| Santorini Caldera | |
|---|---|
 Santorini island group from space | |
| Highest point | |
| Coordinates | 36°23′44″N25°27′33″E / 36.39556°N 25.45917°E /36.39556; 25.45917 |
| Geography | |
 | |
| Location | Aegean Sea,Greece |
| Geology | |
| Mountain type | Caldera (active) |
| Last eruption | January to February 1950 |
Santorini caldera is a large, mostly submergedcaldera, located in the southernAegean Sea, 120 kilometers north ofCrete inGreece. Visible above water is the circular Santorini island group, consisting ofSantorini (known asThera in antiquity), the main island,Therasia andAspronisi at the periphery, and theKameni islands at the center. It has been designated aDecade Volcano.
The caldera measures about 12 by 7 km (7.5 by 4.3 mi), with 300 m (980 ft) high steep cliffs on three sides, and a maximum depth of 385 m (1,263 ft).[1]
There are two small volcanic islands at the center of the caldera,Nea ("New") Kameni andPalea ("Old") Kameni.
The main island, Santorini has an area of 75.8 km2 (29.3 sq mi), Therasia 9.3 km2 (3.6 sq mi), and the uninhabited islands of Nea Kameni 3.4 km2 (1.3 sq mi), Palea Kameni 0.5 km2 (0.19 sq mi) and Aspronisi 0.1 km2 (0.039 sq mi).
Santorini's high walls, draped by whitewashed villages, combined with a sunny climate and good observation conditions, have made it a magnet for volcanologists,[2] as well as a highlight of tourism in the Aegean.
The volcanic complex of Santorini is the most active part of theSouth Aegean Volcanic Arc, which includes the active volcanoes ofMethana on the mainland of Greece,Milos, Santorini andNisyros. It is formed by the subduction of the Africantectonic plate underneath the Aegean subplate of the Eurasian tectonic plate, which occurs at a rate of up to 5 cm per year in a northeasterly direction. This subduction causes earthquakes at depths of 150–170 km.[3]
Non-volcanic rocks are exposed on Santorini atMikro Profititis Ilias, Mesa Vouno, the Gavrillos ridge, Pirgos, Monolithos and the inner side of the caldera wall between Cape Plaka and Athinios.[4]
The Kameni islands at the center of the caldera are made of lava rocks.
The caldera of Santorini lies in the center of theChristiana-Santorini-Kolumbo volcanic field, which comprises the extinct Christiana Volcano, the Santorini Caldera, the polygenetic submarine Kolumbo Volcano, as well as the Kolumbo Volcanic Chain.[5] This volcanic lineament evolved during four main phases of volcanic activity, which initiated in the Pliocene from several local centers that only recently matured to form the vast Santorini edifice. The present-day caldera is composed of overlapping shield volcanoes, cut by at least four partially overlapping calderas, of which the oldest southern caldera was formed about 180,000 years ago. The subsequent Skaros caldera was created about 70,000 years ago, and the Cape Riva caldera about 21,000 years ago. The current caldera was formed about 3,600 years ago during theMinoan eruption.[6]
Palea Kameni and Nea Kameni were formed as a result of multiple, initially submarine, smaller eruptions at the center of the caldera.[7]
Although dormant, Santorini is an active volcano. Numerous minor and medium-sized, mainly effusive, eruptions have built the dark-colored lava shields of Nea and Palea Kameni inside the caldera.
Their last eruption was in 1950, and now onlyfumarolic activity, primarily inside the recently active craters, takes place.[2]GPS instruments registered reneweddeformation around the caldera in 2011 and 2012.[8]
The hugeMinoan eruption of Santorini in the 17th century BC may have inspired the legend ofAtlantis.[9] It was rated 7 in the Smithsonian Global Volcanism Program'sVolcanic Explosivity Index.[10]
Following is a list of the major eruptive events of Santorini beginning with the catastrophic Minoan eruption, as noted by theSmithsonian National Museum of Natural History'sGlobal Volcanism Program:[6]
| Start date | Stop date | Characteristics of eruption |
|---|---|---|
| 1610 BC ± 14 years ("Minoan eruption") | Unknown | Central vent eruption, regionalfissure eruption,submarine eruption,explosive eruption,pyroclastic flows andpyroclastic surges,phreatic explosions, extensive physical damage, massivelava fountains and extensivelava flows, minormudflows on the sea,megatsunamis, caldera collapse, fatalities, mass evacuation. |
| 197 BC | Unknown | Central vent eruption, regional fissure eruption,submarine eruption, newisland formation,explosive eruption. |
| Dec 31, 46 AD | Feb 1, 47 AD ± 30 days | Central vent eruption, regional fissure eruption, submarine eruption, newisland formation,explosive eruption, lava flows, lava dome extrusion,tsunami. |
| Jul 15 726 AD ± 45 days | Unknown | Central vent eruption, regional fissure eruption, submarine eruption, new island formation, explosive eruption,lava flows,lava dome extrusion, damage. |
| 1570 | 1573 | Central vent eruption, regional fissure eruption,submarine eruption, new island formation,explosive eruption, lava flows, lava dome extrusion. |
| Sep. 27, 1650 | Dec. 6, 1650 | Flank (excentric) vent, regional fissure eruption,submarine eruption, new island formation, explosive eruption, lava flows, fatalities, damage, tsunami. |
| May 23, 1707 | Sep. 14, 1711 | Central vent eruption, regional fissure eruption, submarine eruption, new island formation, explosive eruption, lava flows, lava dome extrusion, damage. |
| Jan. 26, 1866 | Oct. 15, 1870 | Central vent eruption, regional fissure eruption, submarine eruption, new island formation, explosive eruption, lava flows, lava dome extrusion, fatalities, damage, evacuation. |
| Aug. 11, 1925 | Mar. 17, 1928 | Central vent eruption, regional fissure eruption, explosive eruption, phreatic explosions, lava flows, lava dome extrusion. |
| Aug. 20, 1939 | Jul. 2, 1941 ± 1 day | Central vent eruption, regional fissure eruption, submarine eruption, explosive eruption, phreatic explosions, lava flows, lava dome extrusion, damage. |
| Jan. 10, 1950 | Feb. 2, 1950 | Central vent eruption, regional fissure eruption, submarine eruption, explosive eruption, phreatic explosions, lava flows, lava dome extrusion. |
In respect of it being 'one of the largest calderas in the Mediterranean Sea formed byPlinian eruptions in a volcanic arc tectonic framework', theInternational Union of Geological Sciences (IUGS) included 'The Quaternary Santorini Caldera' in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The organisation defines an IUGS Geological Heritage Site as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.'[11]
It separates the caldera into a northern and a southern basin, which have maximum depths of 385 m and 290 m, respectively.
| International | |
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| Geographic | |
