Minoan eruption

The Minoan eruption was a catastrophic volcanic eruption that devastated the Aegean island of Thera (also called Santorini) circa 1600 BCE. It destroyed the Minoan settlement at Akrotiri, as well as communities and agricultural areas on nearby islands and the coast of Crete with subsequent earthquakes and tsunamis. With a VEI magnitude between 6 and 7, resulting in an ejection of approximately of dense-rock equivalent (DRE), the eruption was one of the largest volcanic events on Earth in human history. Since tephra from the Minoan eruption serves as a marker horizon in nearly all archaeological sites in the Eastern Mediterranean, its precise date is of high importance and has been fiercely debated among archaeologists and volcanologists for decades, without coming to a definite conclusion.

Although there are no clear ancient records of the eruption, its plume and volcanic lightning may have been described in the Egyptian Tempest Stele. The Chinese '' Bamboo Annals'' reported unusual yellow skies and summer frost at the beginning of the Shang dynasty, which may have been a consequence of volcanic winter (similar to 1816, the Year Without a Summer, after the 1815 eruption of Mount Tambora).

Eruption

Background

Geological evidence shows the Thera volcano erupted numerous times over several hundred thousand years before the Minoan eruption. In a repeating process, the volcano would violently erupt, then eventually collapse into a roughly circular seawater-filled caldera, with numerous small islands forming the circle. The caldera would slowly refill with magma, building a new volcano, which erupted and then collapsed in an ongoing cyclical process.

Immediately before the Minoan eruption, the walls of the caldera formed a nearly continuous ring of islands, with the only entrance between Thera and the tiny island of Aspronisi. This cataclysmic eruption was centered on a small island just north of the existing island of Nea Kameni in the centre of the then-existing caldera. The northern part of the caldera was refilled by the volcanic ash and lava, then collapsed again.

Magnitude

Research by a team of international scientists in 2006 revealed that the Santorini event was much larger than the original estimate of of dense-rock equivalent (DRE) that was published in 1991. With an estimated DRE in excess of , the volume of ejecta was approximately . If so, the eruption's Volcanic Explosivity Index was 7. Very thick submarine pyroclastic flow deposits of the Minoan eruption, estimated at , have been mapped on the seafloor at distances up to 30 km around the volcano, i.e. up to four times as much as produced by the well-recorded eruption of Krakatoa in 1883. The Thera volcanic events and subsequent ashfall probably destroyed all indigenous life, as was observed on Krakatoa. Only the Mount Tambora volcanic eruption of 1815, Mount Samalas eruption of 1257, Lake Taupo's Hatepe eruption around 180 CE, and perhaps the Paektu Mountain eruption of 946 CE released more material into the atmosphere during historic times.

Sequence

On Santorini, there is a thick layer of white tephra that overlies the soil clearly delineating the ground level before the eruption. This layer has three distinct bands that indicate the different phases of the eruption. Studies have identified four major eruption phases, and one minor precursory tephra fall. The thinness of the first ash layer, along with the lack of noticeable erosion of that layer by winter rains before the next layer was deposited, indicate that the volcano gave the local population a few months' warning. Since no human remains have been found at the Akrotiri site, this preliminary volcanic activity probably caused the island's population to flee. It is also suggested that several months before the eruption, Santorini experienced one or more earthquakes, which damaged the local settlements.

Intense magmatic activity of the first major phase (BO₁/Minoan A) of the eruption deposited up to of pumice and ash, with a minor lithic component, southeast and east. Archaeological evidence indicated burial of man-made structures with limited damage. The second (BO₂/Minoan B) and third (BO₃/Minoan C) eruption phases involved pyroclastic surges and lava fountaining, as well as the possible generation of tsunamis. Man-made structures not buried during Minoan A were completely destroyed. The third phase was also characterized by the initiation of caldera collapse. The fourth, and last, major phase (BO₄/Minoan D) was marked by varied activity: lithic-rich base surge deposits, lava flows, lahar floods, and co- ignimbrite ash-fall deposits. This phase was characterized by the completion of caldera collapse, which produced megatsunamis.

Geomorphology

Although the fracturing process is not yet known, the altitudinal statistical analysis indicates that the caldera had formed just before the eruption. The area of the island was smaller, and the southern and eastern coastlines appeared regressed. During the eruption, the landscape was covered by the pumice sediments. In some places, the coastline vanished under thick tuff depositions. In others, recent coastlines were extended towards the sea. After the eruption, the geomorphology of the island was characterized by an intense erosional phase during which the pumice was progressively removed from the higher altitudes to the lower ones.

Volcanology

The eruption was of the Ultra Plinian type, and it resulted in an estimated high eruption column which reached the stratosphere. In addition, the magma underlying the volcano came into contact with the shallow marine embayment, resulting in violent phreatomagmatic blasts.

The eruption also generated high tsunamis that devastated the northern coastline of Crete, away. The tsunami affected coastal towns such as Amnisos, where building walls were knocked out of alignment. On the island of Anafi, to the east, ash layers deep have been found, as well as pumice layers on slopes above sea level.

Elsewhere in the Mediterranean are pumice deposits that could have been sent by the Thera eruption. Ash layers in cores drilled from the seabed and from lakes in Turkey show that the heaviest ashfall was towards the east and northeast of Santorini. The ash found on Crete is now known to have been from a precursory phase of the eruption, some weeks or months before the main eruptive phases, and it would have had little impact on the island. Santorini ash deposits were at one time claimed to have been found in the Nile delta, but this is now known to be a misidentification.

Eruption dating

The Minoan eruption is an important marker horizon for the Bronze Age chronology of the Eastern Mediterranean realm. It provides a fixed point for aligning the entire chronology of the second millennium BCE in the Aegean, as evidence of the eruption is found throughout the region. Ten Minoan Linear A inscriptions have been found in the destruction layer at Thera, 5 vases, 2 ostraka, and 3 clay tablet fragments, the inscriptions are dated to Middle Minoan III/Late Minoan I, which is currently placed at circa 1600 BCE. Despite the evidence, the exact date of the eruption has been difficult to determine. Some archaeologists supported a 17th century BCE date, and others on historical grounds, a date of approximately 1500 BCE.

Many archaeologists considered the eruption to have occurred sometime between 1570 and 1500 BCE based on written records from Egypt and pottery found in excavations, or specifically 1530–1500 BCE. Radiocarbon dates, including analysis of an olive branch buried beneath a lava flow from the volcano that gave a date between 1627 BCE and 1600 BCE (95% credible interval), suggested an eruption date more than a century earlier than proposed by archaeologists who supported a date close to 1500 BCE. Thus, the radiocarbon dates and the archaeological dates were in substantial disagreement. Later on, it was suggested that there may have been regional variations in the calibration curve which might alter a date by up to 20 years. Various recalibrations in the years after moved the posterior probability to around 1617 to 1601 (68.3% credible interval), pointing out that "a date for the Thera eruption after c. 1543/1538 BCE remains improbable," and later to "~1606–1589 BCE (68.3% hpd interval), ~1609–1560 BCE (95.4% hpd interval)" after combining radiocarbon data with stratigraphic data. This would place it during the Second Intermediate Period of Egypt and time of the Hyksos.

Meanwhile, the olive branch dating was reevaluated in 2021, noting a bimodality of the probability distribution for the eruption date, with 62.5% probability assigned to the 1625–1600 BCE range and further 5.8% probability to 1574–1567 BCE. Also in 2021, a tsunami deposit from Letoon was dated, also by carbon-14, to after 1633 BCE but before 1345 BCE. Concurrently, another study reported the finding of skeletons of a young man and a dog in Late Bronze Age site near Çeşme, which were dubbed the first victims of the Thera eruption who have ever been unearthed. They were victims of the tsunami inundations that took place in that site after the eruption, and the researchers, based on accurate calibrated radiocarbon datings, conclude that Thera eruption happened no earlier than 1612 BCE.Yirka, Bob, (December 29, 2021)
"Skeleton of young man killed by ancient tsunami found on Turkish coast"
in Phys.org.

In 2012, Felix Höflmayer argued that archaeological evidence could be consistent with a date as early as 1570 BCE, reducing the discrepancy to around 50 years. He reviewed the various archaeological and technical dating results to conclude:
"(1) Short-Lived Samples from Akrotiri (Thera)...resulting in a date between 1664 and 1651 cal BCE (20.1% probability) or between 1642 and 1616 cal BCE (48.1% probability);
(2) (Branch of an Olive Tree) A wiggle-match for these 4 dates based on the published results indicates a date between 1621 and 1605 cal BCE (68.2% probability);
(3) (Palaikastro Tsunami Deposits) The result for this comes down to a possible date between 1657 and 1546 BCE (68.2% probability), in agreement with the data from the settlement of Akrotiri, the olive tree, and the sequence of Aegina Kolonna....:
(4) Cypriot White Slip pottery ..... provides no convincing argument against an eruption date of ~1600 BCE or shortly before."

Conversely, the radiocarbon dates have been argued to be inaccurate on scientific grounds. That argument has been made, in particular, by Malcolm H. Wiener. The primary problem is that ¹⁴C-deficient carbon, sourced from the environment, might easily have affected the radiocarbon dates. Sturt W. Manning rejects that view and states that a volcanic carbon dioxide effect does not apply to the dates of Thera eruption.

Relative chronology

Archaeologists developed the Late Bronze Age chronologies of eastern Mediterranean cultures by analysing the origin of artifacts (for example, items from Crete, mainland Greece, Cyprus or Canaan) found in each archaeological layer. If an artifact's origin can be accurately dated, it gives a reference date for the layer in which it is found. If the Thera eruption could be associated with a given layer of Cretan (or other) culture, chronologists could use the date of that layer to date the eruption itself. Since Thera's culture at the time of destruction was similar to the Late Minoan IA (LMIA) culture on Crete, LMIA is the baseline to establish chronology elsewhere. The eruption also aligns with Late Cycladic I (LCI) and Late Helladic I (LHI) cultures, but predates Peloponnesian LHI. Archeological digs on Akrotiri have also yielded fragments of nine Syro-Palestinian Middle Bronze II (MBII) gypsum vessels.

The Aegean prehistorians felt so confident about their calculations that they rejected early radiocarbon dates in the 1970s for LMI/LCI Thera, as radiocarbon suggested a date about a century earlier than the traditional dates.

Pumice, several hundred large pieces, found in a palace workshop of Tuthmosis III (1479 – 1425 BCE) at Tell el Dab'a in Egypt that matches the composition of the Thera eruption has been dated to 1540 BCE, closer to the traditionally-accepted date of Thera's eruption. This pumice has been contentious since the 1990s, as it represents the most prominent supported date to differ from the old chronology. More recent research has questioned the radiocarbon dating.

Ice cores and tree rings

Greenland ice cores were believed to be evidence of a large volcanic eruption in 1642 ± 5 BCE, which was suggested as being associated with Santorini. However, volcanic ash retrieved from an ice core did not match the expected Santorini fingerprint. The late Holocene eruption of Mount Aniakchak, a volcano in Alaska, is now considered to be the source of the minute shards of volcanic glass in the Greenland ice core. McAneney and Baillie argue that there is a chronological error in the Greenland ice core dates with ice core dates being 14 years too old, concluding Aniakchak's eruption occurred actually in 1627 BCE.

Another method that has been used to establish the date of eruption is tree-ring dating. Tree-ring data has shown that a large event interfering with normal tree growth in North America occurred during 1629–1628 (±65 years) BCE. Evidence of a climatic event around 1628 BCE has been found in studies of growth depression of European oaks in Ireland and of Scotch pines in Sweden. Bristlecone pine frost rings also indicate a date of 1627 BCE, but McAneney and Baillie reaffirm that the eruption of Mount Aniakchak, and not Thera, may have been the cause of the climatic upset evidenced by northern hemisphere tree-rings around 1627 BCE.

A 2010 study has used radiocarbon levels in bristlecone pines and Irish oak dated from 1700 BCE to 1500 BCE to develop a new calibration curve which is more accurate for this period. It results in the Thera eruption being dated to between 1600 and 1525, a time period which overlaps with the 1570–1500 date range from the archaeological evidence. Procedural changes in how ice cores are interpreted would bring that data more in line with the dendrochronological numbers. Another study that has used the patterns of carbon-14 captured in the tree rings from Gordion and bristlecone pines in the North America found the signs of the eruption in the years around 1560 BCE.

A 2022 study using tree-ring and ice-core dating also ruled out the 1628 BCE ice core event as being the Thera eruption, confirming it is the result of the eruption of the Alaskan volcano Mount Aniakchak. The study results narrowed the possible dates of eruption in Thera to 1611 BCE, 1562–1555 BCE, and 1538 BCE.

Climatic effects

Hydrogeologist Philip LaMoreaux asserted in 1995 that the eruption caused significant climatic changes in the eastern Mediterranean region, Aegean Sea and much of the Northern Hemisphere, but that was rebutted by volcanologist David Pyle a year later.

Historical impact

Minoan sites

The eruption devastated the nearby Minoan settlement at Akrotiri on Santorini, which was entombed in a layer of pumice. It is believed that the eruption also severely affected the Minoan population on Crete, but the extent of the impact is debated. Early hypotheses proposed that ashfall from Thera on the eastern half of Crete choked off plant life, causing starvation of the local population. After more thorough field examinations, the hypothesis has lost credibility, as it has been determined that no more than of ash fell anywhere on Crete. Other hypotheses have been proposed based on archaeological evidence found on Crete indicating that a tsunami, likely associated with the eruption, impacted the coastal areas of Crete and may have devastated the Minoan coastal settlements.B. Molloy, F. McCoy, R. Megarry and D. Govantes-Edwards, M. Pavlacky. 2014. 'Tephra, tsunamis and chronology at Priniatikos Pyrgos' in B. Molloy and C. Duckworth (eds) A Cretan Landscape through Time: Priniatikos Pyrgos and Environs. Oxford: BAR Another hypothesis is that much of the damage done to Minoan sites resulted from a large earthquake and the fires it caused, which preceded the Thera eruption.

Significant Minoan remains have been found above the Thera ash layer and tsunami level dating from the Late Minoan I era, and it is unclear whether the effects of the ash and tsunami were enough to trigger the downfall of the Minoan civilization. Some sites were abandoned or settlement systems significantly interrupted in the immediate aftermath of the eruption. Some archaeologists speculate that the eruption caused a crisis in Minoan Crete, opening it to Mycenaean influence or even conquest.

Chinese records

A volcanic winter from an eruption in the late 17th century BCE has been claimed by some researchers to correlate with entries in later Chinese records documenting the collapse of the semi-legendary Xia dynasty in China. According to the '' Bamboo Annals'', the collapse of the dynasty and the rise of the Shang dynasty, approximately dated to 1618 BCE, were accompanied by "yellow fog, a dim sun, then three suns, frost in July, famine, and the withering of all five cereals".

Effect on Egyptian history

Apocalyptic rainstorms, which devastated much of Egypt, and were described on the Tempest Stele of Ahmose I, have been attributed to short-term climatic changes caused by the Theran eruption. The dates and regnal dates of Ahmose I are in some dispute with Egyptologists (leaving aside alternate chronologies). Proposed reigns range from 1570–1546 BC to 1539–1514 BC. A radiocarbon dating of his mummy produced a mean value of 1557 BC. In any case this would only provide an overlap with the later estimates of eruption date.

Alternatively, if the eruption occurred in the Second Intermediate Period, the absence of Egyptian records of the eruption could be caused by the general disorder in Egypt around that time.

While it has been argued that the damage attributed to these storms may have been caused by an earthquake following the Thera eruption, it has also been suggested that it was caused during a war with the Hyksos, and the storm reference is merely a metaphor for chaos upon which the Pharaoh was attempting to impose order. Documents such as Hatshepsut's Speos Artemidos depict storms, but are clearly figurative, not literal. Research indicates that the Speos Artemidos stele is a reference to her overcoming the powers of chaos and darkness.

Greek traditions

The Titanomachy

The eruption of Thera and volcanic fallout may have inspired the myths of the Titanomachy in Hesiod's ''Theogony''. The Titanomachy could have picked up elements of western Anatolian folk memory, as the tale spread westward. Hesiod's lines have been compared with volcanic activity, citing Zeus's thunderbolts as volcanic lightning, the boiling earth and sea as a breach of the magma chamber, immense flame and heat as evidence of phreatic explosions, among many other descriptions.

Atlantis

Spyridon Marinatos, the discoverer of the Akrotiri archaeological site, suggested that the Minoan eruption is reflected in Plato's story of Atlantis.

Book of Exodus

Geologist Barbara J. Sivertsen seeks to establish a link between the eruption of Santorini (c. 1600 BCE) and the Exodus of the Israelites from Egypt in the Bible.

Bicameral mentality

In the controversial bicameral mentality hypothesis, Julian Jaynes has argued that the Minoan eruption was a crucial event in the development of human consciousness since the displacements that it caused led to new and important interactions among communities.

See also

* Timeline of volcanism on Earth
* Chronology of the ancient Near East

References

Further reading

*
*
*
*
*Notti, Erika, "The Theran Epigraphic Corpus of Linear A : Geographical and Chronological Implications", Pasiphae, vol. 000, no. 004, pp. 93-96, 2010
*Notti, Erika, "Writing in Late Bronze Age Thera. Further Observations on the Theran Corpus of Linear A", Pasiphae, vol. 000, no. 015, 2021 ISSN: 2037-738X
*
*

External links

Statistical analysis aims to solve Greek volcano mystery - David Nutt - Phys.org - September 20, 2022


* ttp://www.decadevolcano.net/santorini/santorini.htm Santorini Decade Volcano– Santorini's geology and volcanic history, the Minoan eruption and the legend of Atlantis.

The Thera (Santorini) Volcanic Eruption and the Absolute Chronology of the Aegean Bronze Age
– A WWW companion site to: Sturt W. Manning, ''A Test of Time: the volcano of Thera and the chronology and history of the Aegean and east Mediterranean in the mid second millennium BC''.


with photographs


– exploration of the submarine deposits and morphology of Santorini volcano

The eruption of Santorini in the Late Bronze Age
– Online doctoral thesis on the eruption, scientific analyses and its environmental effects (by David A. Sewell, 2001)

{{DEFAULTSORT:Minoan Eruption
16th century BC
17th century BC
2nd-millennium BC natural events
Ancient Aegean Sea
Ancient natural disasters
Ancient Thera
Ancient volcanic events
Events that forced the climate
Landforms of the South Aegean
Landforms of Thira (regional unit)
Megatsunamis
Minoan geography
Plinian eruptions
Tsunamis in Greece
VEI-7 eruptions
Volcanic eruptions in Greece
Volcanic tsunamis