Tuz Golu Fault Zone Research Articles

Tuz Gölü Fay Zonu (TGFZ) Güney Kesimine ait Tektonik Hareketlerin GNSS Gözlemleri ile İzlenmesi

Günümüzde aktif fayların yakın alanlarına kurulan deformasyon ağlarının GNSS tekniği ile izlenmesi sonucunda depreme ait zamanı belirlemek mümkün olmasa da faylar üzerinde biriken gerilmeler yardımıyla muhtemel deprem konumları tahmin edilebilmektedir. Orta Anadolu Neotektonik Bölgesini, Konya-Eskişehir ve Kayseri-Sivas Neotektonik Bölgeleri olmak üzere iki alt neotektonik bölgeye ayıran bir geçiş zonu olan yaklaşık 220 km uzunluğundaki Tuz Gölü Fay Zonu (TGFZ)’nun kırılması durumunda büyüklüğü (M) yaklaşık 6-7 olan bir depreme sebep olabileceği bilinmektedir. Fay zonunun bu potansiyeli dikkate alınarak, bulunduğu alanda meydana gelen deformasyonların hesaplanması amacıyla Tuz Gölü Fay Zonu’nun Güney Kesiminde doğu-batı yönlü profil şeklinde 24 adet nirengi tesisi kurulmuştur. Oluşturulan ağda 2018-2019 yıllarında 3 periyot GNSS ölçüsü yapılmış ve elde edilen sonuçlar GAMIT/GLOBK yazılım takımı ile değerlendirilerek bölgenin güncel hız haritası elde edilmiştir. Yapılan çalışmada, Tuz Gölü Fay Zonu Güney kesiminde Avrasya referans sistemi sabit olmak üzere yıllık 10 ile 35 mm arasında batı ve kuzey batı yönünde bir hareket belirlenmiştir. Noktalara ait standart sapma değerleri 2-6 mm arasında değişmektedir. İlerleyen yıllarda yapılan yeni kampanya ölçüleri ile birlikte standart sapma değerlerinin azalacağı düşünülmektedir.

Geomorphology and tephrochronology review of the Hasandağ volcano (southern Cappadocia, Turkey)

This research proposes a suite of volcanic events that took part in the edification of the double-peaked Hasandag stratovolcano in southern Cappadocia. Inter-correlations of sections dispatched along geographic transects across the volcano evidence continuities/discontinuities and stratigraphic relationships using key layers identified through this process which is, later, framed by a radiometric dating control of some of these formations. The main goal is to provide some chronological markers of the geomorphological evolution of the volcano. The stratigraphy, lithology and facies, the landform definitions and new dates provide information about eruption types and their role in shaping the morphologies of the volcano through time. Recent ages from literature and seven new K/Ar dates contribute in enriching the story of the volcanic activity that built the Hasandag stratovolcano landforms. The part of the story exposed in this article starts mainly c. 700/650 ka ago with the construction of a Mid-Pleistocene volcano. Later, between 220 and 120 ka ago, main events occurred in the NE part of the volcano. After an initial Plinian eruption, a caldera collapse is recorded by pumice flows. Close to the emission point, a small collapse structure is today filled with a much younger dacite flow. After the Plinian eruption, the partial destruction of a volcano caused one or two avalanches containing several meters-thick distinct blocks that flew north c. 16–18 km over the roof of the Cappadocian Miocene ignimbrites. Remains of the destructed volcano flanks are not visible. Either they are buried below younger lava flows forming the Kucuk Hasandag cone, or a seism in the Tuz Golu Fault Zone during the avalanche may have resulted in an explosion. This event was followed by extrusion of rhyolitic domes positioned on the caldera rim, emitting pumice falls now filling-in the Guvercin valley stream down to Ihlara village. During Late Pleistocene emission of andesite and dacite flows and domes, accompanied by several pyroclastic flows formed today’s terminal cones of the stratovolcano.

Determination of Structural Characteristics of Tuzgölü Fault Zone Using Gravity and Magnetic Methods, Central Anatolia

The anomaly maps and amplitude and wavelength changes of the anomalies obtained from gravity and magnetic methods can provide to identify fault traces in the underground. The Tuzgolu Fault Zone (TFZ), the NW-SE striking active fault zone in central Anatolia, includes fault strands that cut the basement and basin deposits. Our magnetic and gravity analysis suggests that Tuzgolu Basin and its surroundings are characterized by distinct depression and ridge areas. Gravity anomaly data show the presence of faults at depths of sea level (0 m), -1000 m, -2000 m, -3000 m, and -4000 m. These faults are mostly normal and reverse faults, as well as the lesser amount of vertical faults (high-angle normal/reverse faults) with NW-SE, N-S, and NE-SW-striking. The normal faults are of the structural development and the deposition of the Tuzgolu Basin units, which occurred late Cretaceous-Middle Eocene and Early Miocene-Quaternary Periods. The reverse faults originated from the result of the regional-scale compressional regime during Middle Eocene-Late Oligocene/ Early Miocene based on the fault dating data from the literature. The active TFZ, including several fault strands, are relatively younger faults in the region that have initiated to develop during faulting events from after Middle Miocene or Early Pliocene.

Geomorphological evolutionary history of the Melendiz River Valley, Cappadocia, Turkey

The Melendiz River is located at the east of Tuz Golu Fault Zone in western Cappadocia. In the central part of Melendiz River Valley, Ihlara Canyon attracts many tourists due to its landscape, cultural and archaeological values. The Melendiz Valley also encompasses geological and geomorphological features that exemplify the evolutionary history of western Cappadocia. In this study, the late Miocene–Quaternary geomorphological evolution of the Melendiz River Valley was investigated. The results indicate that a fluvial sedimentary sequence with ignimbrite intercalation was deposited during the late Miocene and early Pliocene. This was unconformably overlain by lacustrine limestone (Kisladag Formation) of Pliocene age. The Pliocene lake regressed westward because of the changes in the tectonic regime and geomorphological processes during the late Pliocene (~ 3 Ma ago) and the initial Melendiz River developed on the lake bottom. During the Quaternary the Melendiz River developed under the control of both the neotectonic regime and the climate. This development provoked a 160-m-deep incision into the Pliocene sediments and the early Pliocene–Miocene ignimbrites below, giving birth to the Ihlara Canyon. In the proper valley of the Melendiz River, six strath terraces and Holocene flood plain record the incision process.

U/Th Dating of the Akhüyük Fissure Ridge Travertines in Ereğli, Konya (Central Anatolia, Turkey): Their Relationship to Active Tectonics

Fissure ridge travertines that form the Akhuyuk travertine mass are located in Central Anatolia and are exposed in an area of 1.5 km $$^{2}$$ with N30 $$^{\circ }$$ W direction. These fissure ridge travertines have ages determined between 3345 ± 105 yr and 47850 ± 980 yr by U-series dating methods. Development of the travertines can be correlated with faults that have been active since the late Pleistocene. The dilation rate in the Eregli (Konya) basin was determined using age data and the widths of the banded travertines at the opening center of the fissure ridge travertines. The dilation rate for the formation of Akhuyuk travertines yields 0.025–0.05 mm yr $$^{-1}$$ on average. When considering positions and extension directions of fissure ridge travertines, they are consistent with the Tuz Golu Fault Zone which is one of the most important structures in the region. The maximum earthquake intensity potential in this region is estimated to be $$M_\mathrm{s}$$ 6.3, when the dilation rate of the fissure ridge travertines is taken to be 0.05 mm yr $$^{-1}$$ and with a 10,000-year earthquake recurrence interval.

The 2005 - 2007 Bala (Ankara, central Turkey) earthquakes: a case study for strike-slip fault termi

An intense seismic activity has been observed after the Bala (Ankara, NW central Turkey) earthquakes (30 July 2005: Mw=5.3, 20 December 2007: Mw=5.4, and 26 December 2007: Mw=5.3), continuing up to the present. The epicenters and the focal mechanism solutions of the earthquakes indicate that the right lateral strike-slip Afsar fault, trending N55-60°W, is responsible for the main shocks. The Afsar fault is thought to be the NW continuation of the Tuzgolu fault zone, which is one of the main neotectonic elements in central Anatolia. On the other hand, the aftershock distributions of the 2005 event have a NNE trend, and those of the 2007 event show a NW trending. Some focal mechanism solutions of the 2005 Bala earthquake aftershocks indicate normal and oblique normal faulting that corresponds to the NNE-trending Karakecili fault. It seems that seismic activation of the NNE-trending Karakecili fault was triggered by the 2005 main shock (Mw=5.3) that occurred on the NW trending right lateral strike-slip Afsar fault. The overall neotectonic framework is that the northwestern edge of the Tuzgolu fault zone, represented by the Afsar fault in Bala, terminates in an extensional system represented by the oblique-slip Karakecili fault.

Liquefaction severity map for Aksaray city center (Central Anatolia, Turkey)

Abstract. Turkey having a long history of large earthquakes have been subjected to progressive adjacent earthquakes. Starting in 1939, the North Anatolian Fault Zone (NAFZ) produced a sequence of major earthquakes, of which the Mw 7.4 earthquake that struck western Turkey on 17 August 1999. Following the Erzincan earthquake in 1992, the soil liquefaction has been crucial important in the agenda of Turkey. Soil liquefaction was also observed widely during the Marmara and the Düzce Earthquake in 1999 (Sönmez, 2003). Aksaray city center locates in the central part of Turkey and the Tuzgolu Fault Zone passes through near the city center. The fault zone has been generated to moderate magnitude earthquakes. The geology of the Aksaray province basin contains Quaternary alluvial deposits formed by gravel, sand, silt, and clay layers in different thickness. The Tuzgolu Fault Zone (TFZ) came into being after the sedimetation of alluvial deposits. Thus, the fault is younger from lithological units and it is active. In addition, the ground water level is very shallow, within approximately 3 m from the surface. In this study, the liquefaction potential of the Aksaray province is investigated by recent procedure suggested by Sonmez and Gokceoglu (2005). For this purpose, the liquefaction susceptibility map of the Aksaray city center for liquefaction is presented. In the analysis, the input parameters such as the depth of the upper and lower boundaries of soil layer, SPT-N values, fine content, clay content and the liquid limit were used for all layers within 20 m from the surface. As a result, the category of very high susceptibility liquefaction class was not observed for the earthquake scenario of Ms=5.2, 4.9% of the study area has high liquefaction susceptibility. The percentage of the moderately, low, and very low liquefied areas are 28.2%, 30.2%, and 36.3%, respectively. The rank of non-liquefied susceptibility area is less than 1%.

Neotectonic Characteristics of Central Anatolia

The Central Anatolian Crystalline Complex and its Tertiary cover have been highly dissected by neotectonic structures. The period of neotectonic activity is dominated by three main fault systems in Central Anatolia—the Tuzgolu fault zone, the Ecemis fault zone, and the Yozgat-Akdagmadeni-Bogazliyan fault system. The Tuzgolu fault zone, trending in a NW-SE direction, is located WSW of the Central Anatolian Crystalline Complex (CACC). This fault zone consists of parallel to subparallel, normal, and oblique right-lateral strike-slip faults displaying a step-like half-graben and horst-graben pattern. It controls the eastern margin of Tuzgolu, fault-parallel depressions, and the western margin of the Central Anatolian volcanic province. The Ecemis fault zone is located east of the CACC and is characterized by NE-SW-trending, left-lateral strike-slip faults controlling the eastern margin of the Central Anatolian volcanic province. The Yozgat-Akdagmadeni-Bogazliyan region is dominated by NW-SE- and NE-SW-trendin...