Active faults in the Sea of Marmara, western Turkey, imaged by seismic reflection profiles

Abstract

Turkey is moving westward relative to Eurasia, thereby accommodating the collision between Arabia and Eurasia. This motion is mostly taken up by strike‐slip deformation along the North and East Anatolian Faults. The Sea of Marmara lies over the direct westward continuation of the North Anatolian Fault zone. Just east of the Sea of Marmara, the North Anatolian Fault splits into three strands, two of which continue into the sea. While the locations of the faults are well constrained on land, it has not yet been determined how the deformation is transferred across the Sea of Marmara, onto the faults on the west coast of Turkey. We present results from a seismic reflection survey undertaken to map the faults as they continue through the three deep Marmara Sea basins of Çlnarclk, Central Marmara and Tekirdag, in order to determine how the deformation is distributed across the Sea of Marmara, and how it is taken up on the western side of the sea. The data show active dipping faults with associated tilting of sedimentary layers, connecting the North Anatolian Fault to strike‐slip faults that cut the Biga and Gallipoli Peninsulas.

The active Main Marmara Fault

“…Its extreme youth (V2U10 5 a) stands in stark contrast to the much greater antiquity of the Marmara basins [13,42,44] and indicates that a signi¢cantly di¡er-ent mechanism must have formed the latter, before they were cut by the Main Marmara Fault about 2U10 5 a ago. There are also other active faults in the Sea of Marmara, mostly of normal type especially in the southern shelf area [45,46], whose relations to the Main Marmara Fault needs clari¢cation.…”

Seismic parameters re-determined from historical seismograms of 1935-Erdek–Marmara Island and 1963-Çınarcık Earthquakes

“…Also, the preferences for the solutions of the two possible planes (fault plane and auxiliary plane) were made by the tectonic properties and the knowledge of this region. Some studies show the existence of the normal faulting system in this area such as Parke et al (1999Parke et al ( , 2002 who mentions the basins that are half graben, formed on north dipping fault planes, in the southern Sea of Marmara by using regional grid of high-resolution seismic reflection profiles. They also reported that there is most likely a zone of deformation on the north of Marmara Island.…”

Crustal Strain in the Marmara Pull‐Apart Region Associated With the Propagation Process of the North Anatolian Fault

“…1b). Those sediments are cut by north and south dipping faults with significant normal component of slip, as observed in high-resolution bathymetric maps Armijo et al, 2002;, deep-penetration seismic reflection and refraction data [Wong et al, 1995;Parke et al 1999;Carton et al, 2007;Laigle et al, 2008;Bécel et al, 2009; and 2-D and 3-D high resolution multichannel seismic data [Grall et al, 2012;Kurt et al, 2013]. At odds with the evidence for structural complexity and fault segmentation which appear to be fundamental features of the pull-apart system, Imren et al [2001; [2003] and Şengör et al [2005], among others, have alternatively interpreted the Marmara pull-apart system as a trough resulting mainly from the Western Anatolia N-S extensional regime during the middle Miocene.…”