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

Bedri Alpar*, Cenk Yaltirak

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

66 Citations (Scopus)


Shallow seismic profiles are used to image the tectonic and stratigraphic setting in Izmit Bay, eastern Marmara Sea. Four seismic units were detected in the sediments of Izmit Bay, which carry the effects of the tectonic uplift and global sea-level variations. The area appears to be a negative flower structure controlled by the northern branch of the North Anatolian Fault. In the late Pliocene the North Anatolian Fault reached Marmara Sea as a master fault. Small-scale faults were evolved around the master fault under a regime of dextral shear. The northward bending of the master fault gave rise to en-echelon faults, opening the sub-basins in Izmit Bay as releasing bends. The secondary faults which developed as low-angle oblique to the master fault are also the products of dextral shear. To the south, short dextral ENE-WSW trending faults are interpreted as 'P'-shears, while to the north, dextral WNW-ESE trending faults represents 'R'-shears. These faults absorbed the deformation at the western end of the ruptured zone during the Izmit Earthquake (August 17, 1999), causing the migration of failure stress westward.

Original languageEnglish
Pages (from-to)329-350
Number of pages22
JournalMarine Geology
Issue number1-2
Publication statusPublished - 15 Oct 2002


We thank Dr. Ertuǧrul Doǧan, head of the Institute of Marine Sciences and Management, and Dr. Kemal Alemdaroǧlu, the Rector of the Istanbul University for their support of this study. We thank the Captain, scientists and crew of the RV Arar for their attention and effort during the cruise. We thank M.C.J. Zschau and other anonymous reviewers for their contribution. Part of this study was supported by Istanbul University, Research Fund (Project B-403/13042000).

FundersFunder number
Istanbul ÜniversitesiB-403/13042000


    • Active faults
    • Izmit Bay
    • Marmara Sea region
    • North Anatolian Fault
    • Reflection
    • Seismic profiles


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