Figure 2. A: Bathymetry simplified from Aksu et al. (1999), depths of hypocenters of selected 1970–1998 earthquakes (Boaziçi University, Kandilli Geological Observatory; see koeri.boun.edu.tr), margins of principal deformation zone (PDZ, thick purple lines), and position of steeply dipping dextral master fault (thick pink lines) to west of Marmara Sea (= Saros-Ganos fault) and as dashed line where buried beneath elongate negative flower structure along axis of principal deformation zone. Of five principal basins, four straddle principal deformation zone and lie directly above buried North Anatolian transform fault. Soccer-ball–shaped symbols are lower-hemisphere projections of fault-plane solutions for selected large earthquakes (compiled by Kiratze and Papazachos, 1995; Wong et al., 1995; Yaltrak et al., 1998); quadrants with compressional first motion are black. B: Cross section along north-south line at ~27.6°E in A, showing distribution of earthquake hypocenters in band of latitudinal width 0.06', projected into cross section. Other cross sections are essentially identical and reveal location and dip of buried master fault (= North Anatolian transform fault) beneath principal deformation zone. Patterned region from 0 to 5 km depth is outline of principal deformation zone from seismic displays of Okay et al. (1999). Note lack of correlation between earthquake hypocenters and sidewall faults of principal deformation zone. C and D: Contradictory fault patterns proposed for Marmara Sea by various authors. E: Survey tracks of seismic grid used to construct Figure 1 and locations of seismic profiles of Figure 4.