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&#x;nan Ulusoy Philippe Labazuy Erkan Aydar Orkun Ersoy Evren ubuku 《Journal of Volcanology and Geothermal Research》2008,174(4):269-283
Plio-Quaternary volcanism played an important role in the present physical state of Eastern Anatolia. Mount Nemrut, situated to the west of Lake Van is one of the main volcanic centers in the region, with a spectacular summit caldera 8.5 × 7 km in diameter. The most recent eruptions of the volcano were in 1441, 1597 and 1692. Nemrut Lake covers the western half of the caldera; it is a deep, half-bowl-shaped lake with a maximum depth of 176 m. Numerous eruption centers are exposed within the caldera as a consequence of magma–water interaction. Current activity of Nemrut caldera is revealed as hot springs, fumaroles and a small, hot lake.Self-potential and bathymetric surveys carried out in the caldera were used to characterize the structure of the caldera and the associated hydrothermal fluid circulation. In addition, analyses based on digital elevation models and satellite imagery were used to improve our knowledge about the structure of the caldera. According to SP results, the flanks of the volcano represent “the hydrogeologic zone”, whereas the intra-caldera region is an “active hydrothermal area” where the fluid circulation is controlled by structural discontinuities. There is also a northern fissure zone which exhibits hydrothermal signatures. Nemrut caldera collapsed piecemeal, with three main blocks. Stress controlling the collapse mechanism seems to be highly affected by the regional neotectonic regime. In addition to the historical activity, current hydrothermal and hydrogeologic conditions in the caldera, in which there is a large lake and shallow water table, increase the risk of the quiescent volcano. 相似文献
73.
We present the volcanic ash and tsunami record of the Minoan Late Bronze Age Eruption of Santorini (LBAES) in a distal setting in southwestern Turkey. In one of the drilled cores at the Letoon Hellenic antique site on Eşençay Delta, we encountered a 4 cm thick tephra deposit underlain by 46 cm thick tsunami-deposited sand (tsunamite), and an organic-rich layer that we 14C dated to 3295 ± 30 bp or 1633 bc. The relationship between Santorini distal volcanic ash and underlying tsunamite is described and interpreted. LBAES occurred in four main phases: (1) plinian; (2) phreatomagmatic; (3) phreatomagmatic with mudflows; and (4) ignimbritic flows and co-ignimbrite tephra falls. In this study, we aim to understand which eruptive phases generate distal ash during the Minoan eruptive sequence by examining the 3D surface morphology of ash formed by different fragmentation processes. To that end, we used numerous statistical multivariates, 3D fractal dimension of roughness, and a new textural parameter of surface area-3D/plotted area-2D to characterise the eruption dynamics. Based on ash surface morphologies and the calculated statistical parameters, we propose that that distal ash is represented by a single layer composed of well-mixed (coarse to fine) magmatic and phreatomagmatic ash. 相似文献
74.
Erkan Gökaşan Mustafa Ergin Mustafa Özyalvaç Halil İbrahim Sur Hüseyin Tur Tolga Görüm Timur Ustaömer Fatma Gül Batuk Hakan Alp Halim Birkan Ahmet Türker Erhan Gezgin Murat Özturan 《Geo-Marine Letters》2008,28(2):107-129
Seismic profiling, bathymetric and physical oceanographic data collected from the Çanakkale Strait revealed that the morphological evolution of the strait has been controlled by tectonic activity, and sediment erosion and deposition. Sediments in the strait have been sourced mostly by rivers draining the Biga Peninsula during lowstand periods. In highstand periods, by contrast, deposits in the strait were reworked by currents. The seafloor morphology of the Çanakkale Strait is also controlled by a sequence of factors ranging from tectonics to current erosion and deposition. Channel deposits overlying the basement are being eroded at the narrower, meandering central section of the strait (the Nara Passage) due to high current velocities. The eroded sediments are deposited in the relatively linear and wider, northern and southern sectors of the strait exposed to low current velocities. As a result, the high-energy areas are more deeply incised due to the erosion, whereas deposition elevates the seafloor in the areas exposed to lower current energy. Three strike-slip faults, which possibly relate to the activity of the North Anatolian Fault Zone, are responsible for the irregular shape of the strait and this, in turn, controls the current velocity along the strait. The high-energy conditions probably commenced with the latest invasion of Mediterranean waters some 12 ka b.p., and have continued as a two-layered current system to the present day. 相似文献
75.
Faulting, mass-wasting and deposition in an active dextral shear zone, the Gulf of Saros and the NE Aegean Sea, NW Turkey 总被引：1，自引：1，他引：0
Timur Ustaömer Erkan Gökaşan Hüseyin Tur Tolga Görüm Fatma Gül Batuk Doğan Kalafat Hakan Alp Berkan Ecevitoğlu Halim Birkan 《Geo-Marine Letters》2008,28(3):171-193
Structural, mass-wasting and sedimentation processes along an active dextral shear zone beneath the Gulf of Saros and the
NE Aegean Sea were investigated on the basis of new high-resolution swath bathymetric data and multi-channel seismics. A long
history of dextral shearing operating since the Pliocene culminated in the formation of a NE-SW-trending, ca. 800-m-deep basin
(the so-called inner basin) in this region, which is bordered by a broad shelf along its northern and eastern sides and a
narrow shelf at the southern side. The western extension of the North Anatolian Fault Zone (the Ganos Fault) cuts the eastern
shelf along a narrow deformation zone, and ends sharply at the toe of the slope, where the strain is taken up by two NE-SW-oriented
fault zones. These two fault zones cut the basin floor along its central axis and generate a new, Riedel-type pull-apart basin
(the so-called inner depression). According to the bathymetric and seismic data, these basin boundary fault zones are very
recent features. The northern boundary of the inner depression is a through-going fault comprising several NE-SW- and E-W-oriented,
overlapping fault segments. The southern boundary fault zone, on the other hand, consists of spectacular en-echelon fault
systems aligned in NE–SW and WNW–ESE directions. These en-echelon faults accommodate both dextral and vertical motions, thereby
generating block rotations along their horizontal axis. As the basin margins retreat, the basin widens continuously by mass-wasting
of the slopes of the inner basin. The mass-wasting, triggered by active tectonics, occurs by intense landsliding and channel
erosion. The eroded material is transported into the deep basin, where it is deposited in a series of deep-sea fans and slumps.
The high sedimentation rate is reflected in an over 1,500-m-thick basin fill which has accumulated in Pliocene–Quaternary
times. 相似文献
76.
Erkan Gökaşan Hüseyin Tur Mustafa Ergin Tolga Görüm Fatma Gül Batuk Nurcan Sağcı Timur Ustaömer Ozan Emem Hakan Alp 《Geo-Marine Letters》2010,30(2):113-131
Seismic and bathymetric data from the Çanakkale Strait and its extensions onto the shelves of the Marmara and Aegean seas indicate that the strait was formed mainly by an erosional event. Four seismic units are observed on seismic profiles. The lower two of these (units 4 and 3) constitute the basement of a regionally widespread erosional unconformity (ravinement), which developed during marine isotope stage 2 (MIS 2). The two upper units (units 2 and 1), which overlie the ravinement surface, form a higher-order sequence. Sequence stratigraphic analysis indicates that units 2 and 1 deposited as lowstand and highstand systems tracts respectively, since the end of MIS 2. The transgressive systems tract is represented by a major erosional event which occurred throughout the Çanakkale sill area when the Mediterranean-Marmara Sea connection and, hence, the Çanakkale Strait was formed. The existence of the erosive ?arköy Canyon along the shelf edge of the southern Marmara Sea demonstrates that the flow direction causing the erosion was from south to north, thus proving that it was produced by Mediterranean water flowing over the sill into the Marmara Sea basin. 相似文献
77.
Erkan Çelebi Muharrem Aktas Naci Çağlar Aşkın Özocak Mustafa Kutanis Necati Mert Zeki Özcan 《Natural Hazards》2013,65(3):2287-2310
On October 23, 2011, a magnitude of Mw 7.2 earthquake struck the Van province in eastern Turkey which caused approximately 600 life loss and 4,000 injured people. Although the recorded peak ground accelerations were relatively low (0.15–0.2 g) compared with that of other recent destructive Turkish earthquakes and the code-based design response spectrum, a large number of reinforced concrete buildings with 4–6 stories and non-engineered masonry buildings were either heavily damaged or collapsed in the region. Based on the post-earthquake technical inspections, the goal of this paper is to introduce major reasons for structural damages in the disaster area and to discuss these failures along with the approaches given in the design code which is renewed after August 17, 1999 Marmara Earthquake. Some remarkable lessons learned from earthquake-induced failures and damages specific to building construction techniques are presented in this paper. 相似文献
78.
The disaster experiences of the past resulted in the need for a new international policy. The paper examines the transfer of the international policy for disaster risk reduction (DRR) into a local context, Turkey and Turkish, where new and old perspectives meet. Analyzed is a corpus consisting of two texts, with the purpose of examining the concepts’ actual use and contexts shaped by different attitudes, based on the three-dimensional framework of critical discourse analysis, translation studies and conceptual history. The concept transfer from international to the local level inevitably involves translation. The texts included “new” DRR terms as a result of the concealed translation attempts to adjust the old and contemporary terminologies. Thus, non-functional terms with blurred meanings arose. The awareness that such processes of transfer are complex would help to overcome this kind of simplistic top-down approaches and to give priority to “communicative labor.” The framework is not presented due to space limitations. It was also observed that the Turkish terminology lacks clear definitions. To affirm this, an in-depth analysis is needed. Terms transferred across contexts may end lacking conceptualizations due to non-functional translation choices. When adopting new social policies, this can be overcome through making effort for communication. This research looks at conceptual struggles related to social issues from a different aspect. The vague terms and inefficiencies in social implementations can be avoided by authorities being aware that discourse, translation and their production are parts of social action. 相似文献
79.
GIS-based microzonation of the Niksar settlement area for the purpose of urban planning (Tokat, Turkey) 总被引：1，自引：1，他引：0
Niksar (Tokat) is an urban area located in a seismically active zone of Turkey. The aim of this study is to prepare a GIS-based microzonation map of the Niksar settlement area for the purpose of urban planning. Liquefaction, activity, slope, aspect, fault proximity, ground amplification, and lithology are considered during the overlay analysis, using a multicriteria decision-making analysis of the analytical hierarchy process (AHP) and simple additive weighing (SAW) methods. Based on the resulting evaluations, the study area is divided into four different zones, namely (1) areas suitable for settlement, (2) provisional settlement areas, (3) areas requiring detailed geotechnical investigation, and (4) unsuitable areas. Maps prepared by the SAW and AHP methods are found to be consistent with each other. However, the microzonation map prepared by the AHP method is recommended for the purpose of urban planning because it is able to check its own consistency. 相似文献
80.
We present the V light curves of δ Scuti type variable V350 Peg, obtained between August and October 2005 at the Ankara University Observatory (AUG) and the
TüBíTAK National Observatory (TUG). By application of multiple-frequency analyses using Period04 to 7878 photometric V measurements
(which are consist of our 747 V data and 7131 V data obtained at Monegrillo Observatory) of V350 Peg, a five-frequency solution
was found to be fitted well to the data. In accordance with the computed Q values for V350 Peg, it was found that this star
has probably radial mode with l=0 and g-mode oscillations. 相似文献