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

Abstract

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 Ç 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.

Distribution, morphology and triggers of submarine mass wasting in the Sea of Marmara

“…5) at 1100 m of water depth, implying that the slide affects the Palaeozoic basement of the Istanbul block and suggesting sliding surfaces may root in these black shales. The eastern part of the feature, separated by a NNE-SSW trending ridge, already described by Tur (2007), consists of a rough seafloor, with an average slope of 14°. It exhibits small normal faults and erosional gullies.…”

“…According to the convexity of the upper part of the landslide and to the hummocky topography of the landslide, Gökçeoğlu et al (2009) assumed that the Tuzla Complex is a deep-seated rotational landslide and proposed to relate it to the secondary NW-SE faults (Tur, 2007). One of the two cores recovered in this area by Özeren et al (2010) reached the top of the debris flow which is composed of angular mudstone clasts within a sandy mud matrix, 60 cm below the marine/lacustrine boundary.…”