Because Gunay Cifci and the ship captain made a good team to acquire data across the shipping lanes, this lowered the stress level for "the Donna" and I. So, I spent some time in semi-deep thought (and talking to other scientists) to try and figure out how our new and 2008 data could tell something about the main active fault adjacent to Istanbul. One of the important questions that affects people is whether the fault will break in one M7 1/2 quake or in several smaller quakes, over time, in Marmara Sea. The same question is very important to Los Angeles and whether tall buildings will survive certain scenarios for earthquakes on the San Andreas and other faults.

Like southern California, the fault-fold array is complicated in this part of the North Anatolian system. There is a transverse ridge-anticline south of Istanbul. If it rotates clockwise, that will consume part of the right-lateral plate motion which will not be available for large earthquakes. According to Serdar Ozalabey when I talked to him in 2006, this ridge marks a gap in the small quakes, and to the west the base of seismicity is much deeper than to the east (I recall almost 10 km deeper). Our data will only image to about 2 km below sea floor, but combined with some reprocessing of deep crustal French seismic reflection data, maybe we will gain some insight.

One thing our imaging will tell, or already has, is the dip direction of the shallow NAF south of the vulnerable western Istanbul (airport area). If the shallow sediments are being squeezed, the fault likely dips north (because the relief is down-to-the-south). But, it is a bit difficult to distinguish folding related to downslope motion of the shallow rocks vs tectonic folding.
We think the fault dips north, and our data image that it likely does in the shallow part. This is bad for Istanbul there because an earthquake at, say, 15 km depth will be closer to beneath the coast than would be the case for a vertical or south-dipping fault.
Chris