of the Hyblean Plateau. The northern fault segment directly controls the northern portion of the Avola mountain front, whereas the southern segment diverges from the main scarp, cutting through the low-standing areas of the coastal plain. In addition, the centrifugal arrangement of fluvial captures and the half-elliptical envelope of the downstream projections of coeval paleo-long profiles, as well as the distribution of Pleistocene marine terraces, well evidence the long-term WNW-ESE-trending low-amplitude bow-shaped deformation affecting the footwall of the Cassibile-Noto normal fault. We relate this convex-upward trend to the Late Pleistocene (<125 ka) tectonic deformation cumulated, at rate of ~0.80 ± 0.05 mm/a, along the active fault. This incipient tectonic structure represents an extensional tectonic boundary that accommodates, together with the Ispica Fault, the active NW-ward motion of the entire eastern sector of the Hyblean Plateau. Overall, the proposed updating of the tectonic setting of the study area, framed in the regional geodynamic picture of the eastern Sicily, would contribute to define a more suitable geological risk assessment of the region.

Landscape expressions of tectonics in the Zagros fold-and-thrust belt

This study uses geomorphic indices, including normalized channel steepness index (ksn), integrated relief and hypsometric index (HI), to investigate how landscape responds to tectonic and climatic drivers in the Zagros fold-and-thrust belt, and show how geomorphology can be a sensitive indicator of tectonic processes. There is a broad association of relatively high ksn values (>50 m0.9) with the upper elevation limit for seismogenic thrusting, which occurs regionally at the 1250 m topographic contour. Higher ksn values occur beyond this seismicity cut-off in the Bakhtyari Culmination, but are rare in the Fars region. We measured HI values for 17,380 third order river basins across the Zagros. In many areas the low/high HI transition (0.3) is typically at the elevation limit of seismogenic thrusting. There are two important exceptions. In the Dezful Embayment/Bakhtyari Culmination the low/high HI transition lies at higher elevations than the thrust seismicity cut-off. In the Fars region, the HI transition lies at lower elevations than the seismicity cut-off. We explain these differences by the different climates of the two areas: wetter conditions and vigorous drainage systems in the Dezful/Bakhtyari region retard orogenic plateau growth; drier climate and low power rivers in the Fars region promote plateau growth. Orographic precipitation may itself have a tectonic control; regional basement strength variations have caused intense thrusting and high relief in the Bakhtyari Culmination. Integrated relief of five across-strike Zagros topographic swath profiles is in the range 2.2–2.8 108 m2. We argue that this consistency within ~25% relates to the comparable strain rates across different sectors of the Zagros, regardless of local structural, drainage network or climatic variations.

Drainage Pattern and its Bearing on Relative Active Tectonics of a Region: A Study in the Son Valley, Central India

ABSTRACT The paper emphasis the participation of different geomorphic parameters related to various characteristics of drainage in evaluation of active tectonics of an area. For the purpose, the morphotectonic evaluations of the Son valley, central India have been carried by involving various drainage related geomorphic indices viz., stream-gradient index (SL), hypsometric integral (HI), drainage basin asymmetry (AF), valley floor height and width ratio (Vf), transverse topographic symmetry factor (T), mountain front sinuosity (Smf), drainage basin shape (BS) and sinuosity index (SI) and relative rock strength (RRS) for classification of relative index of active tectonics (RIAT) in geographic information systems (GIS) environment to understand the role of active tectonics in geomorphologic evolution of the studied region. The established RIAT classes through field validations categorize the valley into four zones such as class 1- low activity ( RIAT &amp;lt; 2.7); class 2-moderate activity ( RIAT =2.7 &amp;lt; 2.99); class 3- high activity (RIAT=2.99 &amp;lt; 3.29); and class 4-very high activity (RIAT&amp;gt;3.29). The sub-dendritic, rectilinear and parallel linear drainage styles in RIAT classified basin reveal the traverse of a network of seventeen faults in association with two major faults namely Son-Narmada-North Fault (SNNF) and Son-Narmada South Fault (SNSF) in variable associations of rocks and multiple types of structural elements present in the Son valley. The signature of vertical upliftments may indicate the instability tectonic activities along the identified network of faults associated with SNNF and SNSF. Hence, the study suggests variable tectonically activeness of area in the Son valley.

Relative timing of uplift along the Zagros Mountain Front Flexure (Kurdistan Region of Iraq): Constrained by geomorphic indices and landscape evolution modeling

Abstract. The Mountain Front Flexure marks a dominant topographic step in the frontal part of the Zagros Fold–Thrust Belt. It is characterized by numerous active anticlines atop of a basement fault. So far, little is known about the relative activity of the anticlines, about their evolution, or about how crustal deformation migrates over time. We assessed the relative landscape maturity of three along-strike anticlines (from SE to NW: Harir, Perat, and Akre) located on the hanging wall of the Mountain Front Flexure in the Kurdistan Region of Iraq to identify the most active structures and to gain insights into the evolution of the fold–thrust belt. Landscape maturity was evaluated using geomorphic indices such as hypsometric curves, hypsometric integral, surface roughness, and surface index. Subsequently, numerical landscape evolution models were run to estimate the relative time difference between the onset of growth of the anticlines, using the present-day topography of the Harir Anticline as a base model. A stream power equation was used to introduce fluvial erosion, and a hillslope diffusion equation was applied to account for colluvial sediment transport. For different time steps of model evolution, we calculated the geomorphic indices generated from the base model. While Akre Anticline shows deeply incised valleys and advanced erosion, Harir and Perat anticlines have relatively smoother surfaces and are supposedly younger than the Akre Anticline. The landscape maturity level decreases from NW to SE. A comparison of the geomorphic indices of the model output to those of the present-day topography of Perat and Akre anticlines revealed that it would take the Harir Anticline about 80–100 and 160–200 kyr to reach the maturity level of the Perat and Akre anticlines, respectively, assuming erosion under constant conditions and constant rock uplift rates along the three anticlines. Since the factors controlling geomorphology (lithology, structural setting, and climate) are similar for all three anticlines, and under the assumption of constant growth and erosion conditions, we infer that uplift of the Akre Anticline started 160–200 kyr before that of the Harir Anticline, with the Perat Anticline showing an intermediate age. A NW-ward propagation of the Harir Anticline itself implies that the uplift has been independent within different segments. Our method of estimating the relative age difference can be applied to many other anticlines in the Mountain Front Flexure region to construct a model of temporal evolution of this belt.

Divide migration in response to asymmetric uplift: Insights from the Wula Shan horst, North China

Drainage divides play significant roles in shaping landscapes. Nevertheless, they are not static through space and time. Previous numerical models have demonstrated divide motions in response to asymmetric tectonic uplift. However, natural examples that have nicely recorded these processes and hence could verify the results of numerical simulations are still lacking. In this contribution, we integrate the results of digital elevation models (DEMs)-based morphotectonic analysis with the tectonic landforms observed during field surveys to investigate the status of topography and probable drainage evolution history of the Wula Shan (Shan means ‘Mountain(s)’ in Chinese), a roughly west-east trending horst block bounded by normal faults in the Hetao Graben, North China. The results demonstrate that the differences of obtained geomorphic indices are significant between the southern and northern drainage basins; higher hypsometric integral (HI) and normalized channel steepness (ksn) values, and lower ratios of valley floor width to valley height (VF) indicate higher tectonic uplift rate at the southern flank. The main divide of the Wula Shan had migrated northward, which was probably caused by the decrease of asymmetry in vertical uplift associated with the margin faults. We suggest the results of this study may shed new light on divide mobility as well as landscape evolution in actively extending regions.

Geomorphic evidence for northeastward expansion of the eastern Qilian Shan, northeastern Tibetan Plateau

The eastern Qilian Shan is a tectonically-active region consisting of a series of faults with bounded intermountain basins and is located within the transition zone between the mainland Tibetan Plateau and the Alax Block. Active deformation affecting the topography in this region can be quantified based on geomorphic indices. Therefore, we applied the geomorphic indices (hypsometry and stream-power incision model) to evaluate the tectonic deformation pattern of the eastern Qilian Shan. Hypsometric curves and S-A plots of the selected seven rivers were determined. HI values of every single sub-basins were also calculated. The results show that the local topographic evolution of the eastern Qilian Shan is in pre-steady state and will soon reach its equilibrium state. According to the analysis of regional climate condition (e.g., rainfall and glaciers distribution) and fault characteristics, it is suggested that abundant glacial snowmelt water sustains fluvial incision, and tectonic deformation from sustained northeastward expansion of the Tibetan Plateau is the main reason for the landscape growth. Combining the research of the deep electric structure beneath the Gulang Boundary Zone, we claimed that the eastern Qilian Shan (even the northeastern Tibet) has been growing and expanding northeastward since the middle Miocene, and its leading edge now is the Hexibao-Sidaoshan Fault. On the premise of synthetically considering the western and middle parts of the Qilian Shan, it is suggested that the Hexibao-Sidaoshan Fault area will rise into a mountain in 1–2 Ma.

Assessment of the Tectonic Activity in Northwestern Part of the Zagros Mountains, Northeastern Iraq by Using Geomorphic Indices

The Tectonic Activity of regions with active tectonics can be assessed by using of the geomorphic indices. Six Geomorphic indices including stream-gradient index (SL), drainage basin asymmetry (Af), drainage basin shape (Bs), hypsometric integral (Hi), valley floor width-valley height ratio (Vf), and mountain-front sinuosity (Smf) were calculated using GIS technique in Kifri Chai Basin; northeast Iraq, which belongs to the Western Zagros Mountain. The basin was divided into eighteen sub-basins depending on the 4th, 5th and 6th stream orders of the drainage within Kirfi Basin. It was found that the SL, Af, Bs, Hi, Vf, and Smf (J) values are uniform and exhibit almost the same classes. However, few exceptions occur, especially in Bs values, but the exceptional values do not influence significantly on the acquired results, in each of the eighteen sub-basin. From these indices the relative active tectonics index value (Iat) was determined. The results of average Iat values (2.35) showed that the tectonic activity in the whole basin is Moderate. Moreover, an attempt was carried out to compare the regional Neotectonic activity with the relative tectonic activity in the basin. The results showed that there is a positive relation between the two comparatives; especially the subsidence amount and scored relative tectonic activity.

Evaluation of relative tectonic activity along the Priene-Sazlı Fault (Söke Basin, southwest Anatolia): Insights from geomorphic indices and drainage analysis

The West Anatolia Extensional Zone, which has a width of about 300 km, is located within the Alpine-Himalayan belt and is one of the regions with intense seismic activity in the world. The most important geomorphological structures in this area are three main graben structures resulting from regional N-S extension since the Early Miocene. These structures are the E-W trending Buyuk Menderes, Kucuk Menderes, and Gediz grabens. Soke Basin is located at the SW end of the Buyuk Menderes graben. The lineaments which control the NW of Soke Basin have a length of approximately 40 km and have been defined as the Priene-Sazli Fault (PSF). The PSF is seismically active, and the last large earthquake (the Soke-Balat earthquake; Ms: 6.8) was produced on July 16th of 1955. The ancient city of Priene, which was located in the study area, suffered from destructive earthquakes (in the 4th century and 2nd century BC, in the 2nd century AD, during the Byzantine period and after the 12th century BC). This study aims to reveal the effect of the PSF on the morphotectonic evolution of the region and the relative tectonic activity of the fault. To this end, it was the first time the stream length gradient index (SL: 130–1303), mountain-front sinuosity (Smf: 1.15–1.96), valley floor height and valley width ratio (Vf: 0.27–1.66), drainage basin asymmetry (AF: 0.15–0.76), hypsometric curve (HC) and hypsometric integral (HI: 0.22–0.86) and basin shape index (Bs: 1.04–5.75) along the mountain front that is formed by the PSF. Using a combination of the mountain-front sinuosity (Smf), valley floor height and valley width ratio (Vf), it is found that the uplift ratio in the region is not less than 0.05 mm/yr and the relative tectonic activity of PSF is high. According to the relative tectonic activity index (Iat) obtained from geomorphic indices, the southwest part of the PSF is relatively more active than the northeast part. As a result, I posit that the PSF has the potential to produce earthquakes in the future similarly to those that were produced in the past, and that the most destructive earthquakes will likely occur on the southwest segments of the fault according to geomorphic indices.

Investigating the causes of groundwater leakage in Nahabad Mamsan plain using geomorphic indices based on geo Dualiteh theory

Investigating the causes of groundwater leakage in Nahabad Mamsan plain using geomorphic indices based on geo Dualiteh theory