Geography Santorini volcano is located about 120 km north of the island Crete. Santorini is in the South Aegean volcanic arc. This volcanic arc extends from the mainland of Greece to the Bodrum peninsula in Turkey SANTORINI VOLCANO, AEGEAN ARC Tectonic Santorini lies in an area of a very complex extensional and subduction related tectonics in a continental environment. In simple clarification, the African plate is is being subducted into the mantle as it moves northward and converges on the Eurasian plate at a rate up to five centimeters per year. Prehistoric eruptions Volcanism began in the area of Santorini about 2 million years ago with the extrusion of dacitic lavas from vents in the area where Akrotiri peninsula is to day and continued to produce different kinds of lavas and pyroclasts. There have been 12 major pyroclastic eruptions. In the last 200.000 years the activity has been characteristict of cyclic construction of shield volcanoes interrupted by large explosive and destructive events who has generated calderas, this has happened at least four times. The latest big event happend in 1650 B.C. and it was the largest event in the last 10.000 years, named the Minoan eruption. About 30 km3 of rhyodacite magma was erupted and the plinian column was about 36 km high. Historic eruptions To day there are only few remaining volanoes and they are grouped around a large bay. The large central basin or caldera is divided into the three remaining parts og the older ring-island, Thera, Therasia and Aspronisi. In the caldera, historical volcanism at Santorini has built Palaea Kameni and Nea Kameni. Construction of the islands probably began soon after the Minoan eruption. The volcano islands broke the surface in 197 B.C. and has erupted about 9 times since, latest in 1950. The Kameni islands are slowly filling the caldera and probably leading to another col- lapse of the caldera. The eruption in 1950 The eruption of 1950 consisted of phreatic explosions and small extru- sions of viscous lava. The “Reck dome” dissapeared, leaving only a huge funnel-shaped depression. This probably happened when a strong explo- sion was heard from Nea Kameni. The eruption lasted less than a month and it constructed a dome. Petrological characteristics Sedimentary an volcanic deposits of all col- ors have given Santorini beautiful appear- ance. There is a volcanic carapace of lavas, slag and ash mantles and core of ancient metamorphosed sediments. The petrology of Santorini range in compositon from basalt rhyodacite and rare rhyolite. Monitoring Measurements of small variations of the local graviational field are being conducted by IGME from Athens in collaboration with the Geological and Geophysical Institude of the University of Athens.Leveling points have been measured regularly to detect changes in the state of the volcano. Scien- tists have also been monitoring seismic activity. References 1. Sigurdsson, Haraldur (Editor-in-chief), Bruce Houghton, Stephen R. McNutt, Hazel Rymer & John Stix (all associate editors). 2000. Encyclopedia of Volcanoes, Academic Press, California, USA, 2. Friedrich, Walter L. (translatet by A. R. McBirney). 2000. Fire in the Sea, The Santorini Volcano: Natural History and the Legend of Atlantis. Cambridge University Press. 3. Druitt, T. H., Edwards, L., Mellosrs, R. M., Pyle, D. M., Sparks, R. S. J., Landphere, M., Davies, M. & Barreiro, B. 1999. Santorini Volcano. Geological society, London, Mermoirs, 19. Sigurjón Valgeir Hafsteinsson

Geography - University of Iceland · Geography Santorini volcano is located about 120 km north of the island Crete. Santorini is in the South Aegean volcanic arc. This volcanic arc

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Page 1: Geography - University of Iceland · Geography Santorini volcano is located about 120 km north of the island Crete. Santorini is in the South Aegean volcanic arc. This volcanic arc

SANTORINI VOLCANO, AEGEAN ARC

TectonicSantorini lies in an area of a very complex extensional andsubduction related tectonics in a continental environment. Insimple clarification, the African plate is is being subductedinto the mantle as it moves northward and converges on theEurasian plate at a rate up to five centimeters per year.

Prehistoric eruptionsVolcanism began in the area of Santorini about 2 million years ago with theextrusion of dacitic lavas from vents in the area where Akrotiri peninsula is today and continued to produce different kinds of lavas and pyroclasts. Therehave been 12 major pyroclastic eruptions.In the last 200.000 years the activity has been characteristict of cyclic con-struction of shield volcanoes interrupted by large explosive and destructiveevents who has generated calderas, this has happened at least four times.The latest big event happend in 1650 B.C. and it was the largest event in thelast 10.000 years, named the Minoan eruption. About 30 km3 of rhyodacitemagma was erupted and the plinian column was about 36 km high.

Historic eruptionsTo day there are only few remaining volanoes and they are groupedaround a large bay. The large central basin or caldera is divided into thethree remaining parts og the older ring-island, Thera, Therasia andAspronisi. In the caldera, historical volcanism at Santorini has built PalaeaKameni and Nea Kameni. Construction of the islands probably begansoon after the Minoan eruption. The volcano islands broke the surface in197 B.C. and has erupted about 9 times since, latest in 1950. The Kameniislands are slowly filling the caldera and probably leading to another col-lapse of the caldera.

The eruption in 1950The eruption of 1950 consisted of phreatic explosions and small extru-sions of viscous lava. The “Reck dome” dissapeared, leaving only a hugefunnel-shaped depression. This probably happened when a strong explo-sion was heard from Nea Kameni. The eruption lasted less than a monthand it constructed a dome.

Petrological characteristicsSedimentary an volcanic deposits of all col-ors have given Santorini beautiful appear-ance. There is a volcanic carapace of lavas,slag and ash mantles and core of ancientmetamorphosed sediments. The petrologyof Santorini range in compositon from basaltrhyodacite and rare rhyolite.

MonitoringMeasurements of small variations of thelocal graviational field are being conductedby IGME from Athens in collaboration withthe Geological and Geophysical Institude ofthe University of Athens.Leveling pointshave been measured regularly to detectchanges in the state of the volcano. Scien-tists have also been monitoring seismicactivity.

References1. Sigurdsson, Haraldur (Editor-in-chief), Bruce Houghton, Stephen R. McNutt, HazelRymer & John Stix (all associate editors). 2000. Encyclopedia of Volcanoes, Academic Press,California, USA,2. Friedrich, Walter L. (translatet by A. R. McBirney). 2000. Fire in the Sea, The SantoriniVolcano: Natural History and the Legend of Atlantis. Cambridge University Press.3. Druitt, T. H., Edwards, L., Mellosrs, R. M., Pyle, D. M., Sparks, R. S. J., Landphere, M.,Davies, M. & Barreiro, B. 1999. Santorini Volcano. Geological society, London, Mermoirs, 19. Sigurjón Valgeir Hafsteinsson