Geology
The lake's outlet was blocked at some time during the Pleistocene, when lava flows from Nemrut volcano blocked westward outflow towards the Muş Plain. Now dormant, Nemrut Dağı is close to the western shore of the lake, and another dormant stratovolcano, Süphan Dağı dominates the northern side of the lake.
The water level of the lake has often altered dramatically: near Tatvan, Oswald (see Geology of Armenia, 1901) noted a raised beach high above the present level of the lake as well as recently drowned trees. Investigation by Degens and others in the early 1980s determined that the highest lake levels (72 metres (236 ft) above the current height) had been during the last ice age, about 18,000 years ago. About 9,500 years ago there was a dramatic drop to more than 300 metres (980 ft) below the present level. This was followed by an equally dramatic rise around 6,500 years ago.
Similar but smaller fluctuations have been seen recently. The level of the lake rose by at least three metres during the 1990s, drowning much agricultural land, and (after a brief period of stability and then retreat) seems to be rising again. The level rose about two meters in the ten years immediately prior to 2004.
As a deep lake with no outlet, Lake Van has accumulated great amounts of sediment washed in from surrounding plains and valleys, and occasionally deposited as ash from eruptions of nearby volcanoes. This layer of sediment is estimated to be up to 400 metres (1,300 ft) thick in places, and has attracted climatologists and vulcanologists interested in drilling cores to examine the layered sediments.
In 1989 and 1990, an international team of geologists led by Dr. Stephan Kempe from the University of Hamburg (now Professor at the Technische Universität Darmstadt) retrieved ten sediment cores from depths up to 446 m (1,463 ft). Although these cores only penetrated the first few meters of sediment, they provided sufficient varves to give proxy climate data for up to 14,570 years BP.
A team of scientists headed by palaeontologist Professor Thomas Litt at the University of Bonn has applied for funding from the International Continental Scientific Drilling Program (ICDP) for a new, deeper drilling project to examine the lake's sediments. Litt expects to find that "Lake Van stores the climate history of the last 800,000 years—an incomparable treasure house of data which we want to tap for at least the last 500,000 years." A test drilling in 2004 detected evidence of 15 volcanic eruptions in the past 20,000 years.
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