Nemrut (volcano) of the earliest trade routes. Two eruptions of Nemrut were probably witnessed by people of Urartu, an ancient state located in the eastern Turkey. These eruptions occurred c. 787 BC (period of King Menua) and c. 657 BC (period of King Rusa II), and the latter eruption might cause the sudden disappearance of the city Uaiais located 30 km east of Süphan. In the 1980s, Japanese volcanologists studied the evolution of gases inside the caldera of Nemrut. They found that the ratio of helium isotopes He/He is 1.06, which indicates volcanic activity (most of the measured helium evolved from the
Nemrut (volcano) northern edge of the caldera). The average height of the walls of the caldera, measuring from its bottom, is . The lowest point of the caldera coincides with the deepest point of Lake Nemrut ( above sea level). There are three lakes at the bottom of the caldera: the larger Lake Nemrut and two smaller ones, Ilı and the so-called "Seasonal Lake". Lake Nemrut () is located in the south-western part of the caldera and is now a freshwater lake. Similar to Lake Van, under the influence of volcanic processes it is gradually becoming a saline lake. The lake is