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Horasan-Narman earthquake and its aftershock (b). (c) Focal mechanism of the 18 September 1984 earthquake, and (d) of the 18 October 1984 earthquake.
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The 1924 Pasinler & 1983 Horasan-Narman earthquakes which struck the Erzurum region occurred on the NE–SW-trending Horasan fault zone about 60 km east of Erzurum basin. The inversion of teleseismic seismograms, the aftershock pattern and the surface faulting of the 30 October 1983 (Ms = 6.8) Horasan-Narman earthquake indicate that it had dominantly...
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... of teleseismic body waves. Station weights were assigned according to ratios of the amplitudes of the P and SH waves. Based on the waveform inversion of long-period data, our best estimates for the source parameters of these four shocks are given in Table 1. The best fits between the observed and the theoretical P and SH-waves are shown in Fig. 3(a,b,c,d). The elongation of isoseismal curves, the aftershock distribution and the field observations (O È zguÈ l et al., 1983) suggest that the nodal plane striking NE±SW and dipping NW is the fault plane of the mainshock. However, this solution is inconsistent with the ISC epicentral location, probably due to error caused by the ...
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... stress changes induced by Turkish EQs . H. Eyidogan et al. nodal plane is the fault plane for the aftershock of 30 October 1983 and that the rupture process continued to the NE. The focal mechanism of the 18 September 1984 event (Fig. 3) shows leftlateral strike-slip faulting with a small thrust component on a NE-trending nodal plane. The 18 September 1984 event has a very similar focal mechanism to those of the 30 October 1983 mainshock and its first major aftershock, and a location far from the northern edge of the Horasan fault. The mechanism obtained for the ...
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... faulting with a small thrust component on a NE-trending nodal plane. The 18 September 1984 event has a very similar focal mechanism to those of the 30 October 1983 mainshock and its first major aftershock, and a location far from the northern edge of the Horasan fault. The mechanism obtained for the earthquake of 18 October 1984 is given in Fig. 3(d) and shows thrust faulting with a small left-lateral strike-slip component. This event displays a distinct character with an offset in its location and thrust faulting striking in almost in E±W ...
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... relative to the recurrence period (90 years) from the statistical calculations for a M s = 6.8 ( Alptekin et al., 1992). Macroseismic observations (Ambraseys, 1988) (Fig. 2) and our positive stress interaction assumption, led us to define the location of the most probable fault that slipped during the 1924 event (Fig. 3) within the stress field of the 1983 earthquake. Figure 5 shows the Coulomb stress change pattern caused by the 1924 earthquake. The fault that slips in the 1983 event, lies where stress is increased by 1 bar or more, parallel to optimum left-lateral slip planes (white lines). Coulomb stress change along the 1983 earthquake fault 6.5 km ...
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... observations of these aftershocks indicate that the epicentres of the aftershocks should be located about 10 km south of their present position (Eyidogan, 1985). In that case, the correlation between the positive stress field and the 1984 aftershocks would be much more clear. Since the 18 October 1984 event had a mainly thrust movement (Fig. 3), we have also calculated the stress field on optimally orientated thrust faults as indicated above (Fig. 7b). The 18 October 1984 event lies at the edge of 0.1 bar contour line implying that it was loaded by at least 0.1 bar due to preceding events. Most of the aftershocks also correlate with positive stress changes. Some parts of the ...
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Citations
... The ADF is the NW margin of the cell and the focal mechanism solutions are available for its SW end (Fig. 10.13B). The focal mechanism solutions of the Oct. 18, 1984 earthquake (Mw ¼ 5.6) (Eyido gan et al., 1999) and Oct. 30, 1983 earthquake (Mw ¼ 5.5) (ISC, HRVD) indicate NEeSW trending left lateral strike-slip faulting. The epicenters of these earthquakes are near segments ADF-5a, 5, and 6 around south of Be gendik (Fig. 10.13B). ...
... 10.1 and 10.14). Although the focal mechanism solution of this earthquake indicates left lateral strike-slip faulting (Toksö z et al., 1983;Eyido gan et al., 1999), the surface rupture determinations of Barka et al. (1983) andÖ zgü l et al. (1983) describe typical distributed internal deformation of a rhomboidal cell, such as opening fractures and right lateral faulting that accompanied the main left lateral strike-slip faulting. ...
The Turkish–Iranian Plateau is located on the hinterland of the Bitlis–Zagros suture zone and contains systematic active strike-slip fault patterns forming several rhomboidal cells. The reevaluation of marginal strike-slip faults of the cells and focal mechanism solutions of earthquakes together with global positioning satellite data pointed out that the rhomboidal cells might partially eliminate the postcollisional north–south contraction created by the convergence between the Arabian and Eurasian plates.
A total of 17 rhomboidal cells have been described and the segmentations of 41 marginal strike-slip faults were determined using high-resolution satellite images. The Ahar, Urmiye, Van, and Nahçivan cells are among the largest in area and contain nearly all features of an ideal rhomboidal cell. There is a close relation between the location of volcanic centers and the east and west corners of the cells where the left and right lateral nonparallel strike-slip faults create an escape wedge.
Analysis of the rhomboidal cells in the Turkish–Iranian Plateau reveals the region-wide brittle shear zones. The southwest margins of Kiğı, Karlıova, Muş, Van, and Urmiye cells are located on a single line and forming the northwest–southeast trending, 63- km-long, right lateral shear zone that is connected to the main recent fault with a releasing overstep in the Piranşehr. This region-wide structure, the southeast Anatolian–Zagros fault zone, probably eliminates important amounts of north–south convergence between the Arabian and Eurasian plates. The relation between this structure and the right lateral north Anatolian fault zone is an overstep in which the Kiğı, Karlıova, and Muş cells are located.
... Eastern Anatolia is a province characterized by a N-S compressional tectonic regime Horasan-Norman (Ms= 6.8), the June 6, 1986 Doğanşehir (Ms=5.6) and the March 2, 2017, Adıyaman-Samsat (Mw 5.5) (Canıtez and Üçer, 1967;McKenzie, 1972;Barka et al, 1983;Ambraseys, 1988;Taymaz et al., 1991;Toksöz et al., 1983;Eyidoğan et al., 1999) earthquakes. The East Anatolian Fault was first described by Allen (1969) who showed that it forms part of the transform boundary between the Anatolian and Eurasian plates, and the African and Arabian plates. ...
Summary:
The transform Arabian/Anatolian plate boundary is at the origin of active tectonic structure elements that initiate large and destructive earthquakes. The aim of this thesis is to improve our knowledge and understanding of the fault behavior and deformation remarks by analyzing surface deformation along the East Anatolian Fault (EAF) that is a morphologically very distinct and seismically active left-lateral strike-slip fault that extends for ~400 km forming the Arabian/Anatolian plate boundary in southeastern Turkey. Together with its conjugate the North Anatolian Fault (NAF), the EAF helps accommodate westward escape of the Anatolian plate from the Arabian/Eurasian collision zone. In this thesis, we study morphotectonics and tectonic activity of the EAF and its splay Adıyman Fault (AdF) using the most important tectonic geomorphology indexes and analyzing different satellite images within the Arabian/Anatolian plates deformation zone. The core parts of the thesis focus on the study of morphotectonic indexes along the EAF, examining the geological offsets along the Erkenek Segment of the EAF through analyzing ASTER satellite images, relative tectonic activity assessment of the AdF, and geological and tectonic mapping along the AdF using Landsat 8 satellite images. The methods used in this thesis work are divided into two parts; the first part describes the importance of the tectonic geomorphology applications as a very useful tool to examine the interplay between tectonic and surface processes that shape the landscape in regions of active deformation and at time scales ranging from days to millions of years. It also presents a review of the most effective morphotectonic indexes (e.g., Mountain front Sinuosity; valley-floor with to valley floor-height; Hypsometric analysis) that are used to evaluate the tectonic activity along the study region. The second section gives a brief view about the application of remote sensing techniques in geology and tectonics and how the techniques have a great power to assess the different tectonic features and trace the structural elements along any active zone. Also, it presents the characteristics of the different satellite data (ASTER and Landsat 8 (OLI)) with the revision of the different method that we used in this study (e.g. Band Ratio Composite and Minimum Noise Fraction Analysis). The morphotectonic features along the East Anatolian Fault (EAF) are examined for the first time to provide insights into the nature of landscape development and better understanding of variations in tectonic activity and fault evolution. Several geomorphic indices, namely mountain front sinuosity, valley-width to valley-height ratio, stream length-gradient index, basin asymmetry factor, drainage density, and hypsometric analysis are obtained from digital elevation models. We show that mountain front sinuosity varies from 1.01 to 1.46 on five segments. The mean ratio of valley-width to valley-height along the five segments ranges from 0.11 to 1.32, which is well correlated with the mountain front sinuosity values. The stream length-gradient index values are between from 50 and 350 along the studied segments. Analysis of the basin asymmetry factor of 18 catchments gives values from 1.88 to 26.25 are examined along the study fault zone and we present the basin asymmetry factor with values from 1.88 to 26.25. The drainage density values of the studied catchments range from 3.5 to 5.6. Finally, the hypsometric analysis index of the 18 catchments records high, intermediate, and low relative tectonic activity. The results show that all geomorphic indices are remarkably uniform along the entire fault length, thus implying that its development was essentially coeval along its length, and supporting the view that the present-day Arabian/Anatolian plate boundary (delimited by the EAF) jumped eastwards from the Malatya-Ovacik Fault Zone at ~3 Ma. This is in a good agreement with the nearly uniform geological offsets and the present-day slip rate of ~10 mm/yr along the entire fault as determined by GPS measurements. The Erkenek Segment is one of the most active and prominent splays of the East Anatolian Fault. To reveal any potential geological offset geology along the AdF is refined by remote sensing techniques. This is because, mapping the geology at high spatial resolution along this segment with conventional mapping techniques is highly challenging due to the complex tectonics and the abundant number of different lithological units of varying spatial extent. Therefore, in this study, we applied image spectral rationing techniques by using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data along the Erkenek Segment. Images created with band ratios with 1/3-1/9-3/9, 7/3-1/7-3/5 and 9/5-5/3-3/1 are found to be remarkably useful for detailed lithological mapping and hence detecting the geological offsets along this section of the fault. Thus, these ASTER band-ratio images can be used for the lithological mapping along the whole EAF and on other regions in the world with similar lithological and geomorphological conditions. Geomorphic indices that include mountain-front sinuosity, valley floor width-tovalley height ratio, catchment asymmetry factor, hypsometric integrals and curves, and drainage density are calculated to evaluate the relative tectonic activity along the Adıyaman fault. Each geomorphic index is classified into three classes and averaged to define an index for relative tectonic activity (RTA) to allow the Adıyaman Fault to be divided into categories of low, intermediate and high RTA. The results confirm that the Adıyaman Fault is an active fault with intermediate Quaternary tectonic activity, suggesting that it is of minor importance in accommodating plate boundary deformation, consistent with recent crustal motions determined by GPS studies. Nevertheless, it is worthwhile to note that the Adıyaman Fault still poses a significant seismic hazard for the region despite its relatively lower tectonic activity. Independent Component Analysis (PCA and ICA) and Minimum Noise Fraction Analysis (MNFA) techniques of the Landsat 8 are applied to study the Adıyaman Fault. It is shown that the lithologic units, fault patterns, and morphological and structural features can be mapped highly accurately by using spectral-matching techniques in regions where rocks are well exposed. Inspection of all possible band combinations indicates that PCA 134 and 231, and ICA 132 band combinations give the best false-color composite images for identifying the rock units and contacts. Analysis of MNFA band combinations shows that MNFA 521 band combination also is robust for discriminating the rock units particularly Quaternary clastic units (colluvium/alluvium). MNFA band 1 alone provides the best image to trace the tectonic and structural elements in the study area. The new up-to-date lithologic map of the Adıyaman Fault that we produce upon to the interpretation of processed OLI images reveals several river channels offset and beheaded by the Adıyaman Fault, verifying its Quaternary activity. This study demonstrates that, when used with the OLI data, the PCA, ICA, and MNFA are very powerful for lithological and structural mapping in actively deforming tectonic zones, and hence can be applied to other regions elsewhere in the world where the climate is arid to semi-arid, and the vegetation cover is scarce. In generally this study presents the help of the tectonic geomorphology and remote sensing applications to evaluate the tectonic activities of a major plate boundary fault and a minor fault within the Arabian/Anatolian deformation zone. Improving our tectonic understanding of the active regions requires accurate tectonic measurements and data analysis. It so important to link the morphotectonic analysis with the different surface displacements, slip rates, and major seismic events in order to create a complete scenario about the deformation story of the active regions. Also, the new developed remote sensing methods with high-resolution images are required to go deep and gain the most benefits of applying these techniques for geology and tectonics purposes.
... Soma 6.9 30 Nalbant et al., (1998Nalbant et al., ( ) 13.09.1924 Pasinler 6.8 15 Eyidoğan et al., (1999Eyidoğan et al., ( ) 20.11.1924 Altıntaş 6.0 10 Nalbant et al., (1998) Acharya (1979Acharya ( ) 27.03.1975 Saros 6.6 20 Nalbant et al., (1998Nalbant et al., ( ) 06.09.1975 ...
Many practical problems encountered in quantitative oriented disciplines entail finding the best approximate solution to an over determined system of linear equations. In this study, it is investigated the usage of different regression methods as a theoretical, practical and correct estimation tool in order to obtain the best empirical relationship between surface wave magnitude and rupture length for Turkey earthquakes. For this purpose, a detailed comparison is made among four different regression norms: (1) Least Squares, (2) Least Sum of Absolute Deviations, (3) Total Least Squares or Orthogonal and, (4) Robust Regressions. In order to assess the quality of the fit in a linear regression and to select the best empirical relationship for data sets, the correlation coefficient as a quite simple and very practicable tool is used.
A list of all earthquakes where the surface wave magnitude (Ms) and surface rupture length (L) are available is compiled. In order to estimate the empirical relationships between these parameters for Turkey earthquakes, log-linear fit is used and following equations are derived from different norms:
for L2 Norm regression (R2=0.71),
for L1 Norm regression (R2=0.92),
for Robust regression (R2=0.75),
for Orthogonal regression (R2=0.68),
Consequently, the empirical equation given by the Least Sum of Absolute Deviations regression as with a strong correlation coefficient (R2=0.92) can be thought as more suitable and more reliable for Turkey earthquakes. Also, local differences in rupture length for a given magnitude can be interpreted in terms of local variation in geologic and seismic efficiencies. Furthermore, this result suggests that seismic efficiency in a region is dependent on rupture length or magnitude.
Resumen
Muchos problemas prácticos encontrados en las disciplinas de orientación cuantitativa implican encontrar la mejor solución aproximada para un sistema determinado de ecuaciones lineales. En este estudio se investiga el uso de diferentes métodos de regresión tanto teóricos como prácticos y la herramienta de estimación correcta con el fin de obtener la mejor relación empírica entre la magnitud de onda superficial y la ruptura de longitud para los terremotos en Turquía. Para este propósito se hace una comparación detallada a partir de cuatro normas diferentes de regresión: (1) mínimos cuadrados, (2) mínimas desviaciones absolutas, (3) mínimos cuadrados totales y (4) regresiones robustas. Con el fin de evaluar la regresión lineal adecuada y seleccionar la mejor relación empírica de grupos de datos empíricos, la correlación de coeficiente es una herramienta simple y muy práctica. Se compiló una lista de todos los terremotos donde se cuenta con la magnitud de onda superficial (Ms) y la ruptura de longitud superficial (L). Con el fin de determinar las relaciones empíricas entre estos parámetros para los terremotos de Turquía, se utiliza la regresión lineal adecuada y las siguientes ecuaciones se derivan de diferentes reglas.
Ms = 1.02* LogL + 5.18, para la regresión normal L2 (R2=0.71),
Ms = 1.15* LogL + 4.98, para la regresión normal L1 (R2=0.92),
Ms = 1.04* LogL + 5.15, para la regresión robusta (R2=0.75),
Ms = 1.25* LogL + 4.86, para la regresión ortogonal (R2=0.68).
Por consiguiente, la ecuación empírica dada por la regresión de desviaciones mínimas absolutas es con un fuerte coeficiente de correlación (R2=0.92) que sería más apropiado y más confiable para los terremotos de Turquía. También, las diferencias locales en la ruptura de longitud para una magnitud dada puede ser interpretada en términos de eficiencia sísmica y geológica en la variación local. Además, el resultado sugiere que la eficiencia sísmicaen una región depende de la ruptura de longitud o de la magnitud.
... It ruptured the northern end of the Çobandede fault zone (Koçyiğit et al., 2001), which is a 4 to 6 km wide and a 130 km long dominantly northeast trending sinistral shear zone with conjugate northwest trending strike slip faults (Şengör et al., 1985; Barka et al., 1983). The recent destructive Horasan-Narman Earthquake (30 October 1983, M w 6.8) had ruptured the same fault zone south of the Şenkaya earthquake (Eyidoğan et al., 1999). The moment tensor solution of the Şenkaya earthquake indicates a strike slip source mechanism (Figures 3 and 4). ...
Source properties of small-to-moderate magnitude events in eastern Turkey were studied using high quality waveform data produced by the Eastern Turkey Seismic Experiment (ETSE). A data set of fault plane solutions was obtained for 134 earthquakes using the regional moment tensor inversion technique for 34 events with magnitude 3.7 and above, and first motion analysis for 115 earthquakes with magnitude 3.0 and higher (for 15 events both techniques were used). Most of the events studied had strike slip mechanisms in agreement with nearby local fault structures. Reverse mechanisms were more scarce and were restricted to certain areas, such as in the eastern Anatolian plateau and southwest of the Karliova junction along the Arabian plate boundary. Our results indicate a difference in the deformational style east and west of the Karliova junction which results in internal deformation in the east and westward extrusion of the Anatolian plate with no or very little internal deformation in the west. Our results also suggest that in eastern Turkey, most of the collision is taken up by strike slip faults of varying types and sizes, suggesting that the northward convergence of Arabia is being accommodated by escape tectonics. Compressive features, such as thrust faulting, which were obviously the primary faulting during the earliest stages of continental collision, are still active but are of lesser importance.
On June 14, 2020, Mw 5.9 Kaynarpınar earthquake occurred in the easternmost part of the North Anatolian Fault Zone, along the Yedisu Seismic Gap near the Karlıova Triple Junction. Following the event, various agencies reported different epicenter locations. This issue and the complex fault pattern around the triple junction caused uncertainties about the ruptured fault and the rupture mechanism. To define the geometry of the ruptured fault, we (1) held a field survey within a week of the mainshock, (2) correlated our field data with the multitrack InSAR data, (3) relocated the epicenter of the mainshock, and its aftershocks, and (4) implemented moment tensor inversion analyses to the earthquakes larger than M 3.3. We defined a ~N70E-striking surface rupture and measured the average co-seismic dextral slip magnitude as ~16±1 cm in the field which is compatible with the horizontal displacement magnitude measured by InSAR (13-15 cm). Since no ~N70E-striking faults were reported in the existing active fault database, we examined the prominent geomorphological structures along the rupture area. We determined two dextral fault families along the eastern part of the Yedisu Seismic Gap; (1) NW-SE-striking faults of the North Anatolian Fault Zone, and (2) N70E-striking faults forming the Kaynarpınar-Yuvaklı Fault Zone. This fault zone, defined and named in this study, is a part of the N70E-striking faults of the Turkish-Iranian High Plateau and the North Anatolian Fault Zone. The fault zone must have carried some, if not most, of the dextral sense-of-slip in the easternmost part of the North Anatolian Fault Zone during the Quaternary.
On Friday, January 24, 2020 at 20.55:11 local time (17:55 UTC), an earthquake with a magnitude of Mw = 6.8 has occurred in Sivrice district of Elazığ (Eastern Turkey). Focal mechanism solution is consistent with pure left-lateral strike-slip faulting; the location of the epicenter and fault mechanism suggest deformation along the Pütürge segment of the East Anatolian Fault Zone. A 10-day fieldwork was carried out along the Pütürge segment to study surface deformation; the geometry of the surface rupture and other seismic geomorphological structures were mapped and studied in detail. The field data are also correlated with satellite images. This paper, therefore, presents classification of seismic geomorphological structures and discuss intimate relationship between fault geometry and stress field in the region. Seismic geomorphological deformation and related features of the Sivrice (Elazığ) earthquake are observed in the area between Gezin (Elazığ) and Ormaniçi (Pütürge) villages; they are classified into two as seismotectonic and seismo-gravitational features. Field observations confirm that seismo-gravitational structures develop along both Gezin-Sivrice–Doğanbağı and Doğanbağı–Çevrimtaş–Ilıncak–Koldere–Ormaniçi sections of the Pütürge segment, while surface rupture is mapped as seismotectonic structure only along the Doğanbağı–Çevrimtaş–Ilıncak–Koldere–Ormaniçi section. Small-scale landslides, rock falls, feather cracks along asphaltic roads, and laterally discontinues ground failure-related features are common seismo-gravitational structures that developed along the fault zone. In addition, small-scale lateral spreading and liquefaction structures are common especially in areas where fault-perpendicular streams meet the Karakaya Dam reservoir. The surface rupture is mapped as stepping and overlapping en échelon fractures along elongated pressure ridges between Çevrimtaş and Doğanbağ villages, to northwest of Ilıncak village, along 1.5-km-long pressure ridge between Topaluşağı and Doğanyol, across the elongated hill that developed on an alluvial fan to the northwest of Doğanyol and in the area between Koldere and Ormaniçi villages. Surface fractures deforming the pressure ridges are all aligned parallel to the long axes of the ridges and display reverse components that give rise to small-scale pop-up structures. Interferometric SAR (DInSAR) studies indicate a 10-cm uplift in the northwestern block of the fault and a 6-cm subsidence in the southeast block. The difference in vertical movements between two blocks of the fault is interpreted to suggest that at least 30-km-long section of the Pütürge segment in the area between southwest of Sivrice and Pütürge is broken during the main shock. Although the focal mechanism solution of the main shock gives pure left-lateral strike-slip faulting, there is no significant left-lateral displacement observed during the fieldwork. This can be explained by the following: (1) left-lateral strike-slip displacement was not able to reach the surface; (2) left-lateral torque movement of the fault around a vertical axis during the earthquake, (3) restraining bend nature of the Pütürge segment, or (4) the presence of Pütürge metamorphics along the fault strike. It is also important to note that along most part of the Pütürge segment where surface rupture is observed, talus, colluvial or alluvial fan sediments are exposed; unconsolidated and/or poorly consolidated nature of these sediments may also be counted as one of the main reason for not observing horizontal displacement on the surface. When we compare these surface deformations with the surface ruptures that occurred in the last 100 years in Turkey, we suggest that the formation of the surface deformations is variable depending on: (1) the fault type and the state of regional stress, (2) the magnitude of the earthquake, (3) the duration time of the earthquake and (4) the geomorphologic feature of landscape in relation to the lithologic and structural features of the rock units along the active fault zone.
Post-collisional magmatism may be generated by extensive crustal melting in Tibet-type collisional environments or by falling out of slabs from under giant subduction-accretion complexes in Turkic-type collisional orogens giving rise to decompression melting of the asthenospheric mantle replacing the removed oceanic lithosphere. In Turkic-type post-collisional magmatism, the magmatic products are dominantly alkalic to peralkalic and greatly resemble those of extensional regions giving rise to much confusion especially in interpreting old collisional orogenic belts. Such magmatic regions are also host to a variety of economically valuable ore deposits, including gold. One place in the world where today active, Turkic-type post-collisional magmatism is present is the eastern Anatolian high plateau, produced after the terminal Arabia/Eurasia collision in the late Miocene. The plateau is mostly underlain by the late Cretaceous to Oligocene East Anatolian Accretionary Complex, which formed south of the Rhodope-Pontide magmatic arc. This subduction-accretion complex has been further shortening since the collision, but it has also since been domed and became almost entirely covered by at least 15,000 km(3) of volcanic rocks. The volcanic rocks are calc-alkalic in the north, transitional in the middle, and alkalic in the south of the plateau. Where the crust is thinnest today (less than 38 km), the volcanics are derived almost entirely from an enriched mantle. The ages of the volcanics also become younger from north to south, from about 11 Ma to possibly 17th century AD. We interpret the origin of the magmatic rocks as the result of decompression melting of the asthenospheric mantle sucked towards the exposed base of the East Anatolian Accretionary Complex as the oceanic lithosphere beneath it fell out. The lower density of the hot asthospheric material was the cause of the doming. We believe that similar processes dominated the post-collisional tectonics of such vast Turkic-type orogens as the Altaids of Central Asia, the late Devonian-early Carboniferous Lachlan Belt in southeastern Australia, and the Pan-African collage of northeast Afro-Arabia. It is likely that Archaean collisions were dominated by Turkic-type post-collisional events rather than Tibetan ones that only became common in the Proterozoic. (C) 2008 Elsevier B.V. All rights reserved.
The earthquake,data from instrumental records in the last 40 years indicate the general seismicity of the earth. However, examining historical records is necessary to understand long-term seismicity. Catalogue studies about historical earthquakes in Turkey are limited. All these catalogues are on printed paper and a digital database has not yet been prepared. On the other hand, there is no common database for the focal mechanism solutions of the recent destructive earthquakes (Mw≥5.5) in the region. The present study aims to prepare,two new digital databases for earth scientists so that the earthquake parameters can be reached from a single source. The first one is ‘The Historical Earthquake Catalogue of Turkey’ which includes parameters,of the,earthquakes occurring between 2100 B.C. and 1963 A.D. This database contains approximately 2285 events and is presented as an electronic supplement. The second dataset, ‘The Focal Mechanism Solutions Catalogue of Turkey’, contains fault plane solution parameters,of the,destructive earthquakes occurring between,1938 and 2004. All available mechanism solutions of the destructive earthquakes were collected, although the global moment tensor solutions reported via the internet were not included in the present study. Key Words: Turkey, historical earthquakes, focal mechanism solutions, earthquake catalogue Türkiye Deprem Katalo¤u
The Pasinler Basin, in the 'East Anatolian Contractional Province', features a suite of geomorphological zones, visible in the field, air photographs and Landsat and Shuttle Radar Topography Mission (SRTM) digital elevation model imagery. These zones reflect past and current tectonically influenced processes. Relicts of the Erzurum-Kars Plateau representing Mio-Pliocene volcanism, associated with transtensional tectonics, have been modified by two stages of drainage development: an earlier, shallow valley network, which was modified following uplift and tilting to form the present system characterized by deep narrow valleys that supply alluvial fan complexes. These fans discharge onto the present, aggradation-dominated basin floor. Initial normal faulting induced massive slope failures on the basin's northern margin. This extensional phase within the basin was reversed by the Late Pleistocene, with thrust faults modifying and producing landforms, and affecting sediment sequences, along both its northern and southern margins. The shift from a transtensional regime, and the associated volcanism, to normal faulting in the Pliocene to Early Pleistocene, and then to the present regime of compression-induced thrusting appears to correspond to a regional tectonic shift resulting from the collision of the Eurasian and Arabian plates and the subsequent westwards movement of the Anatolian microplate.
