CONCLUSIONS

Analysis of the data collected during the MARM05 expedition is under process, and will continue during the forthcoming several months. However, because of the potential impact of our findings in term of earthquake risk assessment, and requests from IBB and other Turkish institutions, a preliminary data analysis was carried out on board of Urania during the cruise, for two areas: (a) the northern Marmara shelf in the Princes Island area, and (b) the Gulf of Gemlik, in the southern shelf.

During a 22 days (of total 27 including transits) cruise in the Marmara and NE Aegean Sea we obtained:

• high resolution bathymetric images and DTMs of the investigated areas (aproximately 1300 km$^2$).
• a detailed grid of high resolution CHIRP-SBP (ping rate 0.25,1,2s) profiles to examine fault traces and sedimentary processes (4900 km)
• high resolution MCS lines (274 km)
• bottom samples (28 cores, 7 grabs)
• water column CTD profiling

Multibeam swath bathymetry and chirp-sonar subbottom profiles have been processed and preliminarly interpreted to address the following tasks:

• identification of morphotectonic features related to the NAF;
• identify active faults;
• define a seismostratigraphic framework;
• look for "piercing points" for slip-rate estimates along the main fault strand.

Preliminary morpho-structural maps compiled on the basis of these data show the presence of several active faults, outcropping at the seafloor (Fig.24). Strike-slip and dip-slip extensional segments oriented E-W and NW-SE, respectively, were observed.

Although a further processing and interpretation of the data is required to define strain pattern and deformation rates, we could observe that:

• the seafloor of the Princes Island shelf and of the Gulf of Gemlik is affected by diffuse faulting and fracturing, mainly due to transtensional deformation patterns possibly related to a left-stepping offset along the NAF;
• most of the faults observed appear to be active, as they displace the uppermost sedimentary sequence and, from place to place, the seafloor;
• some sedimentary features formed during the Last Glacial Maximum observed in the area appear also displaced along major fault strands; this occurrence will be analyzed for long-term strain rate estimates.

The data is under detailed processing and analysis, and we expect to have new insights into the geology of the investigated areas.

No problems were encountered regarding neither the people nor environment during the cruise.