Characteristic features of the North Anatolian Fault in the eastern Marmara region and its tectonic evolution

Alpar, Bedri; Yaltırak, Cenk

doi:10.1016/s0025-3227(02)00353-5

Cited by 66 publications

(47 citation statements)

References 27 publications

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“…In addition to various knowledge about tectonics and geology of the Marmara Sea region, there are many researches on the shallow structure from seismic prospecting (Okay et al, 2000;Alpar and Yaltirak, 2002;Adatepe et al, 2002;Demirbag et al, 2003;Ateş et al, 2003;Özer et al, 2001) and some drilled wells for oil exploration. However, the deep structure in the Marmara Sea has not been well known.…”

Section: Discussionmentioning

confidence: 99%

Three-dimensional structure of Vp, Vs and Vp/Vs in the upper crust of the Marmara region, NW Turkey

et al. 2005

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We applied a 3-D seismic tomography inversion algorithm to arrival-time data obtained, during 18 years from 1985 to 2002, from local seismic networks and aftershock studies in the Marmara region, in order to better understand the upper crustal structure of the complex tectonic region. We integrated all the available data set into a common data set and relocated the events, using a 1-D velocity model. We then selected 3,949 earthquakes and obtained 92355 arrival times, in total, consisting of 59,313 P-wave and 33,042 S-wave arrival times. In this paper we present detailed crustal structures for V p, V s and V p/V s ratios from the surface down to 15 km depth with good resolution in terms of the hit count analysis of seismic rays, the checkerboard and restoring resolution tests for the studied region. The results obtained from the inversion suggest that the western part of the North Anatolian Fault Zone shows strong lateral heterogeneity. We concluded that no clear pattern exists between the distribution of microearthquakes and aftershocks and the velocity perturbations presented in this paper. This is probably due to complex tectonic and geological structures. Large coseismic slip associated with the two recent strong earthquakes was found to correspond to higher velocity anomalies, as was often found recently. On the other hand, low velocity values correspond to the sedimentary units or the alluvium regions, as supported by the low resistivity and gravity values. Thus the results presented in this paper are quite consistent with the other data such as gravity, resistivity and magnetic anomalies, indicating that our model is reliable and efficient and it should be useful for further interpretation of tectonic and geological problems in this region. It should be pointed out, however, that the results of S-wave perturbations and V p/V s ratio could not be discussed in detail because of insufficient quality of the S-wave data and the reliability of the results is not very high. Nonetheless, the fact that recent large Izmit earthquake and moderate aftershocks that occurred in or around the high velocity zones near the low velocity region suggests that high velocity regions found in the area close to Istanbul in the Marmara Sea and also at the Iznik-Mekece fault are potential sites for strain energy accumulation and release.

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Section: Discussionmentioning

confidence: 99%

Three-dimensional structure of Vp, Vs and Vp/Vs in the upper crust of the Marmara region, NW Turkey

et al. 2005

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“…Okay et al, 2000;Gö kaşan et al, 2001;Le Pichon et al, 2001, 2003Yaltırak, 2002;Alpar and Yaltırak, 2002;Elmas, 2003;Yigitbaş et al, 2004;Gü rer et al, 2003Gü rer et al, , 2006Dolu et al, 2007;Koral, 2007;Gü rbü z and Gü rer, 2008b;Schwab et al, 2009;Leroy et al, 2009). According to the latest detailed studies in the study area, the Izmit-Sapanca Corridor developed as an asymmetrical pullapart basin in the late Pliocene and Lake Sapanca originated as a different pull-apart basin in the Izmit-Sapanca asymmetric pull-apart basin by the cross-basin fault in the Middle Pleistocene (Gü rbü z and Gü rer, 2008bGü rer, , 2009.…”

Section: Geological Settingmentioning

confidence: 97%

“…The Samanlı Mountains to the south of the corridor rise very steeply to a maximum elevation of about 1600 m, and consist of Palaeozoic-Early Tertiary rocks. North of the corridor, the Kocaeli Peneplain has Ancient names of the regions, settlements and elements in northwestern Turkey and eastern Marmara region, and suggested routes for the Sakarya River-Lake Sapanca-Izmit Gulf connections in historical documents a 300 m average altitude, with maximum peaks reaching about 650 m. The Palaeozoic-Early Tertiary sedimentary rocks crop out as a northern uplifted basement adjacent to the basin-fill deposits of the corridor (Alpar and Yaltırak, 2002;Elmas, 2003;Yigitbaş et al, 2004;Gü rbü z and Gü rer, 2008a,b,c).…”

Section: Geological Settingmentioning

confidence: 99%

Science versus myth: was there a connection between the Marmara Sea and Lake Sapanca?

Gürbüz

Leroy

2010

J Quaternary Science

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The existence of an alternative strait between the Black and Marmara Seas, east of today's Istanbul Strait, on the route of Izmit Gulf-Lake Sapanca-Lower Sakarya Valley, was already claimed at the end of the 19th century and has also been considered in several recent studies. Firstly, in historical documents over the last 2500 years, some natural and artificial waterways between the Marmara Sea and Lake Sapanca have been reported. Secondly, according to the present geomorphological research between the Izmit Gulf and Lake Sapanca, the gutter-like morphology, which was formed by the tectonics of the North Anatolian Fault in the centre of the plain, is suggested as a suitable geomorphic feature for a possible waterway between the gulf and the lake. Thirdly, the Izmit Plain that lies between the Izmit Gulf and Lake Sapanca is studied in this paper through its sedimentology. The facies associations of the basin-fill deposits are examined here through the lithological descriptions and fossil assemblages in nine cores drilled in the plain. All these data suggest that the shoreline in the Quaternary did not lie much further landward from its current position, that the inner part of the plain was covered by a lagoon/coastal-swamp environment and that a connection may have existed at an unknown time (perhaps for the last time during the Middle/Late Pleistocene) with perhaps only partial reuse during the last millennia in the course of catastrophic seismic movements and consecutive floods.

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“…It extends from the east of Iznik Lake to the northern slopes of the UM along the Yenisehir plain (OZTURK et al, 2009). The BF extends in an E-W direction for a distance of 45 km between the UF and the city of Bursa, showing a right-lateral strike-slip character with a normal component (ADATEPE et al, 2002;ALPAR and YALTIRAK, 2002;KUSCU et al, 2009;YALTIRAK and ALPAR, 2002). The IEFZ follows a NW-SE direction for a distance of 380 km up to the city of Bursa.…”

Section: Geology and Tectonic Settingmentioning

confidence: 96%

An Assessment of the Seismicity of the Bursa Region from a Temporary Seismic Network

Gök

Polat

2011

Pure Appl. Geophys.

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A temporary earthquake station network of 11 seismological recorders was operated in the Bursa region, south of the Marmara Sea in the northwest of Turkey, which is located at the southern strand of the North Anatolian Fault Zone (NAFZ). We located 384 earthquakes out of a total of 582 recorded events that span the study area between 28.50-30.00°E longitudes and 39.75-40.75°N latitudes. The depth of most events was found to be less than 29 km, and the magnitude interval ranges were between 0.3 B M L B 5.4, with RMS less than or equal to 0.2. Seismic activities were concentrated southeast of Uludag Mountain (UM), in the Kestel-Igdir area and along the Gemlik Fault (GF). In the study, we computed 10 focal mechanisms from temporary and permanents networks. The predominant feature of the computed focal mechanisms is the relatively widespread near horizontal northwest-southeast (NW-SE) T-axis orientation. These fault planes have been used to obtain the orientation and shape factor (R, magnitude stress ratio) of the principal stress tensors (r 1 , r 2 , r 3 ). The resulting stress tensors reveal r 1 closer to the vertical (oriented NE-SW) and r 2 , r 3 horizontal with R = 0.5. These results confirm that Bursa and its vicinity could be defined by an extensional regime showing a primarily normal to oblique-slip motion character. It differs from what might be expected from the stress tensor inversion for the NAFZ. Different fault patterns related to structural heterogeneity from the north to the south in the study area caused a change in the stress regime from strike-slip to normal faulting.

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Characteristic features of the North Anatolian Fault in the eastern Marmara region and its tectonic evolution

Cited by 66 publications

References 27 publications

Three-dimensional structure of Vp, Vs and Vp/Vs in the upper crust of the Marmara region, NW Turkey

Three-dimensional structure of Vp, Vs and Vp/Vs in the upper crust of the Marmara region, NW Turkey

Science versus myth: was there a connection between the Marmara Sea and Lake Sapanca?

An Assessment of the Seismicity of the Bursa Region from a Temporary Seismic Network

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