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 C¸ ınarcık 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.
Key words: Marmara Sea Shelf, North Anatolian Fault (NAF), secondary fault activity.