Nemrut Dağı Location: 38.65° N, 42.23° E Elevation: 2.948 m Nemrut Dağı is a polygenic stratovolcano  located in the collision zone of the Arabian and  Eurasian tectonic plates, which determines the  seismic and volcanic activity in the region. The  collision of these plates began in the Middle  Eocene and closed the stretch of water, which  in the Mesozoic formed the Tethys Ocean.  Nemrut, along with three other extinct  volcanoes of eastern Turkey: Ararat, Tendürek  and Süphan, is located in the area of a complex  fault, which runs along the boundary of the  Arabian and Eurasian plates in the territory of  the Armenian Highland. It is the westernmost of  these volcanoes, the only one that remains  active, and generally the only volcano in  Anatolia, which erupted in the historical period. Nemrut is located 10 km north of the city Tatvan, in  the north-western shore of Lake Van. Nemrut was probably formed in the early Quaternary Period,  about 1 million years ago. It showed the greatest activity in the Pleistocene, with regular eruptions  occurring in the Holocene. In the middle Pleistocene, about 250,000 years ago, a major eruption  formed a lava flow over 60 km long, which blocked the water discharge from the Van basin and  formed Lake Van, the world's largest alkali endorheic lake. In the same period, the conical top of  the volcano collapsed inward, forming a 8.3×7 km caldera. Later, the freshwater Lake Nemrut  formed inside the caldera, becoming the world's second largest caldera lake. Nemrut volcano has  an elliptical shape, its size at the base is 27×18 km, and its center contains 377.5 km3 of volcanic  materials. The caldera of Nemrut is the largest in Turkey, the fourth largest in Europe and sixteenth  largest in the world. Post-caldera volcanism, of basaltic to rhyolitic composition, initially occurred  along the caldera rim and floor. Pyroclastic flows and the emission of glassy obsidian lava flows  accompanied construction of lava domes within the caldera; later activity formed a series of cinder  cones and lava domes erupted along N-S-trending fissures on the northern flank. The most recent  activity has been concentrated along a NNW-trending fissure cutting the eastern caldera floor and  extending beyond the north caldera rim; nearly two dozen cinder cones and lava domes were  constructed on the caldera floor. Ash layers in Lake Van document numerous Holocene eruptions,  and an historical eruption in 1441 AD from a north-flank fissure involved compositionally bimodal  lava flows. Photo: NASA Photo: Rolf Cosar Photo: Rolf Cosar GoogleEarth Photo: Rolf Cosar Photo: Rolf Cosar Photo: Rolf Cosar Photo: Rolf Cosar Photo: Rolf Cosar 22. May 2010 HOME Photo: Rolf Cosar Photo: Rolf Cosar