ASSESSMENT OF ACTIVE TECTONICS FROM ALTERITES AND GEOMORPHIC INDICES IN A PART OF THE CRYSTALLOPHYLLIAN BASEMENT OF GRANDE KABYLIE (NORTHERN ALGERIA), IMPACT ON LANDSLIDES

Appraisal of active tectonics in Hindu Kush: Insights from DEM derived geomorphic indices and drainage analysis

The eastern Tell Atlas of Algeria is characterized by a complex neotectonic system including lateral strike-slips, and normal and reverse faults. The landscape of the Neogene basin of Mila-Constantine acquired its shape due to the perpetual action of tectonic activity, and erosion processes. Neo-tectonics in this basin have affected the geometry of the stream network and the contemporary landscape topography. Our methodology evaluates the active tectonics in this mountainous region by a combination of drainage network and geomorphic indices, namely, the basin-shape index (Bs), stream-length gradient (SL), hypsometric integral (HI), mountain front sinuosity (Smf), basin asymmetry factor (AF), and valley-floor ratio (Vf). The calculated values of the six measured geomorphic indices were used to differentiate the distribution of faults function as well as the relative tectonic activity in the study area. The obtained results from the GIS-based multi-criteria analysis of these indices consist of the index of active tectonics (IAT). Hence, we defined four hierarchic degrees of IAT, namely, very high (VH), high (H), moderate (M), and low (L). The relative active tectonics represents an obvious correlation between morpho-structural features, tectonic activities, and uplift rates. It selects the morphotectonic features and landforms that interpret the tectonic events in the study area. Our results prove that this approach discerns the most active regions related to the neo-tectonic action in the Rhumel-Smendou drainage basin. The combination of geomatics and field surveys highlights the cliffs which are still rising by using the drainage patterns, the landform model, and the mountain range shape.

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.

Special Region of Yogyakarta and Klaten district, Central Java is one of areas in Indonesia that is prone to earthquake caused by subduction in Indian Ocean and active fault in land. The earthquake sources from active fault probable from Opak and other faults located in Baturagung Mountain. Active faults controlling landform development in tectonically active regions, and it has significantly affected fluvial systems and mountain – front landscapes in the Baturagung Mountain. To assess tectonic activities in the area used quantitative analysis (morphometric). Morphometric analysis consists of 5 parameters geomorphic indices: drainage basin asymmetry (AF), hypsometric curve and integral (Hc and Hi), stream length gradient (SL) index, basin shape index (Bs), and mountain-front sinuosity (Smf). These indices were combined to yield the relative tectonic activity index (RTAI) using geographic information systems (GIS). The result found that RTAI in the study area are divided into three classes: Class 2 (high 0.6% of the watershed area (1.32 km2)); Class 3 (moderate 58.9% (122.1 km2)); and Class 4 (low 40.4% (83.75 km2)). All of morphometric analysis generally indicates this area more influenced by tectonics than erosion. The results are consistent with geomorphological observations.

Tectonic activity plays a vital role in achieving sustainable land management and hazard mitigation in seismically active regions. This study evaluates geomorphic indices derived from four digital elevation models (DEMs), including SRTM, Copernicus, FAB, and ALOS DEMs, to assess their influence on interpreting tectonic activity in the Wadi Araba basin. Six geomorphic indices, i.e. the hypsometric integral, stream length gradient, asymmetry factor, mountain front sinuosity, valley floor width to valley height ratio, and drainage basin shape, were integrated into a single Index of Relative Active Tectonics (IRAT) across sub-basins. The comparative analysis of multiple DEM datasets highlights the critical role of resolution and data quality in tectonic assessments, demonstrating that the ALOS DEM, with its 12.5-m resolution, captures finer details than 30-m DEMs (SRTM, Copernicus, and FAB DEMs), making it more suitable for applications requiring high sensitivity. However, the FAB DEM provides an acceptable balance of detail and smoothness, making it effective for general topographic studies while providing higher sensitivity than the SRTM and Copernicus DEMs. Hierarchical cluster analysis reveals the relationships between geomorphic indices and IRAT, emphasizing the impact of DEM selection on tectonic interpretation. The findings highlight the importance of using high-resolution DEM datasets in geomorphological and tectonic investigations to promote sustainability in the face of natural hazards.

Morphometric analysis is defined as the quantitative measurement of landscape shape. Morphometric studies of a watershed helps the researcher to compare different landform and calculate the geomorphic indices that may be useful for identifying a particular characteristic such as the level of neotectonic activity in a watershed. The present study has been carried out in Kakoi River Watershed which is a part of Lower Subansiri River Basin in Assam. The study area is geo-dynamically unstable region characterized by active faults, continuing crustal movements and complicated structural region which fall under the seismic zone V of India. In recent century, the Lower Suabsiri River Basin has gone tremendous morphological changes due to active tectonics activities. After the Assam Earthquake of 1950, some of the rivers like Subansiri and its tributaries Dirgha, Kadam and Kakoi suddenly changed their channels giving birth to new channels. The present study is to examine the neotectonic domains and the changes of river course. The geomorphic indices such as Hypsometric Integral (HI), Elongation ratio (Re), Asymmetry Factor (AF), Stream-length Gradient Index (SI), Mountain Front Sinuosity (Mfs), Basin shape index (Bs), Ratio of Valley floor width to Valley Height (Vf) and Channel sinuosity (S) etc. have been studied from remote sensing data. The results shows that the study area is under active tectonic area based on Vf (0.301), Rl (0.461), Bs (3.6), Sl (165.73) and other parameters such as S (1.38) and Mfs (2.02) indicated as moderate active tectonic region. Utilization of geospatial technology and remote sensing data in the present study becomes more reliable and helpful in analyzing, monitoring and understanding the landform changes in a watershed.

Assessment of relative active tectonic of the Khorramabad Basin using morphometric indices and fractal model analysis (Lorestan, north-west Zagros belt)

Morphotectonic analysis and GNSS observations for assessment of relative tectonic activity in Alaknanda basin of Garhwal Himalaya, India

The Tatra Mountains (Tatra Mts.) are the highest and most glacially reshaped mountain massif in the Carpathians. Previous studies suggested the tectonic uplift of this massif along the large sub-Tatric fault during Quaternary. The main goal of this paper is to characterise the tectonic activity in the Tatra Mts. using 6 geomorphic indices for 78 drainage basins: the stream-gradient index (SL), asymmetry factor (Af), basin shape ratio (Bs), hypsometric integral (Hi), valley floor width–valley height ratio (Vf), as well as mountain-front sinuosity (Smf). These parameters were combined in order to obtain the relative tectonic activity index (Iat) using GIS. The average of the six computed geomorphic indices was used to evaluate the distribution of relative tectonic activity in the study area. According to Iat values, four classes of different tectonic activity can be distinguished in the Tatra Mts.: class 1 of very high tectonic activity (0.7% of Tatra Mts.); class 2 of high activity (24.3%); class 3 of moderate activity (68.4%); and class 4 of low activity (6.6%). Our study confirmed previous suggestions about unequal uplift of different parts of the massif. Iat values show high tectonic activity along the Sub-Tatric fault, as well as in the northern part of the Belianskie Tatra. Distribution of Vf and Hi values correlate with extend of glaciers during Last Glacial Maximum. It seems that values of some geomorphic indices, such as Vf and HI, are strongly associated with glacial reshaping of the Tatra Mts. during the Pleistocene.

In this study, the morphotectonic features of the Yenişehir pull‐apart basin in Bursa in northwestern Turkey were analysed. The faults in the region are the most important structural elements that characterize the morphology of the Yenişehir pull‐apart basin. The aim of this study is to show the deformation effects of these active faults on the geomorphology with some basic morphometric indices. The morphotectonic features were evaluated using the hypsometric curve and hypsometric integral (Hi), drainage basin asymmetry (the asymmetry factor (AF) and the transverse topographic symmetry factor (T)), river length gradient index, mountain front sinuosity, and valley floor ratio. The morphometric indices that play an important role in the analysis of catchment areas are the Hi, AF, and T indices, which indicate tilting and erosion activities. According to the results of the hypsometric curve and hypsometric integral, the Yenişehir Basin is a young basin with a uniform topography as expected in an active pull‐apart basin formed by faulting in the Quaternary. The relative tectonic activity index (Iat) of the study area was calculated using the values of hypsometric integral, transverse topographic symmetry factor, asymmetry factor, mountain front sinuosity, valley floor ratio and stream length gradient index. The Iat values indicate the tectonic activity of the basin from Pliocene to Recent. Three different tectonic classes were identified in the study area. These are class 1 (high relative tectonic activity), class 2 (moderate relative tectonic activity), and class 3 (low relative tectonic activity). The Iat classification data show that the impact of tectonic activity on the geomorphology is lower in the Iat class 3 indices than in the others. The Iat data show high tectonic activity in the region where active faults of the North Anatolian Fault Zone southern branch are located.

ABSTRACTThe drainage pattern and the morphology of the piedmont zone of the Himalayas are clear indicators of the active orogenic belt of most recent origin formed by the collision of Indian and Eurasian plate. The foothills of the Himalayas in West Bengal are zones of active tectonics drained by the rivers belonging to the Brahmaputra system. The present study is conducted for the left bank tributaries and sub-tributaries of Tista which bear the imprint of active tectonics of the region as they lie in the zone of Himalayan Frontal Fault, the most active thrust belt of Himalayas. Data and subsequent field experiences which showed that the region is constantly acted upon by recent diastrophism. Various tectonic indices were calculated to evaluate the evidence of tectonism. This include hypsometric integral (HI), fractal dimension (FD), basin asymmetry factor (AF), basin shape index (Bs), stream-length gradient (SL), mountain front sinuosity (Smf) and valley-floor width to valley height ratio (Vf). The results of these indices are used to prepare an index of active tectonics with three classes which is represented in a map. Then the field evidences of deformed landscape are matched with the areas showing high tectonic index values.

Geomorphic and neo tectonic studies have been carried out for the first time in Mawar basin of the Kashmir valley. On the basis of field investigations and geomorphic data derived from toposheets and satellite imageries, with the help of Arc GIS (10.3) and Global Mapper (18) the relationship between morphology and tectonics has been investigated in Mawar basin, which lies to the northwest of Kashmir valley. The morphotectonic aspects like mountain front sinuosity (Smf), hypsometric integral (Hi), have been studied to relate the tectonic forces with erosive power and identify the areas where field investigations are required. The field interpretation indicates that the landforms of the area are structurally controlled and mainly consist of tectonic linear, parallel striking ridges and valleys. The course of Mawar is mostly controlled by the Mawar fault striking east–west and local structures present in the area. General morphometric parameters like assymetry factor (Af), transverse topography symmetry (T), stream length gradient (SL) and valley floor width to height ratio (Vf) have been computed to draw the conclusion of tectonic activity on the drainage. The Af and T suggest that the basin has shifted to the right side and the Mawar river has shifted to the left side when facing downstream. The SL values indicate that the river has fluctuations in gradient/knickpoints at 6.8, 10 and 18 km from the source. However the Vf values infer the basin has deeply incised V-shaped valleys. All the quantified geomorphic indices and their interrelationship with the geomorphology are useful in comparing different drainage basins in terms of tectonic character and are helpful in delineating the areas where more detailed works will be fruitful. The results of computed geomorphic indices, geomorphology and the structures present in the Karewas (Plio Pleistocene) deposits inferred that the basin has shown activity in Pleistocene period, suggesting the basin is tectonically active.

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.

Assessment of the geomorphic indices in relation to tectonics along selected sectors of Borpani River Basin, Assam using Cartosat DEM data

Karangsambung, located in Central Java, Indonesia has complex geological conditions of the tectonic evolution of Java Island due to the subduction process of the India-Australia plate with the Eurasian plate in the Cretaceous-Paleocene. The tectonic movements in the subduction zone have resulted in diverse geological structures and rock types and impact the morphological shape of the study area. The level of tectonic activity in the study area can be determined using a tectonic geomorphological approach. A digital elevation model and geographic information systems are used for geomorphic data processing. Geological data observations were also carried out in the form of river terraces. Seven geomorphic index parameters have been calculated to determine the youngest tectonic activity through the relative tectonic activity index (IAT) of the study area: the ratio of the valley floor width to the valley height, the drainage basin asymmetry, the river gradient-length index, the basin shape index, mountain front sinuosity, drainage density, and the hypsometric integral/hypsometric curve. The IAT score is divided into four classes which are class 1 (0%) very highly, class 2 (13%) highly, class 3 (56%) moderately, and class 4 (31%) low. The IAT shows that the research area is categorized as an active tectonic area so that the morphology formed is more influenced by tectonic activity than erosion. Geological data analysis on uplifted and deformed river terrace outcrops shows that the study area is affected by neotectonic activity.