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) fed by hot springs, which is why it is warmer at the bottom than at the surface and does not freeze in winter. The total area is 4.9×2.1 km, the average depth is 140 m, and the maximum depth is 176 m; the altitude of the lake is above the sea level. Lake Ilı (, "hot lake") was split from Lake Nemrut by an ancient lava flow. Ilı is located closer to the fault than Lake Nemrut; therefore it has a larger inflow of hot springs and a higher temperature. In the summer, it sometimes reaches 60 °C, and an