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The paper presents new data on brackish-water Upper Pliocene and Lower Pleistocene deposits that were studied in the Demirkent (Kars) and Pekecik (Erzurum) sections, NE Turkey. The Demirkent section is situated in the southwestern slope of the Shirak Late Cenozoic intermontane basin near the Turkish-Armenian border. The Pekecik section is situated to the SW of the Demirkent in the southwestern slope of the Horasan intermontane basin. Both sections are composed of clays, silts, and poorly cemented fine-grained sandstones and contain the brackish-water dinocysts of the Akchagylian type. The age of the deposits is determined by combined analysis of associations of molluscs and small mammals, palynological spectra, including dinocysts and algae, and magnetostratigraphic data. The Demirkent and Pekecik sections are dated to the Late Pliocene (Piacenzian). The maximum spread of the Akchagylian transgression influenced the inland areas of NE Turkey prior to the early Gelasian. The pollen spectra demonstrate progressive aridisation during sedimentation of the lower part of the Demirkent section and the wetter and cooler climate during sedimentation of the lower part of the Pekecik section. The analysis of brackish-water dinocysts and fresh-water algae in different beds of the Demirkent section indicates gradual freshening of the basin probably due to the sea level fall. In the Pekecik section, the brackish-water dinocysts are found in the lower part that is covered by the lignite-bearing layers without signs of marine influence. Recent altitudes of the Akchagylian brackish-water deposits give a possibility to estimate magnitudes and average rates of the Quaternary uplift of the western Lesser Caucasus. The elevation of the Upper Pliocene deposits of Demirkent and Pekecik sections shows the uplift rate of ca. 0.6–0.7 mm per year during 2.6 Ma.

Central Asia exceeds neighboring territories in the intensity of Quaternary uplifts and active faulting. The active fault kinematics differ in the northeast of the region, from Middle Tibet to Eastern Sayan, and its southern and western parts, including the Himalayas, the Pamir–Punjab syntaxis, and the region north of Gorny and Mongolian Altai. The northeast is dominated by latitudinal left-lateral strike-slips, while the south and west, by right-lateral strike-slips and northwest- and latitudinally striking overthrusts. The features of active tectonics are governed by the upper mantle structure, studied in three horizontal sections. The highest mountain systems, with sharply reduced P-wave velocities and lower rock densities, are distinguished in the section 67 km deep (crust/mantle boundary zone and upper lithospheric mantle). Dilatation became the main reason behind the intensive uplift of these mountain systems and, partially, Tibet. The sections with depths of 158 and 293 km revealed heterogeneous structures of the upper mantle of Central Asia. In its eastern part, P-wave velocities were significantly reduced by the influence of Tibetan and Khangai intramantle plumes. Here, lateral extension exceeded lateral shortening, and the lithosphere could not transfer the pressure of the Indian Platform to the northern tectonic zones. Dilatation of the upper mantle caused the uplift of Tibet and the Khangai Plateau. Plume-related currents in upper mantle caused left-lateral strike-slips along latitudinal faults. In the south and west of Central Asia, P-wave velocities and the density of the upper mantle increase. In the south, the lithosphere of the Indian Platform thickens and underthrusts the Himalayas and Southern Tibet. Active thrusts, right-lateral strike-slips, and oblique-slip thrusts in the western and northwestern parts of Central Asia express horizontal compression of lithospheric blocks. The heterogeneous density of the lithosphere resulted in rotation of the compressed blocks, so that shear decreased and even faded along the faults.

Studies carried out by the authors show that the uplift of Central Asia situated between the eastern Alpine–Himalayan and western Altai–Stanovoy orogenic belts formed in the neotectonic epoch. Major elements of the neotectonic structure and compiled upper mantle sections showing the difference in P-wave velocities from the standard values for the corresponding depths are analyzed. It is found that underthrusting of the high-velocity uppermost mantle of the Indian Platform beneath the Himalayas produced deformational thickening and a significant decrease in the density of the lithosphere. This led to uplift of the Himalayas, Karakorum, Hindu Kush, Pamirs, Southern and Western Tibet, and Western Kunlun, accelerating in the Pliocene–Quaternary. The seismic velocities are lowered under the rest of Central Asia except for some peripheral mountain systems. Two intramantle plumes are identified. The Tibetan plume is traced from depths of ~1600 km. The upper mantle alterations initiated by this plume were the main source of the Tibet uplift. The Khangai Plume is traced from depths of ~1250 km. The Khangai plume, together with its Khentei branch, caused the formation of the Khangai and Khentei Highlands and Neogene–Quaternary basaltic volcanism. The influence of sublithosheric flows spreading out of the Tibetan and Khangai plumes, as well as the Ethiopian–Afar superplume, caused a decrease in the density of the upper mantle, Neogene–Quaternary flexural deformation, and Pliocene–Quaternary uplift of the Central and Eastern Tien Shan, Gobi Altai, and partly, Mongolian Altai. The seismic wave velocities in the upper mantle are increased under the Western Tien Shan, Junggar Alatau, Gorny Altai, Western Sayan, and northwestern Mongolian Altai. The source of deformation and uplift is the collisional interaction of lithospheric blocks, while the magnitudes of uplift are lower than in mountain systems with a decreased density of the upper mantle.

—Mesozoic‒Cenozoic tectonic zoning and its evolution are characterized by analysis of geological data on the Black Sea–Caucasus–Caspian region. The following tectonic zones were located in succession to the north of the Mesotethys Ocean in the Early Jurassic: the mobile zone on the Hercynian basement; the Moesian–Black Sea–Trans-Caucasus minor plate with the Precambrian–Baikalian basement, which experienced the Hercynian tectonic and magmatic reworking in the Lesser Caucasus; the relatively deep-water Crimean–Caucasus–South Caspian Trough on the continental crust that thinned in the process of its extension; and the southern margin of the Scythian Plate with a thin sedimentary cover. In the Caucasus, the southern and northern slopes of the deep-water axial trough have been identified, where thick shelf deposits accumulated. Subduction began in the northern margin of the Mesotethys in the Bajocian and island-arc volcanism occurred in the Somkheti–Karabakh zone and Eastern Pontides, the Trans-Caucasus part of the Moesian–Black Sea–Trans-Caucasus Plate, and the southern slope of the Crimean–Caucasus–South Caspian Trough. The volcanism in the Somkheti‒Karabakh zone and the Eastern Pontides lasted into the Cretaceous. The area of island-arc volcanism was inherited by the Eocene collisional volcanic belt. The Crimean part of the Crimean–Caucasus–South Caspian Trough and its northern slope in the Caucasus underwent Cimmerian deformation and shelf facies accumulated there after deformation up to the Miocene, while relatively deep-water sedimentation occurred in the Caucasus–South Caspian part of the Crimean–Caucasus–South Caspian Trough. The Western and Eastern Black Sea basins of extension originated in the Cretaceous on the continental crust of the Moesian–Black Sea–Trans-Caucasus Plate, which thinned in the basins as they were filled by Late Cretaceous, Paleogene, and Miocene marine deposits. In the Pliocene–Quaternary, total undifferentiated subsidence and sedimentation occurred in the Black Sea, and subsidence of the South Caspian, Azov‒Kuban, and Terek‒Derbent basins accelerated. Several phases of Middle and Late Miocene fault–fold deformation formed local uplifts in the mountainous parts of the region. The total uplift of mountain systems occurred in the Pliocene–Quaternary. The formed crustal structures and the velocity inhomogeneities in the upper mantle were compared, which showed that many inhomogeneities were obliterated by sublithosphere flows that spread out of the Ethiopian–Afar superplume. In mantle volumes, where the flow intensity weakened, relics of subducted slabs remained. They are slabs of the Neotethys in the Zagros and the Mesothethys in the Lower Kura Basin, and slabs of the Scythian Plate lithosphere underthrust under the Central Caucasus and more weakly under Steppe Crimea during the Hercynian subduction.

Active faults are those faults on which movement is possible in the future. It draws particular attention to active faults in geodynamic studies and seismic hazard assessment. Here we present a high-detail continental-scale geodatabase: The Active Faults of Eurasia Database (AFEAD). It comprises 46,775 objects stored in the shapefile format with spatial detail sufficient for a map of scale 1:1M. Fault sense, a rank of confidence in activity, a rank of slip rate, and a reference to source publications are provided for each database entry. Where possible, it is supplemented with a fault name, fault zone name, abbreviated fault parameters (e.g., slip rate, age of the last motion, total offset), and text information from the sources. The database was collected from 612 sources, including regional maps, databases, and research papers. AFEAD facilitates a spatial search for local studies. It provides sufficient detail for planning a study of a particular fault system and guides deeper bibliographical investigations if needed. This scenario is particularly significant for vast Central and North Asia areas, where most studies are available only in Russian and hardcopy. Moreover, the database model provides the basis for GIS-based regional and continental-scale integrative studies. The database is available at https://doi.org/10.13140/RG.2.2.10333.74726 and via web map at http://neotec.ginras.ru/index/mapbox/database_map.html (last access: July 30, 2021). Some database representations with supplementary data are hosted at http://neotec.ginras.ru/index/english/database_eng.html.

Majority of researchers consider the Arabian-Caucasus region as a corridor for migration of earliest hominins from their African motherland to Eurasia. The paper is devoted to geological position of main stratified localities of the earliest Paleolithic industries in the Arabian-Caucasus region and estimation of environment of creators of these industries. The following early Paleolithic localities are analyzed: ‘Ubeidiya in Israel, middle Orontes River, Halabiyeh-Zalabiyeh area in the Euphrates River valley, and Ain al Fil in Syria, Dursunlu in Central Turkey, Sambayat, Bostancik, Eskimalatya, and Kovancilar in Eastern Turkey, Karakhach, Muradovo, Agvoric, and Jradzor in NW Armenia, Dmanisi in Southern Georgia, the Azykh cave in Nagornyi Karabakh, Muhkai II in Dagestan, and Kermek in the Taman Peninsula. The evolution of large and small mammals and palynological data on changes of vegetation from the Late Pliocene to the early Middle Pleistocene are studied to determine the age of the earliest Paleolithic industries and climatic conditions of that epoch. Combined analysis of paleontological, paleomagnetic and radio-isotopic data and geological correlation of the sections available for the Halabiyeh-Zalabiyeh, Sambayat, Kovancilar, Karakhach, Dmanisi, Muhkai II, and Kermek localities shows that their age is ranged in time interval ca. 2.0–1.7 Ma. The 1.7–1.6 Ma age of the lowest layers of ‘Ubeidiya with Oldowan-type artefacts probably marks the end of this epoch. Removal of topographic effects of the late Calabrian and younger tectonic uplifts and offsets on major strike-slip faults shows that the topography of the late Gelasian – early Calabrian was much lower and less differentiated and main river systems were more passable than in the present time. The climate of the end of Gelasian was wet and relatively warm, with meadow-steppe and forest-steppe savanna-type vegetation in basins and valleys and coniferous and coniferous–broad-leaved forests in the mountains. Abundance of vegetation was supported by water resources of numerous rivers, lakes, and springs in the intermountain basins and valleys that were controlled partly by fault activity. This stimulated abundance of herbivorous mammals. In spite of relative aridisation at the beginning of Calabrian, vegetation continued to be freely available for herbivores. Hominin dispersal into the region was supported by rich resources of herbivores during the late Gelasian – early Calabrian time.

Studies in paleomagnetism, structural geology, and paleontology (mammals, molluscs, palynology) in the coastal sections of the Taman Peninsula north-eastern part (2017–18) resulted in definition of three sedimentary members. The sandy and clayey lower member (I) formed at 2.1–1.7 Ma. It contains a normally magnetised zone within deposits of reversed polarity correlated to the Olduvai Subchron and the Matuyama Chron. The middle member (II) is composed of the basal pebbles overlain by sands. The reversely magnetised deposits hosting the Sinyaya Balka site, the type locality of the Tamanian faunal complex, is correlated to the basal bed of the middle member II. The overlying sands are normally magnetised (Jaramillo Subchron) in the lower part and show reverse polarity (late Matuyama Chron) in the upper part. The member II is dated in the range of 1.3–0.78 Ma. The silty upper member (III) represents Middle-Late Pleistocene. The dissimilar displacement degree of the members reflect developmental stages of the Quaternary deformation. The member I is characterised by dip angles up to 70° is fragmented by faults into blocks. The member II filled the relief of the eroded surface of the Member I and also displaced by faults. The faulting separated the bone-bearing body of the Taman faunal complex as a rock land-slide. The attitude of the member III outline an anticline with a gentle south-western and a steeper north-eastern limbs eroded by land-slides and marine abrasion. During its entire life the anticline was affected by mud volcanism. The anticline continues its development at the present stage.

Studies in paleomagnetism, structural geology, and paleontology (mammals, mollusks, palynology) in the coastal sections of the Taman Peninsula north-western part (2017–18) resulted in definition of three sedimentary sequences. The sandy and clayey lower sequence (I) formed at 2.1–1.7 Ma. It contains a normally magnetised zone within deposits of reversed polarity correlated to the Olduvai Subchron and the Matuyama Chron. The middle sequence (II) is composed of the basal pebbles overlain by sands. The reversely magnetised deposits hosting the Sinyaya Balka site, the type locality of the Tamanian faunal complex, is correlated to the basal bed of the middle sequence II. The overlying sands are normally magnetised (Jaramillo Subchron) in the lower part and show reverse polarity (late Matuyama Chron) in the upper part. The sequence II is dated in the range of 1.3–0.78 Ma. The silty upper sequence (III) represents Middle-Late Pleistocene. The dissimilar displacement degree of the sequences reflect developmental stages of the Quaternary deformation. The sequence I is characterised by dip angles up to 70° is fragmented by faults into blocks. The sequence II filled the relief of the eroded surface of the sequence Member I and also displaced by faults. The faulting separated the bone-bearing body of the Taman faunal complex as a rock land-slide. The attitude of the member III outline an anticline with a gentle south-western and a steeper north-eastern limbs eroded by land-slides and marine abrasion. During its entire life the anticline was affected by mud volcanism. The anticline continues its development at the present stage.

Resume Pendant tres longtemps, la communaute scientifique supposait que la culture acheuleenne ne se soit exprimee sur le Plateau d’Armenie ainsi que dans les regions voisines du Caucase uniquement que par sa phase tardive, donc a la deuxieme moitie du Pleistocene moyen. Au cours des dernieres annees, la mission Armeno-Russe a decouvert et etudie des industries acheuleennes beaucoup plus anciennes, issues des sites localises au Nord de l’Armenie (dans la depression intermountaine de Lori). Ces industries, representees par des outils de type archaique (gros bifaces, pics, choppers, ciseaux, racloirs, pointes, etc.) ont ete decouvertes dans trois gisements d’origine proluviale. Dans le site de Karakhatch, ce type d’industrie est depose dans les niveaux inferieurs sous le tuf volcanique. L’etude par U/Pb de ce niveau de tuf propose une serie de datations comprises entre 1,944 ± 0,046 et 1,75 ± 0,02 Ma. L’etude paleomagnetique a demontre la polarite inverse du tuf et la polarite normale des depots sous-jacents ; ce fait permet, en correlation avec les datations, d’attribuer les couches acheuleennes du site de Karakhatch au Pleistocene inferieur, notamment a l’episode d’Oldoway et a la periode de Matuyama superieur. L’âge estime et les caracteristiques techno-morphologiques des outils les renvoient a l’Acheuleen inferieur. La datation du gisement de Muradovo ne parait pas possible, cependant ses industries tres anciennes et les couches archeologiques qui les ont fournies, trouvent des equivalents dans l’ensemble des couches surmonte par des tufs du site de Karakhatch. Le gisement de Kutran I a mis au jour une sequence de paleosols avec des outils acheuleens de caracteristiques similaires (bifaces, pics, chopper, etc.). La couche la plus ancienne est datee de plus d’1,5 Ma, la couche superieure est attribuee a tout debut du Pleistocene moyen ; cela veut dire qu’il est possible de parler d’Acheuleen inferieur et de sa transition vers l’Acheuleen moyen. Le caractere specifique et l’âge obtenu admettent qu’un Acheuleen inferieur en Armenie ait pu se former independamment de l’Acheuleen inferieur d’Afrique, dont l’âge estime ne remonte pas avant 1,76 Ma. Il faut egalement noter que sur le territoire voisin de Georgie, a peu pres a l’epoque de l’apparition de l’Acheuleen en Armenie, existait deja le site oldowayen de Dmanissi.

Early Palaeolithic finds older than Acheulean were unknown in Eastern Anatolia until recently. During exploratory works carried out by a joint Russian-Turkish expedition in the Euphrates River basin (2014–2016), several stratified Early Palaeolithic localities were found. Lithic finds are represented by choppers, picks, retouched tools, and flakes. A similar stone tool industry has been found in the Caucasus (Armenia, Dagestan). In addition to the archaeological typological dating of lithic tools in eastern Turkey, geomorphological, stratigraphic, paleontological, and paleomagnetic records also confirm the Early Pleistocene age of the localities. Some of these sites are dated to before the Olduvai subchron, i.e., ∼2 Ma. New Early Palaeolithic discoveries in Eastern Turkey are important for the study of the oldest human cultures of the Middle East and the Caucasus. Acheulean and Middle Palaeolithic stone tools were also found in the lower river terraces of tributaries of the Euphrates, south of the Taurus Mountains. These finds were used to date the terraces.

The Pliocene–Quaternary paleogeography of the Euphrates River valley changed due to sinistral movements on the East-Anatolian Fault Zone (EAFZ) and the Taurus Ridge rise by movements on the South-Taurus Thrust. Evidence of these changes is based on studies of the Pliocene–Quaternary deposits of the Euphrates River basin to the north and to the south of the Taurus Ridge and the Late Cenozoic deformation including offsets on the EAFZ. Combination of methods was used to date the Pliocene–Quaternary deposits. It includes geological and geomorphic analysis and correlation of sections, determination of remanent magnetization, paleontological and archaeological finds, pollen analysis, and K-Ar dating of volcanic rocks. To the north of the Taurus Ridge, the Late Miocene tectonic depressions were filled by lakes connected by braided streams. In the Early Pliocene, the Euphrates and Murat river valleys formed and the Euphrates flew to the south westwards of its recent position, via the graben-like trough of the Sultan-Suyu River valley and farther to the Erikdere that are recent Euphrates tributaries. The flow was interrupted later because of some desiccation and rise of the Taurus Ridge. The flow recommenced in the end Gelasian – early Calabrian via the Goksu-Cayi and Erikdere valleys consecutively and was interrupted again. At the end of Calabrian (∼0.8–0.9 Ma), the Euphrates waters found the recent way via the Taurus Ridge and the former upstream bottoms of the Euphrates and its tributaries valleys became a vast upper terrace. After this, the Taurus Ridge rose by more than 330 m. Lower terraces were formed because of the tectonic uplift that was more intense to the north of the Taurus Ridge (0.13–0.16 mm/year), than to the south of it (0.1 mm/year). The new-formed segment of the Euphrates valley was offset on the EAFZ at 12 km that gives the slip rate of 13–15 mm/year.

The study concerns two deep sources of tectonic processes in Late Mesozoic and Cenozoic which influence is transferred and enforced on the spheroid surface – Earth crust. The first source is mantle convection. Its upgoing branches are comprised by mantle superplumes from which the upper mantle flows spreads laterally. Downgoing convection branches are comprised by detached highly metamorphosed fragments of thickened continental lithosphere and partially by subducted slabs, submerged lower than transitional mantle layer (~410–680 km). Major of subduction zones are transformed to subhorizontal lenses at the transitional layer depth participating in upper mantle convection. Coupled with total mantle convection it defines plate tectonic processes and lithosphere density loose, bringing rise amplifying during mountain formation. The second source is outer core flows reflected in magnetic field inversions, which are more frequent during or before of major of tectonic activity phases (phases of compression and transpression deformations strengthen). Inversion frequency rises during neotectonic orogeny. It is supposed, that Earth core flows change its spheroid parameters, which brings to the appearance of volume forces, affecting almost immediately in geological time. Thus core flows contribute to global character of tectonic phases occurrences and synchronicity for superposition of modern mountain formation main phase with plate tectonic processes.

The authors consider the chronological relation of two groups of phenomena in the history of the Earth over the last 150 mln years. One of them is relatively short (a few million years) tectonic phases, or orogenic phases, identified by H.W. Stille in 1924 and characterized by an increase in compressive deformation in mobile belts of the Earth. Deformations that occur during such phases are quite explicable by collisional interactions of lithospheric plates. However, these interactions do not explain the synchronous occurrence of phases in different belts and on different continents. The other group is the frequency of magnetic reversals, i.e., changes such that the positions of magnetic north and magnetic south are interchanged. Tectonic phases are more frequent in epochs of frequent geomagnetic reversals. During the last 24 mln years, when geomagnetic reversals were especially numerous, tectonic phases came one after another in short intervals. An emerging trend for them is the lagging of phase peaks by one to two million years relative to the most frequent magnetic reversals. The chronological relations identified show that tectonic phases are determined not only by geodynamic processes in the lithosphere but also by the action of energy pulses that occur in the Earth’s core and at the boundary of the core with the mantle, where the Earth’s magnetic field is generated. On the geological time scale, this interaction takes place quickly, which excludes energy pulse convection and prompts the search for other mechanisms of this transfer. It is possible that it takes place because the lithosphere is affected by alternating body forces that occur under a change in currents in the core, which is followed by changes in the mode of the Earth’s rotation and the adaptation to it of lithospheric masses.

The estimated rates of upper mantle sublithospheric flows in the Hawaii–Emperor Range and Ethiopia–Arabia–Caucasus systems are reported. In the Hawaii–Emperor Range system, calculation is based on motion of the asthenospheric flow and the plate moved by it over the branch of the Central Pacific plume. The travel rate has been determined based on the position of variably aged volcanoes (up to 76 Ma) with respect to the active Kilauea Volcano. As for the Ethiopia–Arabia–Caucasus system, the age of volcanic eruptions (55–2.8 Ma) has been used to estimate the asthenospheric flow from the Ethiopian–Afar superplume in the northern bearing lines. Both systems are characterized by variations in a rate of the upper mantle flows in different epochs from 4 to 12 cm/yr, about 8 cm/yr on average. Analysis of the global seismic tomographic data has made it possible to reveal rock volumes with higher seismic wave velocities under ancient cratons; rocks reach a depth of more than 2000 km and are interpreted as detached fragments of the thickened continental lithosphere. Such volumes on both sides of the Atlantic Ocean were submerged at an average velocity of 0.9–1.0 cm/yr along with its opening. The estimated rates of the mantle flows clarify the deformation properties of the mantle and regulate the numerical models of mantle convection.

New data on the stratigraphy, faults, and formation history of lower to middle Pleistocene rocks in Late Cenozoic basins of northwestern Armenia are presented. It has been established that the low-mountain topography created by tectonic movements and volcanic activity existed in the region by the onset of the Pleistocene. The manifestations of two geodynamic structure-forming factors became clear in Pleistocene: (i) collisional interaction of plates due to near-meridional compression and (ii) deep tectogenesis and magma formation expressed in the distribution of vertical movements and volcanism. The general uplift of the territory, which was also related to deep processes, reached 350–500 m in basins and 600–800 m in mountain ranges over the last 0.5 Ma. The early Pleistocene (~1.8 Ma) low- and medium-mountain topography has been reconstructed by subtraction of the latest deformations and uplift of the territory. Ancient human ancestry appeared at that time.

The Quaternary stratigraphy and tectonic development of the southern Javakheti Upland and the adjacent Upper Akhurian and Lori uplifted basins in NW Armenia (Lesser Caucasus) and geological position of the early and middle Acheulian lithic industries were studied using a multi-method approach. Studies of sedimentary sections, petrological and geochemical correlation of lavas and tuffs, K–Ar dating of volcanic rocks and SIMS 238U–206Pb dating of tuffs, examination of obtained fossils and pollen analysis, and determination of remanent magnetic polarity of volcanic rocks and clastic sediments have been used to compile the stratigraphic scheme and to estimate the age of units. The low-mountain topography was differentiated to ridges and basins to the beginning of Quaternary. The eruptions of basalts and basaltic andesites evened topography of the Upper Akhurian and Lori basins in the Gelasian. The lava flows spread along big river valleys at tens of kilometers. At the late Gelasian, the eruptions of basaltic trachyandesites, trachyandesites and dacites replaced the basaltic eruptions. The latter dammed the Akhurian River flowing to the south and the upper Akhurian River found the flowing to the east via the valley-like depression of the Karakhach Pass to the Dzoraghet-Debed valley. The course-grained tuffaceous-clastic Karakhach unit was deposited during the Olduvai subchron (not earlier than 1.9–1.85 Ma) and the earliest Calabrian. The water transit between the Upper Akhurian and Lori basins was interrupted later because of rise of the Karakhach Pass. Volcanic activity renewed for a short time in the early Calabrian (∼1.7 and 1.5–1.4 Ma). The end Calabrian and earliest Middle Pleistocene sedimentation (∼1–0.5 Ma) occurred in stagnant water, partly lacustrine conditions. This was expressed by formation of the relatively fine-grained Kurtan unit. During the last ∼0.5 Ma, the region underwent flexure-fault deformation and tectonic uplift at 350–800 m. The epoch of formation of the Karakhach unit was characterized by middle mountain topography and humid climate. Not later than 1.85 Ma, the region was occupied by the earliest hominines producing lithic industries of the Early Acheulian aspect. They contained crude hand-axes and other macro-tools, made of local dacite and basalt (sites of Karakhach, Muradovo and Agvorik). Early appearance of these industries might be caused by natural parting of dacite and basalt to tabulated fragments that gave a possibility to make such macro-tools. The Middle Acheulian artifacts were found in the Kurtan I section of the Kurtan unit.

The spatial, chronological, and genetic relationships of recent (Late Alpine) collisions to mountain building are considered at three levels of scale: (i) in separate zones of the Arabian–Caucasus segment of the Alpine–Himalayan Orogenic Belt, (ii) throughout the central segment of this belt from the Alps to the Himalalayas, and (iii) in Central Asia and other mountain belts of continents. Three stages of mountain building are distinguished at all three levels. The first stage starts with widespread collision and similar plate interactions from the end of the Eocene to the middle Miocene and is expressed in the formation of uplifts, commonly no higher than the moderately elevated level in regions that concentrate deformations of transverse shortening induced by compression. The second short stage, which embraces the Pliocene–Quaternary and occasionally the end of the Miocene, differs in general, though differentiated in the value and intensification of vertical movements, when the height of mountains increases by 2–3 times. Elevations are spread over certain platform territories and even frameworks of rift zones. This is related not so much to the intensity of compression and shortening as to the compositional transformation of the upper mantle and the lower crust, leading to their decompaction. Comparison with the Hercynian and Caledonian orogenic stages shows that the second phase, predetermined by widespread collision, reflects a more important geodynamic event expressed in a change of the global plate interaction system and its deep-seated sources.

The subject of this study is strike-slip fault zones, where temporal variations of accumulation in strike-slip deformation complicate the standard process of deformation accumulation and release during strong earthquakes. These temporal variations are expressed in the El Ghab segment of the Dead Sea Transform zone (DST, Eastern Mediterranean) and in the Talas-Fergana fault zone (Central Asia). According to Global Positioning System (GPS) data, the strike-slip deformations within these zones are not now accumulating or are accumulating at a rate that is significantly less than their average rate during the Holocene and Quaternary or the Pliocene–Quaternary. Simultaneously, weak transverse shortening has been measured in both zones by GPS. In both of these zones, strong earthquakes have not registered within the XX century, yet epochs of intensified seismicity (strong earthquakes) took place throughout history. In the southern and central parts of the El Ghab zone, there is evidence of 30 strong historical earthquakes of Ms ≥ 5.7; however, no instrumental earthquakes of Ms ≥ 5 have been identified. The temporal distribution of seismic energy released by these earthquakes demonstrates a 350 ± 50-year cycle. Values for the seismic energies released during the peak phases of these cycles are approximated by a sinusoid that suggests the possibility of a ≥1800-year cycle (“hyper-cycle”), which began around the 3rd century, reached its maximum in the 12th century, and has continued until now. A combination of geological, archaeoseismological, and geodetic data show that the rate of sinistral strike-slip deformation varied in the fault zone, probably in conformity with the variation of seismicity during the “hyper-cycle.” In the Talas-Fergana fault zone, trenching and 14C dating that was correlated with right lateral offsets, gave a possible preliminary estimate of the average rates of the Late Holocene strike slip of about 10 mm per year, with a decrease in the SE direction to 4 mm–4.5 mm per year. These studies also showed that the slip in the Talas-Fergana fault zone was realized mainly during strong earthquakes. New trenching and 14C dating of paleoearthquake records identified the epoch of seismicity intensification dating to the XIV–XVII centuries. These paleoearthquakes could produce a total dextral slip at several meters. Therefore, consideration of these epochs was necessary to determine a calculated average slip rate during the Late Holocene. The main shock and the strongest aftershocks of the Altai earthquake of September 27, 2003, with Ms = 7.0 demonstrated a strike-slip focal mechanism with an NW-trending plane of the right lateral slip. An approximately 65 km-long NW-trending seismic rupture with a right lateral slip of up to 2 m, formed during the earthquake. The aftershock activity significantly decreased in 2004–2005 when reverse and rarer normal focal mechanisms became dominant. In the Palmyrides and the southern Aleppo block (NW Syria), strong earthquakes in 1994 (Mw = 5.3) and 1996 (Mw = 5.5) had strike-slip focal mechanisms, while only weak (magnitudes 1.1 to 3.3) earthquakes occurred in 2009–2011; the overwhelming majority of these weak earthquakes had normal and reverse mechanisms. In all of the cases mentioned above, strike-slip deformation was expressed only or mainly during strong earthquakes. At other times, the rate of its accumulation was small and the dominant stress conditions led to transverse shortening, rarely resulting in local lengthening of the tectonic zone. These variations are caused by the tectonic peculiarities of these zones. The sinistral component of the deformation is related to the shift of the Arabian Plate relative to the African one, but also the transverse component is related to the continental slope and is expressed by the Coastal range shortening that exists in the El Ghab segment zone. There is not only a dextral deformation component, but also a transverse component, expressed by shortening of the Fergana and Talas ranges existing in the Talas-Fergana fault zone. In both zones, the shortening component became appreciable or dominant when the strike-slip deformation rate decreased. Similar, but more local, relationships were expressed in the epicentral area of the 2003 Altai earthquake and in the Western Palmyrides.

Half a century ago, principles of the theory of lithosphere plate tectonics, or plate tectonics, were first formulated. Since then, the theory has become substantially more complicated and tectonic processes and phenomena have been identified that are not described by the theory. This relates to certain types of vertical movements, primarily to the newest uplifts that led to the formation of modern mountain systems. Comparison of geological processes (both those described by the theory of plate tectonics and those unexplained thus far) with data of the seismic tomography of the mantle has made it possible to outline a new tectonic model, according to which the source of observable tectonic manifestations is lateral flows of upper mantle matter, propagating from superplumes—flows of matter and energy rising from the mantle’s bottom. These lateral flows not only move lithospheric plates but also determine structural–substantial transformations of the lithosphere and the upper underlithospheric mantle, which lead to vertical movements and mounting building.

New data on location, height, and composition of terraces of the El-Kabir and Orontes rivers in Syria are represented. By combined use of paleontological, archaeological, paleomagnetic, and radio-isotopic methods, ages of these river terraces are estimated and they are correlated with the Euphrates River terraces. The age of the terraces is defined more precisely by evidence of synchronism of the El-Kabir alluvial terraces and the marine terraces of the Mediterranean coast. The average rates of incision during different time intervals were estimated in the studied valleys and their segments using relative height of the terraces. This gives the possibility of approximately estimating a rate of the Quaternary uplift in different tectonic provinces of Syria as well as rates of vertical movements on the Lattaqieh (the El-Kabir valley), Hama (the Orontes valley), and Euphrates (the Euphrates valley) faults. The rates of incision were usually small in the earlier stages of the valley formation and increased later. The Middle and Late Pleistocene rates of the valley incision reach ∼220–280 mm/ky in the El-Kabir valley (the Coastal Range-anticline), ∼80–130 mm/ky in the Orontes valley and the Euphrates upstream of the Assad Reservoir (the mobile platformal Aleppo Block), and ∼25–30 mm/ky in the Euphrates valley downstream of the Assad Reservoir (southwestern side of the Mesopotamian Foredeep).

Tectonic uplift producing recent mountain systems has spanned in the Alpine-Himalayan Belt the time interval from Oligocene to Recent (the last 30 - 35 Ma), being divided into two stages. During the first stage, local uplands, usually not higher than middle-elevated mountains, rose and their total area increased. During the second stage (the last 5 - 2 Ma) this process was accompanied by a total uplift of the greater part of the belt. As a result, the rate of vertical movements increased, the recent mountain systems were formed, and the coarse molasses accumulated in the adjacent basins. Uplift of the land surface resulting in formation of mountain topography is an isostatic reaction to decompaction of the upper spheres of the Solid Earth. Three factors of the decompaction are discussed in the paper. These are: I, collisional compression, resulting in deformational thickening of the Earth’s crust (folding, thrusting, etc.); II, partial replacing of the lithosphere mantle by the lower-dense asthenosphere material and, as a result, decompaction of the uppermost mantle; and III, retrograde metamorphism of high-metamorphosed rocks within the lower crust and near the crust-mantle boundary and, as a result, decompaction of these rocks. These processes were initiated or facilitated by the lateral asthenosphere flows. According to the seismic tomography data, the flows spread from the stationary developed zone of the rise of deep mantle material that is expressed in the recent structure as the Ethiopian-Afar super-plume. Reworking the 400 - 700-km deep transition layer of the mantle, the sub-lithosphere flows could be enriched in sources of aqueous fluids. The flows and their fluids initiated factors II and III of the tectonic uplift and caused softening and detachment of the lithosphere, facilitating deformational thickening of the Earth’s crust, i.e., the factor I. The latter produced uplands during the entire Oligocene-Quaternary development of the orogenic belt, while the factors II and III manifested themselves only during the second stage of mountain building. The detailed studies in the Central Tien Shan and the Greater Caucasus showed that the acceleration of uplift at the second stage was caused mainly by the factor II in the Central Tien Shan and the factor III in the Greater Caucasus.

It has been shown for particular seismic zones and the Alpine-Himalayan Orogenic Belt as a whole that in addition to Fedotov cycles, the long-period hypercycles of seismicity are distinguished. Long-period variations were revealed in Syria, in southern and central segments of the El-Ghab Fault Zone of the Dead Sea Transform (EG DST), and at the southwestern end of the East Anatolian Fault Zone (EAFZ). The EG DST demonstrates a ∼1800-year hypercycle with a maximum in the 3rd-7th and the 19th-20th centuries A.D. To reveal variations in seismicity in the entire central part of the orogenic belt, we have corrected evidence for historical earthquakes, taking into account the probability of missing events and the area of their regular recording domains. As a result, we displayed maximums of seismic energy release from the mid-17th to mid-20th century A.D.; from the mid-4th to the end of the 6th century; and in the 15th-13th centuries B.C. When interpreting hypercycles, it is important to keep in mind that variation of seismicity in EG DST correlates with variation of the rate of elastic deformation accumulation, probably reflecting variability of the stress-and-strain state in the region and of velocity of tectonic movements in active domains. After additional investigations, hypercycles could be taken into account for to refine the seismic hazard estimate.

From the end of the Eocene through the Pliocene, the Alpine-Himalayan Belt underwent collisional shortening induced by convergence of the Gondwana plates with the Eurasian Plate and varied in orientation from the north-northwestern to the northeastern directions. The collisional shortening was expressed in folding, thrusting of continental crustal tectonic sheets over one another, and closure of the residual basins of Neotethys and its backarc seas; it resulted in local thickening of the crust and its isostatic uplifting. As a rule, the uplifts were not higher than ∼1.5 km. In other words, before the Pliocene, the growth of local mountain edifices was caused by collisional shortening of the belt. Isostatic uplifting of the thickened crust was continued in the Pliocene and Quaternary even more intensely than before, but the general rise of the mountain systems was superposed on this process. The rise substantially exceeded in amplitude the contribution of the uplift caused by shortening and did not depend on the preceding Cenozoic history of either territory. Not only the mountain ridges but also most adjacent basins were involved in rising, which eventually led to the contemporary mountain topography of the belt. The spread of the hot and fluidenriched asthenosphere of the closed Tethys beneath the orogenic belt could have been a cause of such additional rising. The uplift was an isostatic reaction to decompaction of the lithospheric mantle partly replaced with asthenosphere and of the lower crust subject to retrograde metamorphism under the effect of cooled asthenospheric fluids. The deep transformations are also probably responsible for deepening of some basins in the Pliocene-Quaternary and more contrasting transverse segmentation of the belt.

Seismic tomographic data showing the mantle structure of the Ethiopian-Afar superplume and various segments of the Alpine-Himalayan Orogenic Belt and their relationships with the adjacent mega� structures of the Earth are presented. These data and their correlation with the geological evidence lead to the conclusion that lateral flows of mantle material are crucial for the evolution of the Tethys and its closure in the Cenozoic with transformation into an orogenic belt. The lateral flow of hot upper mantle asthenospheric matter spreading from the stationary superplume extending in the meridional direction (in presentday coor� dinates) was responsible for the accretion of the fragments torn away from Gondwana to Eurasia and for the development of subduction at the northeastern flank of the Tethys. The characteristic upper mantle structure of cold slabs passing into nearly horizontal lenses with elevated seismic wave velocity in the lowermost upper mantle is currently retained in the Indonesian segment of the orogenic belt. In the northwestern segments of this belt, a hot asthenospheric flow reached its northern margin after closure of the Tethys and onset of colli� sion, having reworked the former structure of the upper mantle and enriched it in aqueous fluids. The effect of this active asthenosphere on the lithosphere gave rise to intense Late Cenozoic deformation, magmatism, and eventually resulted in mountain building.

The Late Cenozoic geodynamics of the Alpine-Himalayan belt comprised the collision between continental-lithosphere plates and blocks and the effect of the Neo-Tethyan active residual asthenosphere, which reached the northern margin of the belt after the ocean had closed. From the late Eocene to the early Pliocene, strong deformation, lateral migrations of flaked plates, metamorphism, and magmatism (they all consolidated the crust) took place in the lithosphere with the participation of mobile asthenospheric components. In the Pliocene–Quaternary, the asthenosphere beneath the consolidated crust partly replaced the dense mantle lithosphere with remaining paleoocean mafic rocks, which subducted into the mantle. Phase transformations and deformations in the subducting metamafic slabs caused mantle earthquakes. The less compact metamafic rocks experienced metamorphic weakening under the effect of the asthenosphere and incorporated into the Earth’s crust. The upper-mantle and lower-crust weakening led to a drastic intensification of uplifting and the formation of mountain ranges. Recent volcanism is also attributed to the activity of the Neo-Tethyan asthenosphere.

New data on geology and 21 K–Ar dates of the Late Oligocene–Quaternary basalts in Syria, combined with analysis of the new and previous data are used to reconstruct the volcanic history and relations between it and tectonic events. Volcanism began at the end of Oligocene (26–24 Ma) and was concentrated in the Late Oligocene–Early Miocene along a N-trending band, which stretches from the Jebel Arab (Harrat Ash Shaam) up to Kurd Dagh and southern Turkey. Activity waned in the Middle Miocene (17–12 Ma), but was resumed in the same band in the Tortonian and increased in the Messinian and Early Pliocene (6.3–4 Ma), when volcanism spread to the Shin Plateau and its coastal extension. After a brief hiatus ∼ 4–3.5 Ma, volcanism became still more intensive and spread from the N-trending band to the east into the northern margin of the Mesopotamian Foredeep and to the west into the Dead Sea Transform zone. Additional eruptions continued into the Holocene. Volcanism lasted > 25 million years in the Jebel Arab Highland and > 15 million years in the Aleppo Plateau. The long duration of volcanism in the same parts of the moving Arabian plate and absence of records of one-way migration of the activity mean that the magmatic sources moved together with the plate, i.e., they were situated within the lithosphere mantle. Coincidence of the tectonic and volcanic stages of the Arabian plate development proves that volcanic activity depended on the geodynamic situation, caused by the plate motion. Situated within the lithosphere, magmatic sources within this transverse band were possibly caused by thermal and deforming influences of the asthenospheric lateral flow, moved laterally from the Ethiopia–Afar deep superplume.

Theoretical and applied implications of the study of active faults and their identification and parametrization are discussed. The term active fault is defined as a fault with displacements that occurred in the late Pleistocene and Holocene and are expected to resume in the future. The displaced young landforms, late Quaternary sediments, and man-made constructions are the main reference marks to recognize active faults and estimate their kinematics and intensity. Since the structural pattern and parameters of all active faults are referred to the same, geologically short time interval, they are important for the study of recent geodynamics and young tectogenesis on the global, regional, and local scales. The opportunities that are opened for such investigations are illustrated by verification of the real existence of the Okhotsk and Bering minor plates. With allowance for active faults, it is possible to make tectonic and geodynamic reconstructions of the past events more plausible. Natural hazards, primarily, earthquakes, are related to active faults. The geological and geomorphic assessment of the seismic potential of active fault zones is discussed with emphasis on the maximum possible magnitude of earthquakes (M max) estimated from the segmentation of the active zones, the length of particular segments (L), the empirical relationships M max/L for strong recent earthquakes, as well as the resumption periods of strong earthquakes and measurement of particular seismogenic offsets by trenching and other techniques, including archeoseismological methods. A question is posed about possible perennial variations in the stress-and-strain state of active zones, which are expressed on the scale of large seismoactive regions in oscillations of released seismic energy and should be taken into account by assessment of the seismic hazard.

In order to provide new data on the neotectonics and geodynamic properties of western Syria, studies of marine terraces have been carried out. The most attention was paid to the lower terraces in the range of 3–5 to 30–35 m above sea level, because they have more complete distributions along the shore. The lower terraces were examined along the coastal area from Tartus to Latakia, and along the carbonate cliff on Arwad Island. Seven 230 Th/U dates for these terraces are in the range of 85–130 ka, suggesting the age interval of the last interglacial (MIS 5). New dates on the lower terraces provide a basis for stratigraphical and geomorphological interpretation as well as neotectonic reconstruction. According to the geomorphological data and lithological composition of those terraces, two main uplifted blocks can be established. One coincides with the Latakia block, and another corresponds to the western margin of the Banias volcanic plateau. These blocks are divided by a subsided structure corresponding to the Nahr el Kebir graben. The amplitude of neotectonic uplifting in the Latakia and Banias blocks reaches 15–20 m for the Late Pleistocene.

The St. Simeon Fault is 80 km long and stretches from the eastern side of the Al Ghab Depression to the north–east; it links the structures of the Levant and East-Anatolian active zones. Left-lateral strike-slip displacements and deformations of landforms cut by the fault have been recorded. The Sim'an Ridge is located between two branches of the fault and displaced by 1.2 km, overlapping a young depression. As the terminations of these branches at the site of their overlapping converge northerly, the mechanism of structural scissors considerably enhances the lateral extrusion of the Sim'an Ridge. The St. Simeon Monastery, built by the Byzantine in the 5th century AD, is situated on the top of the Sim'an Ridge. The main church of the St. Simeon Monastery has a cruciform shape, and its eastern wing is deflected by 3–9° to the north. The existing architectural explanation of this phenomenon assumes initial designing of this bend by the builders and contains many contradictions. Upon our study of active faults, specific features and traces of seismic impacts on the monastery structures, we suggest an alternative, seismic explanation. Our scenario interprets the curvatures of the monastery structures as a consequence of distributed co-seismic or post-seismic deformations in the intra-fault block delimited by the branches of the St. Simeon Fault.

The Ming-Kush-Kokomeren Zone in the Middle Tien Shan is a transpressional structural unit, i.e., a longitudinal recent faultline depression, where manifestations of transverse shortening (intense folding, reverse and thrust faulting) are combined with left-lateral offset along the same faults; the left-lateral offset is commensurable to vertical separation along reverse and thrust faults or it even exceeds the latter. The complicated deformation within this zone has developed most intensely since the late Pliocene and reached a peak in the Pleistocene. However, the origin of this structural unit was at the onset of neotectonic stage, as evidenced from the Oligocene-lower Miocene conglomerate unit, which was formed as a product of the destruction of reactivated Hercynian thrust faults and nappes in the southern wall of the zone. The conglomerate filled a narrow ramp valley that formed in front of thrusts, probably due to the strike-slip offsets along boundary faults. Similar transpressional linear zones-Tessyk-Sary-Bulak, Uzunbulak-Oy-Kain, Kara-Kol, and Chong-Kemin (Kemin-Chilik)-are known in the Middle Tien Shan.

The validity of some data in Karakhanian et al. [Karakhanian, A., Djrbashian, R., Trifonov V., Philip H., Arakelian S., Avagian, A., 2002. Holocene–historical volcanism and active faults as natural risk factor for Armenia and adjacent countries. Journal of Volcanology and Geothermal Research, 113, 1, 319–344; Karakhanian, A., Jrbashyan, R., Trifonov, V., Philip, H., Arakelian, S., Avagyan, A., Baghdassaryan, H., Davtian, V., Ghoukassyan, Yu., 2003. Volcanic hazards in the region of the Armenian nuclear power plant. Journal of Volcanology and Geothermal Research, 126/1–2, 31–62] that are revisited by R. Haroutiunian is considered. A conclusion is made that the revisions suggested by Haroutiunian concern unessential parts of the content of work by Karakhanian et al. [Karakhanian, A., Djrbashian, R., Trifonov V., Philip H., Arakelian S., Avagian, A., 2002. Holocene–historical volcanism and active faults as natural risk factor for Armenia and adjacent countries. Journal of Volcanology and Geothermal Research, 113, 1, 319–344; Karakhanian, A., Jrbashyan, R., Trifonov, V., Philip, H., Arakelian, S., Avagyan, A., Baghdassaryan, H., Davtian, V., Ghoukassyan, Yu., 2003. Volcanic hazards in the region of the Armenian nuclear power plant. Journal of Volcanology and Geothermal Research, 126/1–2, 31–62]. This article presents new evidence and re-proves the earlier conclusions that are disputed or revised by R. Haroutiunian.

The neotectonic map of Syria, 1:500,000, was compiled by the authors in 2003–2004. The map shows tectonic features formed or continued to develop during the Neogene and Quaternary in Syria and adjacent territories, including the Mediterranean realm. The neotectonic structure of the region was formed as a result of three phases of deformation. During the Early Miocene first phase, the Arabian plate moved along the Dead Sea–Jordan segments of the Levant (Dead Sea) transform fault zone, Roum fault and its continuation in the continental slope of the Mediterranean. The chain of the coastal anticlines in the “Arabian” side of the transform zone and the Lattaqie oblique (sinistral-thrust) boundary fault zone in the north were formed under the NNW-trending compression. The Lattaqie zone continued by the Cyprus arc in the west and by the Taurus (Bitlis) thrust in the east and further by the Main Thrust of the Zagros. After “quiet” (for Syria) epoch of the Middle Miocene when the Arabian plate moved to the NE, during the Late Miocene second phase of deformation, the Arabian plate moved again to the NNW along the same transform boundary. But a part of the Late Miocene plate motion (up to 20 km) resulted by shortening in the Anti-Leban–Palmyride fold-thrust belt that separated the Aleppo block from the main part of the Arabian plate. During the Pliocene–Quaternary third phase of deformation, the recent structural pattern of the Levant zone was formed in Lebanon and the northwestern Syria. At the same time, the Serghaya and smaller sinistral faults branched out the Levant zone and the system of the W–E-trending convex to the south dextral faults ruptured the Palmyrides and the stable part of the Arabian plate. The total Pliocene–Quaternary sinistral offset on the young Levant zone segments and the associated faults has reached 35–40 km, like on the Dead Sea–Jordan segments of the Levant fault zone. The faults, demonstrating the Pliocene–Quaternary activity are still active now and represent the main seismic zones in Syria. Offsets on them are mostly a cumulative effect of strong earthquakes.

The database and map of active faults of Eurasia, 1:5,000,000, have been compiled according to the ILP Project II-2 “World Map of Major Active Faults.” The map shows the complicated distribution of active faulting. The major faults group in broad mobile belts between relatively weakly faulted parts of the main plates. The faults form the plates, microplates and crustal blocks boundaries there and are accompanied by deformation of the boundary areas. Using active fault data for the seismic hazard assessment (estimation of maximum possible magnitudes of earthquakes in fault zones), it is necessary to take into account the total neotectonic activity of the territory and average rate and sense of motion on the fault. Because trenching gives a possibility to determine only vertical earthquake offset on a fault, it is necessary to make corrections for strike–slip faults to estimate the earthquake magnitude by using this parameter.

Active tectonic movements in the northwestern Zagros include right lateral slip at the rate of about 10 mm/a along the Main Recent Fault, which inherits the position of the Main Thrust, now inactive, and active thrusting and accompanying folding distributed between several zones southwest of the Main Recent Fault. In the southeastern Zagros (the Fars Province), there are several right lateral faults that extend N–S obliquely to the overall trend of the Zagros fault-and-fold belt. These may be either branches of the Main Recent Fault, or faults accommodating relative broadening of the outer Zagros in its southeastern segment. The Main Thrust in the southeastern Zagros also remains inactive. The Ipak, North Tehran, and Mosha fault zones and several minor structures in the eastern Alborz form the E–W-trending active fault system with combined reverse and left lateral slip. On the Ipak and Mosha zones, lateral movements with the late Quaternary mean rate exceeding 1 mm/a dominate over vertical fault movements. Together with right lateral faults stretching northeast of Zagros, the faults of the Alborz may accommodate east-directed motion of the Iranian microplate.

Active faulting, a source of seismic disasters and ground deformation, may be also accompanied with the effects that can result in rapid or slow changes in the environment capable of affecting, either negatively or positively, living conditions of a man and in general evolution of animals and plants. Existing data still rare and uncertain show that these effects may be, first of all, specific fault-related landscapes and various geophysical and geochemical anomalies above and around active fault planes.

Active fault zones of Armenia, SE Turkey and NW Iran present a diverse set of interrelated natural hazards. Three regional case studies in this cross-border zone are examined to show how earthquakes interact with other hazards to increase the risk of natural disaster. In northern Armenia, a combination of several natural and man-made phenomena (earthquakes, landslides and unstable dams with toxic wastes) along the Pambak-Sevan-Sunik fault (PSSF) zone lowers from 0.4 to 0.2–0.3g the maximum permissible level (MPL) of seismic hazard that may induce disastrous destruction and loss of life in the adjacent Vanadzor depression. In the Ararat depression, a large active fault-bounded pull-apart basin at the junction of borders of Armenia, Turkey, Iran and Azerbaijan, an earthquake in 1840 was accompanied by an eruption of Ararat Volcano, lahars, landslides, floods, soil subsidence and liquefaction. The case study demonstrates that natural hazards that are secondary with respect to earthquakes may considerably increase the damage and the casualties and increase the risk associated with the seismic impact. The North Tabriz–Gailatu fault system poses a high seismic hazard to the border areas of NW Iran, eastern Turkey, Nakhichevan (Azerbaijan) and southern Armenia. Right-lateral strike–slip motions along the North Tabriz fault have given rise to strong earthquakes, which threaten the city of Tabriz with its population of 1.2 million. The examples illustrate how the concentration of natural hazards in active fault zones increases the risk associated with strong earthquakes in Armenia, eastern Turkey and NW Iran. This generally occurs across the junctions of international borders. Hence, the transboundary character of active faults requires transboundary cooperation in the study and mitigation of the natural risk.

We address volcanic hazards in the region of the Armenian Nuclear Power Plant and discuss the assessment of these hazards conducted in the framework of the International Atomic Energy Agency (IAEA) programs in 1994–1995. An important problem of volcanic hazard assessment is posed by assumptions that the apparent absence of recent volcanic activity in Armenia means that future eruptions in the vicinity of the site are impossible. We present new historical, archaeological, and field data, as well as records of the volcanic activity based on radiocarbon, fission-track, K/Ar and plateau-age determinations. This new evidence attests to volcanism in Armenia and adjacent areas during Holocene and historical time. Volcanic activity is demonstrated for Tskhouk-Karckar, Porak, Vaiyots-Sar, Smbatassar, Gegham Ridge and Ararat volcanoes. Volcanic eruptions occurred on Ararat at distances of 27 and 52 km from the plant site in 2500–2400 BC and in 1840 AD, respectively. New information permits a re-assessment of the volcanic hazards at a level higher than in the 1994–1995 studies.

Examples of Holocene-historical volcanism in the territory of Armenia and adjacent areas of Eastern Anatolia and Western Iran are discussed. Holocene-historical activity is proved for the volcanoes of Tskhouk–Karckar, Porak, Vaiyots-Sar, Smbatassar and Ararat. Based on the analysis of remote sensing data, field work, and historical and archeological information, it is demonstrated that there was a considerable number of cases of volcanic activity in Armenia and adjacent regions of Turkey, Syria and Iran during the historical period. The Holocene volcanic centers are situated within pull-apart basin structures and controlled by active faults. Situated in an area prone to many types of natural hazards, Armenia and adjacent countries face high natural risk. The evidence presented shows that volcanic hazard also contributes to the natural risk for these countries.

A part of the Alpine–Himalayan orogenic belt is studied, limited by 30–104°E and by 26–46°N to the west of 64°E and 26–56°N to the east of 64°E. A technique is proposed to calculate the field of the recent (Late Pleistocene and Holocene) deformation rate tensors in the upper crust (15 to 20 km) by active fault data. A hydrodynamic model of the medium is used for the calculation. Monotonous fault segments as long as 10–15 km are taken as the elementary cells of the medium. The cell square (the length multiplied by the depth) multiplied by the displacement vector magnitude, gives the geometric moment. Similar components of the local tensors of the geometric moments are summarized within the windows into which the region is divided. Finally, parameters of the axes of principal rates of deformation are calculated, and their directions and magnitudes are mapped. This tectonic deformation is compared with the seismotectonic one calculated by focal mechanisms of earthquakes. The compiled maps show: a concentration of high deformation rates in the plate boundary zones (especially in front of the southern plate syntaxes) and a smaller concentration in some microplate boundary zones; a predominance of the N–S-trending shortening and of strike-slip type of deformation. The rates of shortening and lengthening are usually almost equal to each other and differ essentially (the shortening rate is higher than the lengthening) only in specific sites. These are areas of intense recent detachment or late Quaternary volcanism. It seems that the double-axis lengthening (extension) is suitable for these processes.

The Syunik rhombus-like structure in the Khanarassar active dextral fault zone of Armenia is a typical pull-apart basin, formed between terminal parts of two adjacent en echelon fault segments. Some component of subsidence associated with the faults of the structure is found between the en echelon segments; nevertheless, the dextral component continues to be predominant even on the boundaries of the pull-apart basin. The late Pleistocene and Holocene lava volcanoes of the basin are also associated with those faults that have a component of extension. The relative ages of fault displacements and volcanic eruptions have been identified by the mutual correlation of lavas, moraines and topographic features and by archaeological and radiocarbon dating. According to the interpretation of rupturing and volcanism, major earthquakes and volcanic eruptions appear inter-related and three pulses of such activity during the earlier and middle Holocene have been identified.

The epicentre of the Roermond earthquake is located near the western boundary fault of the Roer valley trough, one of the deepest and the most active in the Quaternary part of the Lower Rhine graben. The Late Pleistocene and Holocene activity of the trough is manifested by offsets of the main (Mindel) and the lower (Riss and Late Pleistocene) terraces along the boundary faults. Surface fractures have been observed in an area of more than 50 km2: 2.5–3.5 km to the north of the town of Roermond, at 0.8 km to the south of the village of Herkenbosch and in the southeastern part of the village of Montfort. Three types of ruptures were differentiated: scarps up to 50 cm high along open fractures near the Maas River; open fractures (continued by scarps in some places) and open fractures with a liquefaction of the Quaternary alluvium sands. The last type is predominant. The location of the ruptures depends on the landscape and water-table of the region. While they could be produced solely by hydraulic shock during the earthquake (increased by the wet spring season), the majority of the ruptures strike N50°W ± 10°, i.e. parallel to the main trough faults, or N55°E ± 10°, along ‘neotectonic lines’, parallel to the Maas valley and deduced from space imagery. Thus, the ruptures could be the secondary surficial effect of the earthquake, linked indirectly with the active tectonics of the region.

The tectonic significance of the Erzincan earthquake of 13 March, 1992 in Eastern Turkey is discussed. The intersection of the North Anatolian and The East Anatolian strike-slip fault zones has resulted in formation of the Erzincan pull-apart basin and new seismically active fault branches on its northeastern side. Local concentrations of surface ruptures strike along the most active branches of the North Anatolian fault zone (N300W) for 62 km. They are usually open fractures with northeastern sides uplifted up to 20 cm and rarely with dextral offset up to 10 cm. These secondary ruptures manifest indirectly oblique seismic fault displacement corresponding to the Late Quaternary motion on the fault zone, although at the surface the dextral component has been suppressed relative to the vertical one.