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The geology of Turkey is the product of a wide variety of tectonic processes that have shaped Anatolia over millions of years, a process which continues today as evidenced by frequent earthquakes and occasional volcanic eruptions.
Turkey's terrain is structurally complex. A central massif composed of uplifted blocks and downfolded troughs, covered by recent deposits and giving the appearance of a plateau with rough terrain, is wedged between two folded mountain ranges that converge in the east. True lowland is confined to the plain of the Ergene river in Thrace, extending along rivers that discharge into the Aegean Sea or the Sea of Marmara, and to a few narrow coastal strips along the Black Sea and Mediterranean Sea coasts.[ citation needed ]
Nearly 85% of the land is at an elevation of at least 450 meters; the median altitude of the country is 1,128 meters. In Asiatic Turkey, flat or gently sloping land is rare and largely confined to the deltas of the Kızıl River, the coastal plains of Antalya and Adana, and the valley floors of the Gediz River and the Büyük Menderes River, and some interior high plains in Anatolia, mainly around Tuz Gölü (Salt Lake) and Konya Ovası (Konya Basin). Moderately sloping terrain is limited almost entirely outside Thrace to the hills of the Arabian Platform along the border with Syria.
More than 80% of the land surface is rough, broken, and mountainous, and therefore is of limited agricultural value. The terrain's ruggedness is accentuated in the eastern part of the country, where the two mountain ranges converge into a lofty region with a median elevation of more than 1,500 meters, which reaches its highest point along the borders with Armenia, Azerbaijan, and Iran. Turkey's highest peak, Mount Ararat (Ağrı Dağı)—about 5,166 meters high—is situated near the point where the boundaries of the four countries meet.
The earliest geological history of Turkey is poorly understood, partly because these oldest rocks in the region are involved into younger deformation phases that hindered their evolution. This created problem of reconstructing how the region has been tectonically assembled by plate motions. Turkey can be thought of as a collage of different continental pieces and remnants of oceanic lithospheric rocks amalgamated together by younger tectonic processes that involve accumulation of igneous (both plutonic and volcanic) and sedimentary rocks.
Except for a relatively small portion of its territory along the Syrian border that is a continuation of the Arabian Plate, Turkey geologically is part of the great Alpide belt that extends from the Atlantic Ocean to the Himalaya Mountains. This belt was formed during the Cenozoic Era (about 66 to 1.6 million years ago), as the Arabian, African, and Indian continental plates began to collide with the Eurasian Plate. This process is still at work today as the African Plate converges with the Eurasian Plate and the Anatolian Plate escapes towards the west and southwest along strike-slip faults. These are the North Anatolian Fault Zone, which forms the present day plate boundary of Eurasia near the Black Sea coast and, the East Anatolian Fault Zone, which forms part of the boundary of the North Arabian Plate in the southeast. As a result of this plate tectonics configuration, Turkey is one of the world's more active earthquake and volcanic regions. [1]
The Anatolian Plate, together with the Aegean-Peloponnesus block, is located near the centre of a very wide region, including the Arabian Plate with the adjacent Zagros Mountains and central Iran, that moves in a circulatory pattern at a relatively fast rate of 20 mm/yr. The rate of this counter-clockwise motion increases near the Hellenic Trench system south of Turkey and decreases away from it (i.e. the Eurasian and African plates move at a rate of 5 mm/yr), resulting in internal deformations in several areas, including central and eastern Anatolia, south-western Aegean-Peloponnesus, Lesser Caucasus, and central Iran. The dominant process in the region is the subduction of the African Plate beneath the Hellenic Trench, and the deformation in the entire African-Arabian-Eurasian collision zone is most likely driven by the slab roll-back of the subducting African Plate in the East Mediterranean. [2] This process is further fuelled by slab-pull forces in the Makran Trench in the Gulf of Oman where the Arabian Plate is subducting under Eurasia. A response to this tectonic maelstrom is the rifting in the Red Sea and Gulf of Aden which will separate Arabia from Africa. [3]
The tomography of the velocity propagation distributions of the P_n seismic waves both in an isotropic and anisotropic conditions, compared with the lateral variations of that velocity has highlighted the physical properties of the uppermost mantle and crustal thickness of the Earth. A study analyzed 700 earthquakes occurred in Turkey from 1999 to 2010 with magnitude degree major than 4.0 and the related 50.000 Pn first arrivals recorded by 832 seismic stations at a distance range of 180–1500 km from the epicenter. The tomography highlighted that "Pn velocities are found to be lowest in eastern Turkey (<7.6 km s-1) and highest in the eastern Mediterranean Sea and Zagros Suture (>8.3 km s-1). Large Pn anisotropy is observed in the Aegean, central Anatolia and along the southern coast of Anatolia. [...] Large crustal thicknesses are observed along the Dinarides-Hellenides and along the southern coast of Anatolia." [4]
Many of the rocks exposed in Turkey were formed long before this process began. Turkey contains outcrops of Precambrian rocks, (more than 540 million years old). [5]
During the Mesozoic era (about 250 to 66 million years ago) a large ocean (Tethys Ocean), floored by oceanic lithosphere existed in-between the supercontinents of Gondwana and Laurasia (which lay to the south and north respectively). [6] This large oceanic plate was consumed at subduction zones. At the subduction trenches the sedimentary rock layers that were deposited within the prehistoric Tethys Ocean were folded, faulted and tectonically mixed with huge blocks of crystalline basement rocks of the oceanic lithosphere. These blocks form a very complex mixture or mélange of rocks that include mainly serpentinite, basalt, dolerite, and chert. [7] The Eurasian margin, now preserved in the Pontides (the Pontic Mountains along the Black Sea coast), is thought to have been geologically similar to the Western Pacific region today. [8] Volcanic arcs and back-arc basins formed and were emplaced onto Eurasia as ophiolites as they collided with microcontinents (literally relatively small plates of continental lithosphere). [9] These microcontinents had been pulled away from the Gondwanan continent further south. Turkey is therefore made up from several different prehistorical microcontinents.[ citation needed ]
During the Cenozoic (Tertiary about 66 to 1.6 million years) folding, faulting and uplifting, accompanied by volcanic activity and intrusion of igneous rocks was related to major continental collision between the larger Arabian and Eurasian plates. [10]
Turkey's most severe earthquake in the twentieth century occurred in Erzincan on the night of 1939-12-27; it devastated most of the city and caused an estimated 30,000 deaths. Earthquakes of moderate intensity often continue with sporadic aftershocks over periods of several days or even weeks. Seismicity in Turkey is more likely to happen in the North Anatolian Fault Zone, East Anatolian Fault Zone and in the subduction region of the Aegean Plate between the Anatolian plate.
The Anatolian side of Turkey is the largest portion in the country that bridges southeastern Europe and west Asia. East Thrace, the European portion of Turkey comprises 3% of the country and 10% of its population. East Thrace is separated from Asia Minor, the Asian portion of Turkey, by the Bosporus, the Sea of Marmara and the Dardanelles. İskilip, Çorum province, is considered to be the geographical center of Earth. Turkey has the 17th longest coastline in the world with 7,200 km.
A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.
The African Plate, also known as the Nubian Plate, is a major tectonic plate that includes much of the continent of Africa and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate to the west ; the Arabian Plate and Somali Plate to the east; the Eurasian Plate, Aegean Sea Plate and Anatolian Plate to the north; and the Antarctic Plate to the south.
The Arabian Plate is a minor tectonic plate in the Northern and Eastern Hemispheres.
The Anatolian Plate is a continental tectonic plate that is separated from the Eurasian plate and the Arabian plate by the North Anatolian Fault and the East Anatolian Fault respectively. Most of the country of Turkey is located on the Anatolian plate. Most significant earthquakes in the region have historically occurred along the northern fault, such as the 1939 Erzincan earthquake. The devastating 2023 Turkey–Syria earthquake occurred along the active East Anatolian fault at a strike slip fault where the Arabian plate is sliding past the Anatolian plate horizontally.
Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthquakes are the planet's most powerful, with moment magnitudes (Mw) that can exceed 9.0. Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes.
The islands of Japan are primarily the result of several large ocean movements occurring over hundreds of millions of years from the mid-Silurian to the Pleistocene, as a result of the subduction of the Philippine Sea Plate beneath the continental Amurian Plate and Okinawa Plate to the south, and subduction of the Pacific Plate under the Okhotsk Plate to the north.
Cimmeria was an ancient continent, or, rather, a string of microcontinents or terranes, that rifted from Gondwana in the Southern Hemisphere and was accreted to Eurasia in the Northern Hemisphere. It consisted of parts of present-day Turkey, Iran, Afghanistan, Pakistan, Tibet, China, Myanmar, Thailand, and Malaysia. Cimmeria rifted from the Gondwanan shores of the Paleo-Tethys Ocean during the Early Permian and as the Neo-Tethys Ocean opened behind it, during the Permian, the Paleo-Tethys closed in front of it. Because the different chunks of Cimmeria drifted northward at different rates, a Meso-Tethys Ocean formed between the different fragments during the Cisuralian. Cimmeria rifted off Gondwana from east to west, from Australia to the eastern Mediterranean. It stretched across several latitudes and spanned a wide range of climatic zones.
An accretionary wedge or accretionary prism forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust, but in some cases the wedge includes the erosional products of volcanic island arcs formed on the overriding plate.
The Aegean Sea Plate is a small tectonic plate located in the eastern Mediterranean Sea under southern Greece and western Turkey. Its southern edge is the Hellenic subduction zone south of Crete, where the African Plate is being swept under the Aegean Sea Plate. Its northern margin is a divergent boundary with the Eurasian Plate.
This is a list of articles related to plate tectonics and tectonic plates.
In the geology of the Philippines, the Philippine Mobile Belt is a complex portion of the tectonic boundary between the Eurasian Plate and the Philippine Sea Plate, comprising most of the country of the Philippines. It includes two subduction zones, the Manila Trench to the west and the Philippine Trench to the east, as well as the Philippine Fault System. Within the Belt, a number of crustal blocks or microplates which have been shorn off the adjoining major plates are undergoing massive deformation.
The Hellenic Trench (HT) is an oceanic trough located in the forearc of the Hellenic Arc, an arcuate archipelago on the southern margin of the Aegean Sea Plate, or Aegean Plate, also called Aegea, the basement of the Aegean Sea. The HT begins in the Ionian Sea near the mouth of the Gulf of Corinth and curves to the south, following the margin of the Aegean Sea. It passes close to the south shore of Crete and ends near the island of Rhodes just offshore Anatolia.
The Hellenic arc or Aegean arc is an arcuate mountain chain of the southern Aegean Sea located on the southern margin of the Aegean Sea Plate. Geologically it results from the subduction of the African Plate under it along the Hellenic subduction zone. The Hellenic Trench trends parallel to its southern side. The Aegean Sea Plate, a microplate, is often considered part of the Eurasian Plate from which it is in the process of diverging. The arc itself is mainly marine, the mountaintops appearing as islands in the Ionian Sea, Crete and its environs, or in the Dodecanese group. It encroaches on mainland terrain in the Peloponnesus, on Crete, on Rhodes, and on the southern coast of Anatolia, thus being encompassed by both Greece and Turkey.
In 21 July 2017, a large earthquake measuring 6.6 on the moment magnitude scale struck right near Bodrum, a popular town of tourism in Turkey, killing 2 and injuring hundreds. Mostly referenced as the 2017 Bodrum–Kos earthquake, this earthquake generated a tsunami which was one of the largest tsunamis in the Mediterranean Sea region.
The geology of Iraq includes thick sequences of marine and continental sedimentary rocks over poorly understood basement rock, at the junction of the Arabian Plate, the Anatolian Plate, and the Iranian Plate.
The subduction tectonics of the Philippines is the control of geology over the Philippine archipelago. The Philippine region is seismically active and has been progressively constructed by plates converging towards each other in multiple directions. The region is also known as the Philippine Mobile Belt due to its complex tectonic setting.
The Hellenic subduction zone (HSZ) is the convergent boundary between the African Plate and the Aegean Sea Plate, where oceanic crust of the African is being subducted north–northeastwards beneath the Aegean. The southernmost and shallowest part of the zone is obscured beneath the deformed thick sedimentary sequence that forms the Mediterranean Ridge accretionary complex. It has a well-defined Wadati–Benioff zone of seismicity, which demonstrates the relatively shallow dip of its southern part, which increases markedly to the north of the non-volcanic part of the Hellenic arc. The descending slab has been imaged using seismic tomography down to the top of the mantle transition zone at 410 km depth.
The 479 BC Potidaea tsunami is the oldest record of a paleotsunami in human history. The tsunami is believed to have been triggered by a Ms 7.0 earthquake in the north Aegean Sea. The associated tsunami may have saved the colony of Potidaea from an invasion by Persians from the Achaemenid Empire.
This article incorporates text from this source, which is in the public domain . Country Studies. Federal Research Division. This article incorporates public domain material from The World Factbook. CIA.
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