The South Aegean Volcanic Arc is a

volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc lo ...

(chain of volcanoes) in the South

Aegean Sea The Aegean Sea ; tr, Ege Denizi ( Greek: Αιγαίο Πέλαγος: "Egéo Pélagos", Turkish: "Ege Denizi" or "Adalar Denizi") is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans ...

formed by

plate tectonics 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 ...

. The prior cause was the subduction of the

African plate The African Plate is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plat ...

beneath the

Eurasian plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

, raising the Aegean arc across what is now the north

. It was not yet the sea, nor an arc, or at least not the one it is today, nor was there a chain of volcanoes. In the Holocene the process of back-arc extension began, probably stimulated by pressure from the

Arabian Plate The Arabian Plate is a minor tectonic plate in the Northern and Eastern Hemispheres. It is one of the three continental plates (along with the African and the Indian Plates) that have been moving northward in geological history and collidin ...

compressing the region behind the arc. The extension deformed the region into its current configuration. First, the arc moved to the south and assumed its arcuate configuration. Second, the Aegean Sea opened behind the arc because the crust was thinned and weakened there. Third, magma broke through the thinned crust to form a second arc composed of a volcanic chain. And finally, the Aegean Sea Plate broke away from Eurasia in the new fault zone to the north. The extension is still ongoing. The current southern Aegean is one of the most rapidly deforming regions of the Himalayan-Alpine mountain belt. It is approximately 450 km long and 20 km to 40 km wide and runs from the

Isthmus of Corinth The Isthmus of Corinth ( Greek: Ισθμός της Κορίνθου) is the narrow land bridge which connects the Peloponnese peninsula with the rest of the mainland of Greece, near the city of Corinth. The word "isthmus" comes from the Ancie ...

on the

Greek mainland Greece is a country of the Balkans, in Southeastern Europe, bordered to the north by Albania, North Macedonia and Bulgaria; to the east by Turkey, and is surrounded to the east by the Aegean Sea, to the south by the Cretan and the Libyan Seas, ...

to the

Bodrum Bodrum () is a port city in Muğla Province, southwestern Turkey, at the entrance to the Gulf of Gökova. Its population was 35,795 at the 2012 census, with a total of 136,317 inhabitants residing within the district's borders. Known in ancien ...

peninsula on the Turkish mainland.

Development of the Hellenic orogeny

The original proponent of a

convergent boundary A convergent boundary (also known as a destructive 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 ...

between Africa and Eurasia, who devised

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 ...

and

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period The Jurassic ( ) is a geologic period and st ...

land for the purpose, and invented the -ides suffix,

Eduard Suess Eduard Suess (; 20 August 1831 - 26 April 1914) was an Austrian geologist and an expert on the geography of the Alps. He is responsible for hypothesising two major former geographical features, the supercontinent Gondwana (proposed in 1861) and ...

, imagined a single great closure of Gondwana land on Eurasia, wrinkling up a mountain belt, the Altaides, that stretched from sea to sea. The simplicity and the name did not survive further scrutiny of the rocks. The mountain chain, subsequently the non-Suessian Alpides (he had his own Alpides, which amounted to the western Altaides), turned out to be the accumulation of orogenies in successive waves of advance. Not all the parallel chains derive from the same period or the same rocks. From the present, there is a virtual advance with a virtual resulting chain, but in fact the chain is mainly a composite of successive chains. The mountains of Greece, or Hellenides (viewed as a singular collective thing) appear to have had a singular origin, superficially named "the

Hellenic Orogeny The Hellenic orogeny is a collective noun referring to multiple mountain building events that shaped the topography of the southern margin of Eurasia into what is now Greece, the Aegean Sea and western Turkey, beginning in the Jurassic. Prior to ...

". These are only terms of convenience to distinguish "Hellenic" from mountains of other countries. They are actually accumulated mountain chains resulting from accumulated orogenies over time. Currently three "waves", of orogenic activity can be distinguished, resulting in three "orogenic belts". Preceding the first wave, the supercontinent,

Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...

, had already broken into

Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...

(a continuous band of Eurasia and the Americas), and

(all the rest). Between the two of them was

Paleo-Tethys Ocean The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; exi ...

. The break-up had been caused by shifting currents in the mantle. A different location of an upwelling plume placed a

divergent boundary In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent ...

in a new place, in this case across the north and east of Gondwana. The Cimmeria

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...

began to separate from Gondwana, closing Palaeo-Tethys in front of it and opening Neo-Tethys, or just plain Tethys, behind it. Cimmeria voyaged across the ocean to lodge against Eurasia, forming Cimmeria-Eurasia. The existing Cimmerides (named after the mountains of Crimea) account for the northernmost chains of the Alpides. Sometimes they are called the Hunic terranes, after the land of the

Huns The Huns were a nomadic people who lived in Central Asia, the Caucasus, and Eastern Europe between the 4th and 6th century AD. According to European tradition, they were first reported living east of the Volga River, in an area that was part ...

. They cover the Black Sea region, the northern Aegean, and the eastern part of the Balkans. Their earliest date is the "pre-

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the nam ...

". Subsequent is a two-phase Alpine Orogeny. In phase 1 (

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

) the Tethys sea floor after depositing its Cimmerian passenger against Eurasia went on to dip beneath Cimmeria-Eurasia raising up the inner (eastern) Hellenides (

Pindus The Pindus (also Pindos or Pindhos; el, Πίνδος, Píndos; sq, Pindet; rup, Pindu) is a mountain range located in Northern Greece and Southern Albania. It is roughly 160 km (100 miles) long, with a maximum elevation of 2,637 metres ...

range) and the Anatolides. Phase 2 is the arrival of another terrane, the Adriatic, or Apulian, Plate from the southwest, dipping under Cimmeria-Eurasia and raising its margin into the Dinarides and outer Hellenides in the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "da ...

and

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...

. The geologic stage was set for the latest orogenic zone, developing in the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent ...

and

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Hellenic Trench 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 begin ...

. The result was the raising of the forearc and the "exhumation" of Peloponnesus and Crete. It began to migrate to the south by back-arc extension, jutting out into the Mesogean Sea and becoming arcuate. From there the geologic story becomes more familiar, being mentioned above. The

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million yea ...

in the Aegean has been a time of faulting to adjust to the current pressures. In the Pliocene the extension had been NE–SW causing "normal high angle faults trending NW–SE". In the Quaternary the direction of extension changed to N-S with faults trending E–W. The type is predominantly strike-slip.

Volcanoes of the arc

The active portion of the South Aegean Volcanic Arc comprises a number of dormant and historically active volcanoes, including Sousaki, Aegina, Methana,

Milos Milos or Melos (; el, label=Modern Greek, Μήλος, Mílos, ; grc, Μῆλος, Mêlos) is a volcanic Greek island in the Aegean Sea, just north of the Sea of Crete. Milos is the southwesternmost island in the Cyclades group. The ''Venus ...

Santorini Santorini ( el, Σαντορίνη, ), officially Thira ( Greek: Θήρα ) and classical Greek Thera ( English pronunciation ), is an island in the southern Aegean Sea, about 200 km (120 mi) southeast from the Greek mainland. It is ...

and Kolumbo,

Kos Kos or Cos (; el, Κως ) is a Greek island, part of the Dodecanese island chain in the southeastern Aegean Sea. Kos is the third largest island of the Dodecanese by area, after Rhodes and Karpathos; it has a population of 36,986 (2021 census) ...

Nisyros Nisyros also spelled Nisiros ( el, Νίσυρος, Nísiros) is a volcanic Greek island and municipality located in the Aegean Sea. It is part of the Dodecanese group of islands, situated between the islands of Kos and Tilos. Its shape is app ...

and Yali, and Akyarlar. Of these, only Santorini, Kolumbo and Nisyros have either erupted or shown any significant evidence of unrest during the past 100 years. One of the most noted

volcanic eruption Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are oft ...

s from this arc occurred on the island of Santorini in the

second millennium BC The 2nd millennium BC spanned the years 2000 BC to 1001 BC. In the Ancient Near East, it marks the transition from the Middle to the Late Bronze Age. The Ancient Near Eastern cultures are well within the historical era: The first half of the mi ...

; during the catastrophic volcanic eruption of Santorini, the

Bronze Age The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second pr ...

city of Akrotiri was destroyed, with archaeological remains becoming well preserved under the volcanic ash.Hogan, C. Michael (2007)
"Akrotiri"
The Modern Antiquarian.

Citations

General and cited references

External links

* {{commonscat-inline Aegean Sea Volcanic arcs Volcanoes of Greece Volcanoes of Turkey

Development of the Hellenic orogeny

Volcanoes of the arc

See also

Citations

General and cited references

External links