The Sea of Marmara is dissected by Two major fault systems. The first consists of two east-west-striking, transtensional boundary faults and a number of secondary faults subparallel to them. The second is made up of NE-SW-trending, subvertical strike-slips and their conjugates oriented NW-SE that offset the first system. These fault systems segment the deep Marmara Sea into 5 blocks that are either rhomboidal, lazy-Z or wedge-shaped. Three of these blocks may be interpreted as pull-apart basins characterized by transtension, while the other two (sill areas) which separate the basins are transpressional push-up structures. The blocks are subjected to rapid, episodic subsidence, but they also undergo pervasive vertical motions and possible rotations relative to one another.