Nemrut (volcano)
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Nemrut ( tr, Nemrut Dağı, hy, Սարակն ''Sarakn'', "Mountain spring", , ku, Çiyayê Nemrudê) is a dormant
volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...
in Eastern
Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
, close to
Lake Van Lake Van ( tr, Van Gölü; hy, Վանա լիճ, translit=Vana lič̣; ku, Gola Wanê) is the largest lake in Turkey. It lies in the far east of Turkey, in the provinces of Van and Bitlis in the Armenian highlands. It is a saline soda lake ...
. The volcano is named after King Nimrod who is said to have ruled this area in about 2100 BC. The most powerful eruptions of Nemrut occurred in the
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
. Many small eruptions occurred during the
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
, the last in 1650. The top of the volcano is a large
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
hosting three
crater lake Crater Lake (Klamath language, Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The ...
s.


Overview

Nemrut is a
polygenic A polygene is a member of a group of non-epistatic genes that interact additively to influence a phenotypic trait, thus contributing to multiple-gene inheritance (polygenic inheritance, multigenic inheritance, quantitative inheritance), a type of ...
stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
located in the collision zone of the
Arabian The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate. ...
and
Eurasian Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...
tectonic plate Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
s, which determines the seismic and volcanic activity in the region. The collision of these plates began in the Middle
Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
and closed the stretch of water, which in the
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
formed the
Tethys Ocean The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...
. 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 Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...
, which erupted in the historical period. Nemrut is located 10 km north of the city
Tatvan Tatvan ( ) is a city on the western shore of Lake Van. It is the chief city of Tatvan District within Bitlis Province in eastern Turkey, and has about 96,000 inhabitants. The current Mayor is Mehmet Emin Geylani ( AKP). The district is fully Kurdi ...
, in the north-western shore of
Lake Van Lake Van ( tr, Van Gölü; hy, Վանա լիճ, translit=Vana lič̣; ku, Gola Wanê) is the largest lake in Turkey. It lies in the far east of Turkey, in the provinces of Van and Bitlis in the Armenian highlands. It is a saline soda lake ...
. Nemrut was probably formed in the early
Quaternary Period The Quaternary ( ) is the current and most recent of the three period (geology), periods of the Cenozoic era (geology), Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spa ...
, 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 an 8.3×7 km caldera. Later, the freshwater Lake Nemrut formed inside the caldera. Subsequent eruptions separated a small lake Ilı from Lake Nemrut. 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.


History of study


Etymology

Locals link the name of the volcano with the legendary ruler
Nimrod Nimrod (; ; arc, ܢܡܪܘܕ; ar, نُمْرُود, Numrūd) is a biblical figure mentioned in the Book of Genesis and Books of Chronicles. The son of Cush and therefore a great-grandson of Noah, Nimrod was described as a king in the land of ...
, who is credited with the construction of the
Tower of Babel The Tower of Babel ( he, , ''Mīgdal Bāḇel'') narrative in Genesis 11:1–9 is an origin myth meant to explain why the world's peoples speak different languages. According to the story, a united human race speaking a single language and mi ...
. Turkish chronicles of the 16th century reproduce a local legend as follows:


Medieval chronicles

Eruptions of Nemrut are mentioned in Armenian sources of the 15th century and Kurdish sources of the 16th century. These records allowed to confirm the activity of the volcano during the Holocene and to establish the dates of some eruptions. A more recent eruption is mentioned in Turkish records: The Armenian name of the volcano ( hy, Սարակն: angry) might also reflect the regular activity of the volcano in the historical period.


Studies in the 19th century

The first systematic studies of the volcano began in the mid-19th century, when, taking advantage of the British influence in the region, it was visited by several European explorers. They described and mapped the area, and some, including the British archaeologist
Austen Henry Layard Sir Austen Henry Layard (; 5 March 18175 July 1894) was an English Assyriologist, traveller, cuneiformist, art historian, draughtsman, collector, politician and diplomat. He was born to a mostly English family in Paris and largely raised in It ...
, explored the remains of
Urartu Urartu (; Assyrian: ',Eberhard Schrader, ''The Cuneiform inscriptions and the Old Testament'' (1885), p. 65. Babylonian: ''Urashtu'', he, אֲרָרָט ''Ararat'') is a geographical region and Iron Age kingdom also known as the Kingdom of Va ...
fortresses around Lake Van. In this period it was suggested that the unusual structure of the watersheds in the region, and the very formation of Lake Van, is related to a large volcanic eruption and the blocking of the water discharge to Murat River by the lava flow. The most detailed work on the subject was the doctoral thesis of the English scientist Felix Oswald, "A Treatise on the Geology of Armenia", which devotes a large part to Nemrut. Oswald made and documented many measurements and observations. He also suggested possible ways of the evolution of Nemrut, most of which were confirmed later.


Modern research

In the 20th century, the scientific study of the volcano was interrupted by the political instability in the region. In the first half of the 20th century Nemrut was wrongly classified as an extinct volcano. Only in the 1980s, with the resumption of the studies, its status was changed to dormant. Currently Nemrut is mainly studied by Turkish
volcanologist A volcanologist, or volcano scientist, is a geologist who focuses on understanding the formation and eruptive activity of volcanoes. Volcanologists frequently visit volcanoes, sometimes active ones, to observe and monitor volcanic eruptions, col ...
s. The volcano is still poorly understood, and there is no consensus on the interpretation of
stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostrati ...
data. Analysis of the sediments of Lake Van, which is near the volcano, allowed clarification of the chronology and activity of recent eruptions. The potential activity of Nemrut and the close proximity of several Turkish cities inspired recent in-depth studies. In October 2003, the first in Turkey real-time seismic network of sensors has been installed around the volcano. During the first three years of operation the network has registered 133 seismic events with a magnitude of 1.3–4.0.


Volcanic activity

Eruptions of Nemrut were mainly of Plinian type. Their products are mainly alkaline and include a wide range of lavas: from
basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
to
rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...
and
phonolite Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous ...
, as well as
pyroclastic Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...
emissions and
slag Slag is a by-product of smelting (pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or non-ferrous/base metals (by-prod ...
. Eruption of different periods were either effused or explosive. Nemrut is located on a fault that crosses the volcano from the north to the south and contains the main crater and a number of small craters,
maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...
s, hot springs and
fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...
s. The volcanic activity of Nemrut occurred in three stages: the formation of a cone (pre-caldera stage), the post-caldera stage, and the late stage. Further, divisions are debatable and are based on different interpretations of the stratigraphic data.


Formation of volcanic cone

The formation of Nemrut and the first stage of eruptions began about 1 million years ago with fissure eruptions that later localized in separate vents separated by 5–10 km. These eruptions resulted in a strong (thicker than 50 m) layer of successive pyroclastic deposits consisting mainly of
trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and al ...
. Their products covered an area of 500 km2, forming a plateau that hid the continental deposits of the Miocene period. The cone of Nemrut was further formed by mobile dark trachytic lavas, which gradually filled Bitlis gorge to a distance of 80 km from the volcanic center. Lava flows reached a width of 200 m and had a thickness of 5–30 meters. Consequent deposits from basalt and trachytic lavas finalized a pronounced cone with a height of about 4400-4500 m. The next major eruption (volume 62.6 km3) created large voids inside the volcano, which led to the collapse of the apex and the formation of the caldera. Initially it was assumed that the caldera formed right after this eruption, about 310 thousand years ago; however, more recent studies suggest that the collapse happened with the next eruption, about 270 thousand years ago. The products of this eruption mostly consisted of
ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...
s (c. 58.2 km3). Thus the collapse of the cone occurred gradually, probably in three stages.


Post-caldera stage

After the formation of the caldera, eruptions were localized to its edge and formed more than ten of small craters, mostly on the northern edge. The products were dominated by viscous trachyte and rhyolite lavas. Pyroclastic flow deposits were accumulating on the bottom of the caldera, forming ignimbrites and
obsidian Obsidian () is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Obsidian is produced from felsic lava, rich in the lighter elements s ...
, and sometimes slag
pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular vol ...
. A cone-shaped crater Göltepe (height 2,485 m above sea level) formed at the bottom of the caldera, on the fault line.


Late stage

At this stage, about 20 small craters and maars formed at the cracks located on the caldera floor, mostly along the central fault. A number of craters with a diameter of 10–100 m formed outside of the main cone, mainly in its northern part. They include Girigantepe (2433 m), Arizintepe (2445 m), Kayalitepe (2311 m), Mezarliktepe (2409 m), Atlitepe (2281 m), Amis (2166 m), Kevriağa (2087 m), Avuştepe and Sivritepe, which is the highest point of Nemrut. Basaltic lava of these craters are the youngest volcanic rocks within Nemrut. The last eruption took place on 13 April 1692. Since then only bursts of steam were observed at the bottom of the caldera, indicating
fumarolic A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...
activity.


Summary of eruptions


Historical role

Besides the legendary relationship of the volcano with King Nimrod, in 1990s scientists discovered that Nemrut played an important role in the life of the first civilizations. Despite the abundance of obsidian sources in Anatolia and Iran, Nemrut was the main source of obsidian – the most important material of the
Stone Age The Stone Age was a broad prehistoric period during which stone was widely used to make tools with an edge, a point, or a percussion surface. The period lasted for roughly 3.4 million years, and ended between 4,000 BC and 2,000 BC, with t ...
– for all settlements in Mesopotamia and the settlements of the Mesolithic era around the Dead Sea. The analysis of obsidian products revealed that the population of those areas used obsidian from only two sources: Nemrut and the nearby dormant volcano
Bingöl Bingöl ( diq, Çolig; ku, Çewlik; hy, Ճապաղջուր, translit=Chapaghjur) is a city in Eastern Turkey and the capital of Bingöl Province. Etymology One of the historical names for the city, ''Bingöl'' literally means ''thousand lak ...
. An ancient center of obsidian processing and trade was found at Lake Van, which was part of one of the earliest trade routes. Two eruptions of Nemrut were probably witnessed by people of
Urartu Urartu (; Assyrian: ',Eberhard Schrader, ''The Cuneiform inscriptions and the Old Testament'' (1885), p. 65. Babylonian: ''Urashtu'', he, אֲרָרָט ''Ararat'') is a geographical region and Iron Age kingdom also known as the Kingdom of Va ...
, 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.


Present state


Volcanic activity

In the 1980s, Japanese volcanologists studied the evolution of gases inside the caldera of Nemrut. They found that the ratio of helium
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
s 3He/4He is 1.06, which indicates volcanic activity (most of the measured helium evolved from the mantle). More recent studies have confirmed these findings. The seismic activity in the region is high – in recent years there have been several earthquakes directly related to the Nemrut fault. Significant seismic events of the last 150 years that occurred within 30 km of Nemrut include the earthquakes of 18 May 1881 (magnitude 6.7), 29 March 1907 (5), 27 January 1913 (5), 14 February 1915 (6), and 3 November 1997 (5). There is evidence that the nature of volcanism in the region may change due to the shift of stress at the boundary of the Arabian and Eurasian plates. The direction of pressure coming from the Arabian plate is gradually turning from south–north to the west–east, with a linear shift of 7.8–9 mm per year. Fumarolic activity and the presence of many hot springs are observed at the bottom of the caldera.


Structure

The volcano has an elliptical shape and covers 486 km2. Its center contains 377.5 km3 of volcanic material, mainly 0.23–1.18 million years old lava. Nemrut has a distinct caldera with an area of 46.7 km2 and a volume of 32.9 km3; the maximum height of the edge of the caldera is above sea level (Sivritepe, on the 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

Lake Nemrut ( tr, Nemrut gölü) 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 A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...
. The lake is 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

Lake Ilı ( tr, Ilı gölü, "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 average is 6–8 °C warmer than expected for a lake of its altitude. Nevertheless, it partly freezes in winter because of the small size and depth.


Risk of future eruptions

Recent studies note the danger of possible eruptions. Nemrut is located in close proximity to
Tatvan Tatvan ( ) is a city on the western shore of Lake Van. It is the chief city of Tatvan District within Bitlis Province in eastern Turkey, and has about 96,000 inhabitants. The current Mayor is Mehmet Emin Geylani ( AKP). The district is fully Kurdi ...
(distance 10 km, population: 66,000),
Bitlis Bitlis ( hy, Բաղեշ '; ku, Bidlîs; ota, بتليس) is a city in southeastern Turkey and the capital of Bitlis Province. The city is located at an elevation of 1,545 metres, 15 km from Lake Van, in the steep-sided valley of the Bitlis R ...
(population 52,000),
Ahlat Ahlat ( ku, Xelat, ) is a town and district in Turkey's Bitlis Province in Eastern Anatolia Region. From 1929 to 1936, it was a district of Van Province. The town of Ahlat is situated on the northwestern shore of Lake Van. The mayor is Abdulalim M ...
(population 22,000), and a number of smaller settlements. In total, about 135,000 people live in the potential eruption zone. The presence of more than 1 km3 of water in the caldera adds a risk of flooding, which may destroy
Güroymak Güroymak ( ku, Norşîn, from hy, Նորշեն, ''Norshen'') is a town in Bitlis Province, Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located ...
, a town of 15,000 people.


Climate, flora and fauna of the caldera

The climate of the caldera is unique for the Armenian Highland. It is the only place in the region where deciduous trees grow at high altitudes, owing to the high temperature and humidity and the protection from winds by the caldera walls. The caldera also hosts a few flowers and trees unique to the region.
Velvet scoter The velvet scoter (''Melanitta fusca''), also called a velvet duck,Buczacki, Stefan (2005) ''Fauna Britannica'', Hamlyn, London. is a large sea duck, which breeds over the far north of Europe and the Palearctic west of the Yenisey basin. The genu ...
s (''Melanitta deglandi'') and two species of gull live and breed on the shores of Lake Nemrut. Since ancient times the bottom of the caldera is used for
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
by the nearby villages.


Tourism

Nemrut is considered one of the most spectacular volcanoes in the region. Its caldera can be accessed in the summer on 4x4 vehicles from the south or east side. Nemrut is covered with snow five months per year, and therefore the Turkish authorities are building a mountain ski resort and a 2,517 m long ski track on the slopes of Nemrut.


References


External links

*
Photos from Nemrut
link does not open.
Nemrut – map
{{Authority control Stratovolcanoes of Turkey Calderas of Turkey Volcanic crater lakes Mountains of Turkey Landforms of Bitlis Province Tatvan District Important Bird Areas of Turkey VEI-6 volcanoes Nimrod