Hellenic island arch

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Map of the Hellenic island arc with the main tectonic units.

The Hellenic island arc or Aegean island arc , English Hellenic Arc , is in the eastern Mediterranean location island arc structure resulting from the subduction of the African plate under the Aegean plate emerged. The north-east-south-west relative movement of the two plates takes place at a speed of 50 millimeters per year. Which lies on the outer side of the island arc in the direction of Africa Hellenic deep ditch , caused by the subduction Tiefseerinne . On the inside there are two separate arches - a non-volcanic outer and a volcanic inner arch, the Cycladic Arch . The north adjoining Aegean Sea forms a marginal sea on the inside of the arch of the island .

Geographical expansion

The Hellenic Arch of the Islands extends from the Ionian Islands in the west of Greece to Rhodes in the east, where it joins the Arch of Cyprus .

Hellenic deep sea trench

The Hellenic abyss , even Cretan abyss (Engl. Hellenic Trench ), is not the topographic expression of the actual subduction zone, but rather forms the sedimentuntersättigten section of the fore-arc basin . The Mediterranean back (engl. Mediterranean Ridge ) which demarcates the south side of this Tiefseerinne is a running along on the frontal subduction accretionary wedge . The northern border of the Mediterranean ridge to the deep sea trench is marked by a significant back thrust. The Hellenic Deep Sea Trench is most clearly formed in the western part of the arch structure, further to the east it divides into the Pliny and Strabograben .

The Hellenic Rift is created by the collision between the Eurasian and African continental plates . The latter forms a large part of the bottom of the Ionian Sea between Sicily and southern Italy in the west and the Ionian Islands and mainland Greece in the east. Earthquakes occur repeatedly due to the tension between the colliding continental plates. Another consequence of the plate collision is the Hellenic rift as a deepening of the earth's crust , which reaches depths of up to 5,000 m in the Ionian Sea to the west, southwest and south of Zakynthos and is one of the deepest places in the Mediterranean.

Non-volcanic arch

The non-volcanic arch, also non- volcanic Kretischer Bogen (English Outer Non-Volcanic Arc ), represents a topographically high-lying zone that can be followed over the entire length of the arch . At the sections that rise above sea level, it forms the Ionian Islands, Crete and Rhodes. It is the raised part of the Forearcs and the eastward continuation of the Ionian Zone of the Hellenids on the Greek mainland.

Cycladic Arch

The volcanic Cycladic Arc ( Inner Volcanic Arc or South Aegean Volcanic Arc ) located on the inside, 20 to 40 kilometers wide, extends over 450 kilometers from Methana on the east coast of the Peloponnese to Nisyros and Bodrum on the Turkish coast. It is built up from a series of volcanic islands that have come to rest or are still active - such as Santorini , the focus of the catastrophic Minoan eruption of 1620/1520 BC. BC, also Aegina , Milos , Gyali and Kos . Andesites , dazites and rhyolites were funded .

Geodynamic development

The current geometric arrangement of the Hellenic island arc is due to the southward migration of the subduction zone . This southward shift caused a stretch both parallel and perpendicular to the strike direction of the island arc.

Seismics

The Hellenic Arch is one of the most active earthquake zones in western Eurasia . Earthquakes of magnitude 7 have been measured here regularly over the past hundred years of seismic instrumentation. Two historical quakes, the earthquake off Crete 365 and the earthquake off Crete 1303 , even reached magnitude 8.

literature

Volker Jacobshagen : Geology of Greece . 1986.

Individual evidence

  1. ↑ David M. Pyle and John R. Elliott: Quantitative morphology, recent evolution, and future activity of the Kameni islands volcano, Santorini, Greece . In: Geosphere . 36, No. 2, 2006, pp. 253-268 .
  2. ↑ Stern, RJ: Ocean Trenches. Earth Processes . Elsevier, 2004.
  3. ↑ Chamot-Rooke, N., Rabaute, A. and Kreemer, C .: Western Mediterranean Ridge mud belt correlates with active shear strain at the prism-backstop geological contact . In: Geology . tape 33 (11) , 2005, pp. 861-864 , doi : 10.1130 / G21469.1 .
  4. ^ Hellenic Trench - Marine Mammal Protected Areas Task Force . Marine Mammal Protected Areas Task Force. November 2013.
  5. ↑ ten Veen, JH and Kleinspehn, KL: Incipient continental collision and plate-boundary curvature: Late Pliocene – Holocene transtensional Hellenic forearc, Crete, Greece . In: Journal of the Geological Society . tape 160 (2) , 2003, p. 161-181 , doi : 10.1144 / 0016-764902-067 .
  6. ↑ Papadopoulos, GA, Ganas, A. and Karastathis, C .: Seismicity Properties as a Marker of the Active Plate Convergence in the western Hellenic Arc . American Geophysical Union, Fall Meeting Abstracts 53: 0483, 2004.

Coordinates: 37 ° 43 '  N , 25 ° 17'  E