There was a M4.9 or 5 quake just north of the sea floor trace of the main active strands of the North Anatolian fault (link). This is in Marmara Sea where our group has been working since 2008 (and some of us since the 1999 quakes, but not me). The focal mechanism (other site: http://www.emsc-csem.org/Earthquake/earthquake.php?id=272262#map)
shows 4 versions: one is the expected pure right-lateral. But, this is the location of the edge of a NE-SW ridge full of blind (oblique) thrust faults and constractional folding. Another map shows an alignment of ENE-WSW quakes so need not be on the main E-W fault.

Everytime there is a quake near the main faults, people in Istanbul get nervous.

Chris

• Marmara M4.9