NEOTECTONICS AND EARTHQUAKE POTENTIAL OF WESTERN ANATOLIA EXTENDED TERRAIN, TURKEY

Western Anatolia extended terrain is bounded by the Izmir-Ankara suture zone to the North to Northwest, the Lycian Nappes to the south, an easterly to northeasterly trending fault zone to the south and southeast which is named here as the West Anatolia Fault zone (WAFZ). It contains many large active normal faults including the fault zones that control the E-W trending Simav, Alasehir, Buyuk Menderes and Kucuk Menderes grabens. The WAFZ shows mostly normal movement in the vicinity of the Gulf of Gokova. However, its movement is mostly oblique slip from the vicinity of Tavas towards the lake of Acigol. The Neotectonics period in western Anatolia has followed the Alpine collision which produced the Izmir-Ankara suture zone. Available radiometric age determinations, including our limited number of monazite ages suggest that the north – northeast directed post-collisional extension was initiated in late Oligocene. The E-W trending major Graben systems formed in early Miocene when the detachment faults that form the northern margin of the Buyuk Menderes Graben and the southern margin of the Alasehir Graben were initiated. The westward movement of the Anatolian plate within the last 5 m.y. caused formation of the high angle faults that bounds the present flat topography of the Alasehir and Buyuk Menderes Grabens. Western Anatolia experienced many devastating earthquakes within the last 2000 years. Many of the ancient Greek/Roman city states, including Ephesus, Troy, and Hierapolis were destroyed by large historical earthquakes. During the second half of the 20th century, the region experienced two major large earthquake giving normal fault focal mechanism solutions. They are the 1969, M=6.9 Alasehir and the 1970, M=7.1 Gediz earthquakes. These earthquakes had caused substantial damage and loss of life in the region.