Hi All, last week I was at the combined spring meeting AGU-EGS etc in Nice France. I was there mainly to participate in sessions concerning the North Anatolian Fault in Marmara Sea, south of Istanbul, Turkey. Of interest-Rolando Armijo et al used multibeam (swath) bathymetry to locate fault scarps, used a robot to make very high resolution maps of scarps, and then took video along a submerged scarp. The big question is whether this scarp is from the M7 1/2 1912 earthquake, which also ruptures a long section onshore west of Marmara Sea (Ganos), or if it is older. Tom Rockwell et al presented some of his famous 3D trenches across the fault, and said that almost all of the motion is on this fault in the last hundreds or thousands of years-20 or 25 mm/yr that is shown by GPS (right-lateral, like San Andreas). Armijo's robot showed slickensides on the submerged fault surface-15 deg off of being pure horizontal. Cormier et al showed evidence that the 1999 Izmit surface/seafloor rupture did not reach as far west as Hersek peninsula in easternmost Marmara. The deeper rupture extended tens (?) of km farther west than the seafloor rupture-I think this happened also at Landers in 1992 (California). Several presented that there is a more-or-less continuous fault stretching the length of Marmara Sea-and that this is at the northern edge of Marmara Sea close to Istanbul. The section opposite Istanbul has not ruptured for a long time. It becomes important whether the scarp in western Marmara Sea, 50 km long, is from 1912 or is older. If older, the entire length of the sea would be a seismic gap. Construction is poor (esp on newer buildings (!) in Istanbul, and I think almost 2000 people were killed in Istanbul in the somewhat distant Izmit earthqake in 1999.I presented that some large features in SE Marmara Sea can be explained as contractional folds above blind thrust faults, rather than as extensional horsts and rollover anticlines, as many have interpreted. There is a releasing segment in that area on the main fault, where one would expect extension, but we suggest that some vertical axis clockwise rotation may allow N-S and NW_SE contraction at the same time as NE-SW extension.
Chris