Santorini caldera
Encyclopedia
Santorini caldera is a large, mostly submerged caldera, located in the southern Aegean Sea
, 120 kilometers north of Crete
in Greece. Visible above water is the circular Santorini island
group, consisting of Santorini
(aka Thera), the main island, Therasia
and Aspronisi at the periphery, and the Kameni islands
at the center.
There are two small volcanic islands at the center of the caldera, Nea ("New") Kameni
and Palea ("Old") Kameni.
The main island, Santorini has an area of 75.8 km² (29.3 sq mi) km2, 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 (0.193051079296268 sq mi) and Aspronisi 0.1 km² (0.0386102158592535 sq mi).
The extraordinary beauty of Santorini's high walls, draped by whitewashed villages, combined with a sunny climate and perfect observation conditions, have made it a magnet for volcanologists, as well as a highlight of tourism in the Aegean.
, which includes the volcanoes of Methana
, Milos
, Santorini and Nisyros
. It marks the subduction of the African tectonic plate underneath the Aegean subplate of the Eurasian tectonic plate, at a rate of up to 5 cm per year in a northeasterly direction. It is characterized by earthquakes at depths of 150–170 km.
Non-volcanic rocks are exposed on Santorini at the Profitis Ilias Mountain, Mesa Vouno, the Gavrillos ridge, Pirgos, Monolithos and the inner side of the caldera wall between Cape Plaka and Athinios.
The Kameni islands at the center of the caldera are made of lava rocks.
(BP). The subsequent Skaros caldera was created about 70,000 years BP, and the Cape Riva caldera about 21,000 years BP. The current caldera was formed about 3600 years BP during the Minoan eruption.
Palea Kameni and Nea Kameni were formed as a result of multiple, initially submarine eruptions at the center of the caldera.
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 only fumarolic activity, primarily inside the recently active craters, takes place.
The huge Minoan eruption of Santorini in the 17th century BC was rated 7, the highest score for a historical eruption, in the Smithsonian Global Volcanism Program's Volcanic Explosivity Index
.
:
Aegean Sea
The Aegean Sea[p] is an elongated embayment of the Mediterranean Sea located between the southern Balkan and Anatolian peninsulas, i.e., between the mainlands of Greece and Turkey. In the north, it is connected to the Marmara Sea and Black Sea by the Dardanelles and Bosporus...
, 120 kilometers north of Crete
Crete
Crete is the largest and most populous of the Greek islands, the fifth largest island in the Mediterranean Sea, and one of the thirteen administrative regions of Greece. It forms a significant part of the economy and cultural heritage of Greece while retaining its own local cultural traits...
in Greece. Visible above water is the circular Santorini island
Santorini
Santorini , officially Thira , is an island located in the southern Aegean Sea, about southeast from Greece's mainland. It is the largest island of a small, circular archipelago which bears the same name and is the remnant of a volcanic caldera...
group, consisting of Santorini
Santorini
Santorini , officially Thira , is an island located in the southern Aegean Sea, about southeast from Greece's mainland. It is the largest island of a small, circular archipelago which bears the same name and is the remnant of a volcanic caldera...
(aka Thera), the main island, Therasia
Therasia
Therasia, also known as Thirasía , is an island in the volcanic island group of Santorini in the Greek Cyclades. It lies north-west of Nea Kameni, a small island formed in recent centuries by volcanic activity and thus marking the centre of the island group...
and Aspronisi at the periphery, and the Kameni islands
Nea Kameni
Nea Kameni is a small uninhabited Greek island of volcanic origin located in the Aegean Sea within the flooded Santorini caldera. Nea Kameni and the neighbouring small island Palea Kameni have formed over the past two millennia by repeated eruptions of dacite lava and ash...
at the center.
Geography
The caldera measures about 12 by, with 300 m (984.3 ft) high steep cliffs on three sides.There are two small volcanic islands at the center of the caldera, Nea ("New") Kameni
Nea Kameni
Nea Kameni is a small uninhabited Greek island of volcanic origin located in the Aegean Sea within the flooded Santorini caldera. Nea Kameni and the neighbouring small island Palea Kameni have formed over the past two millennia by repeated eruptions of dacite lava and ash...
and Palea ("Old") Kameni.
The main island, Santorini has an area of 75.8 km² (29.3 sq mi) km2, 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 (0.193051079296268 sq mi) and Aspronisi 0.1 km² (0.0386102158592535 sq mi).
The extraordinary beauty of Santorini's high walls, draped by whitewashed villages, combined with a sunny climate and perfect observation conditions, have made it a magnet for volcanologists, as well as a highlight of tourism in the Aegean.
Geology
The volcanic complex of Santorini is the most active part of the South Aegean Volcanic ArcSouth Aegean Volcanic Arc
The South Aegean Volcanic Arc is a chain of volcanic islands in the South Aegean Sea formed by plate tectonics as a consequence of the subduction of the African tectonic plate beneath the Eurasian plate...
, which includes the volcanoes of Methana
Methana
Methana is a town and a former municipality on the Peloponnese peninsula, Greece. Since the 2011 local government reform it is part of the municipality Troizinia, of which it is a municipal unit....
, Milos
Milos
Milos , is a volcanic Greek island in the Aegean Sea, just north of the Sea of Crete...
, Santorini and Nisyros
Nisyros
Nisyros 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 approximately round, with a diameter of about , and an area of . Several other islets are found in the direct...
. It marks the subduction of the African tectonic plate underneath the Aegean subplate of the Eurasian tectonic plate, at a rate of up to 5 cm per year in a northeasterly direction. It is characterized by earthquakes at depths of 150–170 km.
Non-volcanic rocks are exposed on Santorini at the Profitis Ilias Mountain, Mesa Vouno, the Gavrillos ridge, Pirgos, Monolithos and the inner side of the caldera wall between Cape Plaka and Athinios.
The Kameni islands at the center of the caldera are made of lava rocks.
Volcanology
The 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 before the present eraBefore Present
Before Present years is a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use AD 1950 as the origin of the age scale, reflecting the fact that radiocarbon...
(BP). The subsequent Skaros caldera was created about 70,000 years BP, and the Cape Riva caldera about 21,000 years BP. The current caldera was formed about 3600 years BP during the Minoan eruption.
Palea Kameni and Nea Kameni were formed as a result of multiple, initially submarine eruptions at the center of the caldera.
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 only fumarolic activity, primarily inside the recently active craters, takes place.
The huge Minoan eruption of Santorini in the 17th century BC was rated 7, the highest score for a historical eruption, in the Smithsonian Global Volcanism Program's Volcanic Explosivity Index
Volcanic Explosivity Index
The Volcanic Explosivity Index was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions....
.
Eruptive history
Following is a list of the major eruptive events of Santorini beginning with the catastropic Minoan eruption, as noted by the Smithsonian National Museum of Natural History's Global Volcanism ProgramGlobal Volcanism Program
The Smithsonian Institution's Global Volcanism Program documents Earth's volcanoes and their eruptive history over the past 10,000 years. The GVP reports on current eruptions from around the world as well as maintaining a database repository on active volcanoes and their eruptions. In this way, a...
:
Start date | Stop date | Characteristics of eruption |
1610 BC ± 14 years | Unknown | Central vent eruption, regional fissure Fissure vent A fissure vent, also known as a volcanic fissure or simply fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is usually a few meters wide and may be many kilometers long. Fissure vents can cause large flood basalts and lava channels... eruption, submarine eruption, explosive eruption Explosive eruption An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the... , pyroclastic flow Pyroclastic flow A pyroclastic flow is a fast-moving current of superheated gas and rock , which reaches speeds moving away from a volcano of up to 700 km/h . The flows normally hug the ground and travel downhill, or spread laterally under gravity... s, phreatic explosions, fatalities, extensive physical damage, mudflows, tsunami Tsunami A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake... , caldera collapse, evacuation. |
197 BC | Unknown | Central vent eruption, regional fissure eruption, submarine eruption, new island Island An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm... formation, explosive eruption. |
Dec 31, 46 AD | Feb 1, 47 AD ± 30 days | Central vent eruption, regional fissure eruption, submarine eruption, new island formation, explosive eruption, lava flows, lava dome Lava dome |250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano... 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. |