Introduction

Although the active tectonics of both the western and eastern Mediterranean regions respond to a diffuse plate boundary between the Eurasia and Africa (Nubia) plates, including remnants of oceanic lithosphere being consumed by subduction, the geology is very different on either side of the Adriatic and Ionian seas between Italy and Greece. A major reason is the appearance of the rotating Anatolia Plate, driven westward and southwestward while the Arabia Plate forces its way northward into Eurasia. The North Anatolian and East Anatolian faults bounding the Anatolia Plate are strike-slip, as is the Dead Sea Transform fault between the Nubia and Arabia plates. Greece and most of western Turkey are on the overriding side of a north-dipping subduction zone extending in two loops (Hellenic Arc and Cyprian Arc) from the Ionian Sea east to the Levant coast of Syria and Turkey. The earthquake hazard consists of crustal earthquakes, particularly those related to strike-slip faulting and normal faulting, and an unknown hazard from earthquakes on or near subduction zones. Normal faulting related to Hellenic subduction takes place as far north as Bulgaria.

Even farther north, across the stable Moesian platform, the strongly arcuate Carpathian Mountains, related to subduction as a result of Nubia–Eurasia collision, frame the Pannonian Basin, a possible microplate. The southern end of the Eastern Carpathians, southeast of the Pannonian Basin, includes the Vrancea Zone, marked by deep earthquakes, possibly the last expression of a dying subduction zone. Aside from the deep earthquakes, the Carpathians are part of the Alpine system farther west, and, like the Alps, it is not always clear which structures are active and seismogenic and which are not. East of the Black Sea, the seismicity of the Caucasus Mountains continues across the central Caspian Sea into Turkmenistan, where the Kopeh Dagh Mountains are dominated by a fault of the same name.