Morphotectonic Features Research Articles

The Central Mindoro Fault: An Active Sinistral Fault Within the Translational Boundary Between the Palawan Microcontinental Block and the Philippine Mobile Belt

The NNW-trending Central Mindoro Fault (CMF) is an active oblique left-lateral strike-slip fault as determined from offset morphotectonic features such as spurs and streams. Mapping of the trace and determination of the sinistral strike-slip sense of motion of the CMF is essential not only to the assessment of hazards but also to providing a clearer perspective of its role in accommodating deformation resulting from the NW relative motion between the Philippine Sea Plate and the Sunda Plate. Its sense of motion is also kinematically congruent with the NW-SE translation along a transcurrent zone between the Philippine Mobile Belt and the Palawan Microcontinental Block on the western part of the Philippine archipelago. It is also consistent with the left-lateral motion of other structures within the zone, such as the Verde Passage Fault—another structure believed to be accommodating the NW-SE translation. Mapping of the CMF provides a key constraint in identifying the possible mechanism(s) involved in the dextral strike-slip motion of the 1994 Mindoro Earthquake ground rupture, which is subparallel to the CMF.

Morphometric and morphotectonic characteristics of a Tropical River Basin, North Kerala, India using geospatial technology

ABSTRACT This study delves into morphometric and morphotectonic analyses to unveil the evolutionary trajectory of Kerala's Korapuzha river basin. Employing advanced GIS and remote-sensing techniques, we explore the basin's geomorphological evolution and landform development. Our approach integrates data from a 1:50,000 scale toposheet and a 30 m resolution Digital Elevation Model (DEM), facilitating a detailed evaluation of basin characteristics. Through subdivision into KB-1 and KB-2 sub-basins, distinct morphometric patterns and morphotectonic features are discerned. The elongated basin configuration suggests ongoing tectonic activity, profoundly shaping its unique geomorphic evolution. To unravel tectonic influences, we employ morphometric indices, including the Relative Active Tectonic Index (IRAT), revealing neo-tectonic activity and dynamic landscape changes. Our study enriches our understanding of the Korapuzha river basin's evolution, illuminating the interplay between tectonic forces and geomorphic processes. Offering insights into tropical river systems, it contributes to broader landscape dynamic comprehension and informs sustainable land management practices. The IRAT calculation for the Korapuzha basin is based on the average of five geomorphic index classes, with resulting classifications indicating varying levels of tectonic activity. KB-1 and KB-2 sub-basins’ IRAT values enumerated as 2.2 and 2, respectively hence fall into classes 4 and 3, indicating low and moderate tectonic activity, respectively. The presence of tectonism in the study area revealed from geomorphic indices and IRAT, was acknowledged and evinced precisely by following the analysis of the SL index and GLA index method.

Tectonic evolution of Bursa Yenişehir Basin, Turkey from the Neogene to the Quaternary using a morphotectonic approach

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.

Rift obliquity in the Northern Volcanic Zone in Iceland using UAV-based structural data

Rift obliquity in the Northern Volcanic Zone in Iceland using UAV-based structural data

Unravelling the tectonic phases: The impact of the South Caspian Block on Late Cenozoic deformation in the Central Alborz, Iran

Paleostress reconstruction through polyphase fault-slip data of a multi-deformed region suffered collisional tectonics can lead to detecting the stress phases. Based on earthquakes’ focal mechanisms and morphotectonic features, multiple deformation phases model has been proposed for the Alborz Mountains located in the collision zone between the Arabian (Central Iran) and Eurasian (South Caspian block) plates during the Late Cenozoic. In this study, paleostress analysis has been carried out in an area bounded by two (Kandovan and Taleghan) regional faults in the Central Alborz Mountains using fault-slip data. This analysis resulted in the identification of three main tectonic phases. The first, compressional phase is proposed to cause the inversion of the Alborz Mountains’ major initial normal faults to reverse faults during the convergence of the Arabian and Eurasian plates. The second, transpressional phase is offered as a factor for the reactivation of the hidden Alborz basement faults to form the NE-striking left-lateral strike-slip faults on the sedimentary cover. The third, transtensional phase is suggested to be responsible for the development of the NNE–SSW left-lateral transtensional faults. It is proposed that the second and third paleostress phases are affected mainly by the indentation of the South Caspian Block into the Alborz Mountains during the Late Cenozoic.

The geomorphology and neotectonics of the Vaalputs Radioactive Waste Disposal Facility site, Namaqualand, South Africa: Palaeoseismological and geodynamic implications

Abstract The safe disposal of radioactive waste products remains a challenging and controversial issue, yet their burial in a stable geological environment is the option favoured by most countries. Past investigations of the Vaalputs facility in South Africa’s semi-arid Bushmanland Plateau demonstrated its suitability for the disposal of low-level, short-lived (<300 years) radioactive waste, but also the need for more data on hazardous seismotectonic and climatic processes for the potential storage of longer-lived spent nuclear fuel. We review and then provide new information on the regional geomorphological and morphotectonic features of the Bushmanland Plateau, focusing on pedogenic features and compressive shear fractures in the trenches excavated over the past two decades. The fractures, provisionally dated between ~75 ka and ~46 ka, resemble east-verging thrust faults of limited horizontal displacement (≤1 m) and die out at depths of 4 m. Having discounted a pedogenic origin, the shear fractures likely represent stress relief structures triggered by the seismogenic reactivation of one of the Quaternary active faults in the area. The most likely candidate is the Santab Fault Zone (SFZ), which has a strike length ≥20 km and a throw of up to ~5 m at its closest point (8 km) to the Vaalputs site. Regional remote sensing and off-site investigations in the Bushmanland Plateau relate the neotectonic episodes at Vaalputs and environs to a late Pleistocene climax of the Namaqualand seismic source zone. This zone is characterised by the Wegener Stress Anomaly, a long-lived ~northwest-southeast oriented compression that, at its apex in the Late Santonian, caused large scale folding and thrusting not only in Bushmanland and parts of central-southern Namibia, but also swept across the entire African plate.

Tectonic Analysis of the Tall Al Qarn Pressure Ridge, Dead Sea Transform Fault, Jordan

Jordan's Dead Sea Transform is made up of three morphotectonic elements: Wadi Araba, Dead Sea Basin, and Jordan Valley. A few pressure ridges and depressions exist in the Jordan Valley Fault. Among these, the Tall Al Qarn pressure ridge is one of the active Dead Sea Transform's morphotectonic features. Stratigraphically, the Waqqas (Miocene), Ghor Al Katar (Early Pleistocene), and Lisan (Late Pleistocene) Formations constitute the rock outcrops in the study area. The ridge was created when the sinistral strike-slip fault of the Jordan Valley bent rightward. The major structures include the Waqqas and Ghor Al Katar inclined beds, the NW-SE oriented normal and NE-SW reverse faults and the ESE-WNW oriented dextral strike-slip faults. Faults and folds indicate a local NW-SE compressional stress caused by the sinistral Jordan Valley Fault's right bending. The steeply dipping Ghor Al Katar strata, which are overlain by the horizontal Lisan beds, display a prominent angular unconformity. Many horizontal Lisan beds exhibit abundant synsedimentary deformational features, indicating the energetic seismic activity at that time.

Morphotectonics and paleoseismology of the North Darhad fault (SW Baikal Rift, Mongolia)

Morphotectonics and paleoseismology of the North Darhad fault (SW Baikal Rift, Mongolia)

Investigation of Morphotectonic Features in Drainage Basins by Geomorphic Analysis: The Example of Delibekirli (Hatay/Kırıkhan) Basin

Bu çalışmada temel amaç Anadolu’nun güneyinde, Amanos Dağları’ nın orta kesiminde (Orta Amanoslar) yer alan Delibekirli Havzası’nın morfotektonik özellikleri jeomorfik indislerle açıklamaktır. Delibekirli Havzası ve yakın çevresi, tektonik açıdan Ölü Deniz Fayı, Karasu Fayı ve Kıbrıs-Antakya Transform Fayı’nın karşılaştığı bölgeye yakın bir konumdadır. Ortalama eğim değeri 20,1° olan havzanın en yüksek noktası Amanoslar’da yer alan Daz Tepesi (1795 m)’dir. Kırıkhan Meteoroloji İstasyonu verilerine göre havzanın ortalama sıcaklık değeri 21,1 °C; yıllık yağış miktarı 579 mm; yıllık ortalama rüzgar hızı 1.5 m/sn ‘dir. Çalışmanın amacı kapsamında, akarsuyun hem aşındırma gücünü hem de aşındırdığı malzemelerin taşıma gücünü tespit için geliştirilen SL (Akarsu uzunluk-Boy Gradyan İndisi) indisi; sahanın jeomorfolojik gelişim evrelerinin belirlenmesi ve yorumlanmasında kullanılan Hc (Hipsometrik Eğri) ve Hi (Hipsometrik İntegral); sahanın morfolojik açıdan gençlik evresine yaklaşıp yaklaşmadığını anlamak için Vf (Vadi taban uzunluğu-Yükseklik Oranı) indisi; yerşekillerini faylar ile ilişkisini sayısal bir şekilde ortaya çıkarmaya yarayan Smf (Dağönü Sinüsitesi) indisi; sahanın yapısal unsur deformasyonlarını belirlemek ve tektonik yapıyı anlayabilmek için çizgisellik analizi; aktif tektonik deformasyonun şiddeti ve yönünü anlayabilmek için ise T (Topoğrafik Simetri) ve Af (Asimetri Faktörü) uygulanmıştır. Farklı litolojik birimlerden oluşan çalışma sahasının jeomorfolojik gelişimi tektonik hareketler, iklim, karstlaşma ve akarsu aşındırmasının etkisi altında sürdürmektedir. 
 Havzadaki çizgisellikler tektonik yapı tarafından denetlenmektedir. Tektonik süreçler aktif olarak etkinliklerini sürdürüp sahayı yükseltmeye (uplift) devam ederken diğer yandan flüvyal süreçlerin de etkinliklerini sürdürdüğü ve tektonik aktiviteden etkilendiği anlaşılmaktadır. Yükselen sahada akarsuların yataklarını derine doğru kazıdığı, sahasının tektonik manada çarpıldığı ve ana akarsu kolunun, akış istikametine göre sol yönlü olduğu (tilt) sonucuna varılmıştır. Yine akarsu ötelenmeleri ve çizgisellikler sahaya sol yönlü oblik fayların yerleştiğini göstermektedir.

Slope instabilities and evolution of tectonic geomorphology along the strike of the Main Boundary Thrust zone in the western Himalaya, India

Slope instabilities and evolution of tectonic geomorphology along the strike of the Main Boundary Thrust zone in the western Himalaya, India

Magnetotelluric imaging reveals fragmented crustal blocks beneath the Konkan plains adjoining the Western Ghats, Deccan Volcanic Province, India

Magnetotelluric imaging reveals fragmented crustal blocks beneath the Konkan plains adjoining the Western Ghats, Deccan Volcanic Province, India

Morphotectonic Features in the Middle Biferno River Valley: The Case of Ponte Liscione Dam (Central Italy)

This paper presents a morphometric and structural-geomorphological approach to identifying morphotectonic features across an area underlain by lithologies that do not easily record tectonic deformations but are widely affected by seismic activity. The middle Biferno River Valley (Central Italy) was chosen as a study area. It was investigated through analyses performed from the drainage basin scale (Biferno River) to the local scale (Ponte Liscione Dam). This methodological approach was applied to investigate the impact of morphotectonic processes in the study area, providing a geomorphology-based contribution to landscape evolution. The aim of the work was to discriminate the main morphotectonic elements acting in the complex tectonic framework of the study area by means of a combination of morphometric, morphotectonic, and structural-geomorphological analyses. The resulting data allowed us to identify three main systems of tectonic elements (F1, F2, and F3), which are attributable to compressive and extensional kinematics, as already reported in previous thematic studies. The tectonic setting reflects the geodynamic framework of the Periadriatic region, as highlighted by the distribution of seismogenic sources and the historical to recent seismicity. Finally, the present work could act as a valuable scientific tool for any geomorphological studies aimed at better defining the impact of morphotectonic processes in similar tectonically active regions hosting important and strategic artificial dams.

Tectonics of the Iberian continental margins and abyssal plains

ABSTRACT The tectonic map at scale 1:1,750,000 presented in this work shows an update of the existing knowledge of the main tectonic and volcanic structures along the Iberian continental margins and abyssal plains. The morphotectonic trends around Iberia recorded superposed geodynamic processes linked to the opening of the North Atlantic Ocean since the Mesozoic and the evolution of the Mediterranean Sea during the Cenozoic, as well as the reactivation of Hercynian faults and the formation of new tectonic structures during the Alpine orogeny. This map is based on the interpretation of the digital bathymetric model and other geophysical data from our own studies, and those from other authors. The morphotectonic features in this map provides a basis for the recognition of the tectonic control at lithospheric plate scale and the establishment of potential tectonic and volcanic risk zones.

Constraints on near-ridge magmatism using 40Ar/39Ar geochronology of enriched MORB from the 8°20' N seamount chain

Constraints on near-ridge magmatism using 40Ar/39Ar geochronology of enriched MORB from the 8°20' N seamount chain

Evolution of the Limpopo River Basin in Botswana based on morphometric and morphotectonic features from selected rivers using GIS techniques

ABSTRACT This study used morphometric techniques to generate new information describing the evolution and hydrogeological behaviour of the Limpopo River Basin in Botswana, based on the analysis of drainage surface features, form, and size. Drainage basins provide basic information on their evolution, which, when quantified, yield information on the interaction between tectonics, climatic, and surface processes. Drainage networks were extracted from the Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) (90 m × 90 m), and subsequently, morphometry indices were computed using ArcGIS 10.5. Drainage network extraction was performed using the Arc Hydro extension in ArcGIS 10.5. ArcGIS 10.5 image processing technique was used to extract lineaments and create rose diagrams. The results showed that the Limpopo sub-basins in Botswana were drained by fourth- and fifth-order streams, with a total drainage area of 107, 871 km2. Additionally, the basin asymmetry and mean bifurcation ratios showed tilting in the sub-basins, suggesting tectonic instability and structural control in a low – to-moderate active tectonic zone. The sub-basins also had a coarse texture, indicating a high infiltration capacity. These results are essential for planning and managing watershed systems, flood risk assessment, and potential groundwater assessment for the different sub-basins of the Limpopo River Basin in Botswana.

DEM-based directional statistical examination of linear features: the case study in Bükk Mountains (NE Hungary)

Analysis of linear features such as faults, valleys, interfluves, and escarpments is a commonly used method in structural morphologic and structural geologic research. The aim of our study was to investigate the relationship between the linear features by directional statistical analysis, and we also examined the applicability of this method in a research area with a complex geological structure. The study area was the Bükk Mountains (NE Hungary) and its two catchment areas. The analysed features (drainage network, lineaments and dominant aspect) were derived from a DEM. As a result of the research, we found that in the Sajó catchment, the direction of lineaments does not coincide with the direction of the valleys and structural elements, nor the dominant aspect, while in the Tisza watershed, the orientation of the main structural features notably differs from the direction of the other 3 feature sets. In our opinion, this finding can be explained in three possible ways. The first possibility is that the applied method does not provide reliable results in a geologically complex area. The second explanation is that regional structural processes may affect drainage network evolution and the dominant aspect. The other explanation is that there may have been unknown structural elements in the research area, which affect the recent geomorphological settings and processes. The results draw attention to the fact that besides the unmapped faults, there might be other factors affecting geomorphological processes (e.g., resistance to denudation of different rock types, microclimate), which have not been taken into account so far. The research was based only on directional statistical examinations; further geological and geophysical analyses are required to prove the existence of these hypothetical morphotectonic features.

Delineated and analysis of morphotectonic features utilizing ASTER GDEM/DSM and Radar dataset: An example is Gabel El-Ekma Durba-Arab central Gulf of Suez, Egypt.

Delineated and analysis of morphotectonic features utilizing ASTER GDEM/DSM and Radar dataset: An example is Gabel El-Ekma Durba-Arab central Gulf of Suez, Egypt.

Active tectonics in the Main Boundary Thrust zone, Garhwal Himalaya, as evident from palaeoseismic signatures, morphotectonic features and PSI base ground deformation

In the Garhwal Himalaya, the steeply inclined Main Boundary Thrust (MBT) is characterized by landforms that indicate towards tectonic activity in the recent past. Linear active fault trace, sub‐recent fault scarps, strath terrace, uplifted terraces, deflected drainage, and triangular facet cones are some of the morphotectonic evidences of recent tectonic activity along the MBT. The MBT is defined by active fault trace in the form of linear depression and shows a prominent slope break across it. Thrusting of the Lesser Himalayan bedrocks over the colluvial deposits and back tilting of the colluvial deposits are also observed in the MBT zone. The formation of the sag pond and the deposition of the Quaternary lacustrine sediments followed by the deformation of the lacustrine deposits indicate phases of tectonic activities along the MBT. The later phase of deformation is represented by the folded lacustrine and colluvial deposits, where the amplitude of the fold measures about 3 m‐high and the deformed section measures about 23 m in length. The ongoing deformation patterns of the MBT zone have also been monitored with the help of Synthetic Aperture Radar‐based time series analysis. We used Sentinel‐1C dataset in ascending direction with polarization of the VV+ VH acquired between December 2, 2017 to September 7, 2021 to identify phase changes caused by ongoing active deformation. The Persistent Scatterer Interferometry (PSI) result based on Sentinel‐1A suggests that the Dehradun–Mussoorie and adjoining region has undergone an average deformation of 5.5 to −11 mm/year and the ground displacement of 1.5 to −3.8 cm. The time series analysis reveals that the Mussoorie hills in the MBT zone have higher rate of deformation.

Assessing active and capable faulting as best practice for post-earthquake reconstruction activities: the Sant’Eutizio Abbey case study, in the epicentral area of the 2016 central Italy seismic sequence

Surface faulting is, together with strong ground shaking, a hazard associated with major earthquake faults. Assessing surface faulting potential of a given active tectonic structure is a fundamental prerequisite to adequately plan the use of territories and to perform new constructions, in order to act practices aimed to mitigate the associated risk. Assessing the surface faulting potential represents also ground for correctly performing re-construction and retrofitting of buildings and infrastructures during post-earthquake activities. We investigated a branch of a major seismogenic normal fault in the central Apennines of Italy, the Campi-Preci fault, along which the monumental Sant’Eutizio Abbey is located. The medieval Abbey is one of the most important cultural/religious edifices of the central Apennines, heavily damaged by the MW 6.5 October 30, 2016, earthquake, focused a few km to the south. Our study, based on field geological, geomorphological and structural survey and trenching investigations revealed that I) the trace of the Campi-Preci active fault branch is not actually located where presently reported in the available literature, II) the supposed morpho-tectonic features (basically, some km-long scarp carved on the Meso-Cenozoic carbonate bedrock), that suggested the presence of the fault segment in the area of the Sant’Eutizio Abbey, are not related to the active fault but are probably associated to a presently inactive reverse fault and III) the Sant’Eutizio Abbey is likely not potentially affected by primary surface faulting. Our work highlights that only a comprehensive multidisciplinary approach allows to correctly assess surface faulting potential in both seismotectonic and engineering perspectives.

Geometry and Segmentation of the Philippine Fault in Surigao Strait

On 10 February 2017, a MS 6.7 earthquake, whose epicenter was located in Surigao Strait, struck the province of Surigao del Norte, causing numerous geologic impacts and damages to infrastructure. Field investigation conducted immediately after the earthquake revealed an NNW-SSE-striking surface rupture that extends 4.1 km inland. The remaining 20 km of the surface rupture, based on the computed magnitude-surface rupture length empirical relationship, was inferred to be located offshore along the Philippine Fault in Surigao Strait. We investigated the geometry of the fault in Surigao Strait by identifying morphotectonic features and geologic structures using offshore geophysical data that include multibeam bathymetry, sub-bottom profiles, and seismic reflection profiles. We interpreted several fault-related features such as pull-apart basin, offset channels, linear valleys, and folds and identified four fault segments, which are named the Maka-andog Strand, Surigao-Sanghid Strand, West Sanghid Strand, and Panaon Strand. Based on fault length, these segments are capable of generating MW 6.4 to 6.9 earthquakes. We have determined that surface rupture most probably extends along the entire length of the Surigao-Saghid Strand that generated the 2017 MS 6.7 earthquake. The identified morphotectonic features, presence of strike-slip with significant normal displacement in offshore geophysical imaging data, and focal mechanism all suggest that Philippine Fault in Surigao Strait is dominated by transtensional deformation, which supports the interpretations by previous authors.