An example of secondary fault activity along the North Anatolian Fault on the NE Marmara Sea Shelf, NW Turkey

Seismic data on the NE Marmara Sea Shelf indicate that a NNE-SSW-oriented buried basin and ridge system exist on the sub-marine extension of the Paleozoic Rocks delimited by the northern segment of the North Anatolian Fault (NS-NAF), while seismic and multi-beam bathymetric data imply that four NW-SE-oriented strike-slip faults also exist on the shelf area. Seismic data indicate that NW-SE-oriented strike-slip faults are the youngest structures that dissect the basin-ridge system. One of the NW-SE-oriented faults (F1) is aligned with a rupture of the North Anatolian Fault (NAF) cutting the northern slope of the Cinarcik Basin. This observation indicates that these faults have similar characteristics with the NS-NAF along the Marmara Sea. Therefore, they may have a secondary relation to the NAF since the principle deformation zone of the NAF follows the Marmara Trough in that region. The seismic energy recorded on these secondary faults is much less than that on the NAF in the Marmara Sea. These faults may, however, produce a large earthquake in the long term