Todd, yes, they have a long historic record, and it is probably pretty good. However, I have not looked into this...although others have. Ambraseys (sp?) has published on ancient middle east quakes...including Turkey, checked with HW. HW says last major quake affecting Istabul was 1766. They are concerned about Istanbul because almost all of the North Anatolia fault in Turkey broke during the 20th century, the last 2 being 1999, but the one section opposite Istanbul did not.
Chris