(Redirected from Thera eruption)
Satellite image of Thera
The 'Minoan eruption' of
Thera (
VEI = 7,
DRE = 60 km
3) was a major
catastrophic volcanic eruption around 1600 BCE. The eruption was one of the largest volcanic events on Earth in recorded
history.
[1][2][3] The eruption destroyed most of the island of Thera, along with the
Minoan towns nearby and on the coast of
Crete, contributing to the collapse of the Minoan culture.
The eruption caused significant climatic changes in the eastern
Mediterranean region,
Aegean Sea and much of the
Northern Hemisphere.
There is also evidence that the eruption caused failure of crops in
China, inspired certain
Greek myths, contributed to turmoil in
Egypt, and influenced many of the
biblical Exodus stories.
Eruption
Volcanic craters on Santorini today
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.
[4]
Immediately prior to the Minoan eruption, the walls of the caldera formed a nearly continuous ring of islands with the only entrance lying 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.
On
Santorini, there is a thick layer of white
tephra that overlies the soil clearly delineating the ground level prior to the eruption. This layer has three distinct bands that indicate the different phases of the eruption.
[5] Since no bodies have been found at the
Akrotiri site, Floyd W. McCoy, Professor of Geology and Oceanography,
University of Hawaii, notes that the local population had advanced warning of the impending eruption, leaving the island prior to its destruction. However, the thinness of the first ash layer along with the noticeable erosion of that layer by the first winter rains before the next layer was deposited, indicate that the volcano gave the local population only a few months warning.
[6]
Recent archaeological research by a team of international scientists in 2006 has revealed that the Santorini event was much larger than the original estimate of 39 km
3 of
Dense-Rock Equivalent (DRE), or total volume of material erupted from the volcano, that was published in 1991.
[7] With an estimated DRE in excess of 60 km
3,
the volume of
ejecta was up to four times what was thrown into the stratosphere by
Krakatau in
1883 CE, a well-recorded event, placing the
Volcanic Explosivity Index of the Thera eruption at approximately 7. The Thera volcanic events and subsequent ashfall probably sterilized the island, as occurred on Krakatau. Only the
Mount Tambora volcanic eruption of
1815 CE released more material into the atmosphere during historic times.
Physical consequences
The
plinian eruption resulted in an estimated to high
plume which extended into the
stratosphere. In addition, the
magma underlying the volcano came into contact with the shallow marine
embayment, resulting in a violent
steam eruption. The event also generated a to high
tsunami that devastated the north coast of
Crete, away. The tsunami impacted 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 there are pumice deposits which could have been caused by the Thera eruption.
[8] Ash layers in cores drilled from the seabed and from lakes in
Turkey, however, 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 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.
[9][10]
There were significant climatic changes during the aftermath of the eruption. Based on the observed changes to the
bristlecone pines of
California; the
bog oaks of
Ireland,
England, and
Germany, and the
grain crops of
China, it is believed that the plume from the eruption added sufficient particulates to the atmosphere to have reduced temperatures worldwide.
Dating
The Minoan eruption provides a fixed point for aligning the entire chronology of the 2nd millennium BCE in the Aegean, because evidence of the eruption is found throughout the region. Despite this evidence, the exact date of the eruption has been difficult to determine. Current estimates based on
radiocarbon dating indicate that the eruption occurred between
1630 and
1600 BCE.
[11] However, this range of dates conflicts with the previous estimate of approximately
1550 BCE based on archaeological studies utilizing
Conventional Egyptian chronology.
Archaeologists developed the Late Bronze Age chronologies of eastern
Mediterranean cultures by analyzing the origin of artifacts (for example, items from
Crete, mainland
Greece,
Cyprus or
Caanan) found in each archaeological layer.
If the artifact's origin can be accurately dated, then 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.
[12] Archeological digs on Akrotiri have also yielded fragments of nine Syro-Palestinian
Middle Bronze II (MBII)
gypsum vessels.
[13]
At one time, it was believed that data from
Greenland ice cores and
tree-ring dating, could be useful in ascertaining the exact date of the eruption. A large eruption, identified in ice cores and dated to
1644 BCE (+/- 20 years) was suspected to be Santorini. Previously, it was assumed that the ice core and tree-ring data were related. However, volcanic ash retrieved from an ice core demonstrated that this was not from Santorini, leading to the conclusion that the eruption may have occurred on another date.
[14] The late Holocene eruption of the
Mount Aniakchak, a volcano in
Alaska, is proposed as the most likely source of the minute shards of volcanic glass in the Greenland ice core.
[15]
Tree-ring data showed that a large event interfering with normal tree growth in
North America occurred in 1629-1628 BCE.
[16] Further evidence of an eruption of Thera around
1628 BCE was found in studies of growth depression of
European oaks in
Sweden.
[17]
In
2006, two research papers were published arguing that new radiocarbon analysis dated the eruption between
1627 and 1600 BCE. Samples of wood, bone, and seed collected from various locations in the Aegean, including Santorini, Crete,
Rhodes and
Turkey, were analyzed at three separate labs in
Oxford,
Vienna, Austria, and
Heidelberg, Germany in order to minimise the chance of a radiocarbon dating error. Results of the analysis indicated a broad dating for the Thera event between 1660 to 1613 BCE.
[18]
The date of the eruption of Thera was recently narrowed to between 1627-1600 BCE, with a 95% probability of accuracy, after researchers analyzed material from an
olive tree that was found buried beneath a lava flow from the volcano.
[19] Because the tree grew on the island, the results may have been affected by volcanic outgassing, which would have skewed the accuracy of the radiometric studies.
Although radiocarbon dating and tree-ring analysis indicate 1600 BCE eruption dating, archeologists believe that the date is contradicted by findings in Egyptian and Theran excavations. For example, some archeologists have found buried Egyptian and Cypriot pottery on Thera that is dated to a later period than the radiometric dates for the eruption. Since the Egyptian historical chronology has been established by numerous archeological studies, the exact date of the eruption remains controversial. If radiocarbon dating is accurate, there would be significant chronological realignment of several Eastern Mediterranean cultures.
[20][21]
Historical impact
Minoan civilization
According to several researchers, tsunamis caused by
pyroclastic flows and caldera collapse destroyed the navy, merchant vessels and ports of the
Minoans on the north side of Crete. As the Minoans were a sea power and depended on their naval and merchant ships for their livelihood, the Thera eruption caused significant economic hardship to the Minoans. Whether these effects were enough to trigger the downfall of the Minoans is under intense debate. Early research into the effect on the Minoans concluded that the ashfall from Thera on the eastern half of Crete choked off plant life, causing starvation of the local population. It was originally thought that to of ash fell on Kato Zakro, while fell on Knossos. However, after more thorough field examinations, this theory has lost credibility, as it has been determined that no more than of ash fell anywhere on Crete.
[22]
Significant Minoan remains have been found above the
Late Minoan I era Thera ash layer, implying that the Thera eruption did not cause the immediate downfall of the Minoans. The Mycenaean conquest of the Minoans occurred in Late Minoan II period, not many years after the eruption, and many archaeologists speculate that the eruption induced a crisis in Minoan civilization, which allowed the Mycenaeans to conquer them easily.
Chinese records
Some scientists correlate a volcanic winter from the Minoan eruption with Chinese records documenting the collapse of the
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".
[26]Impact on Egyptian history
There are no surviving Egyptian records of the eruption, and the absence of such records is sometimes attributed to the general disorder in Egypt around the
Second Intermediate Period. However, there are connections between the Thera eruption and the calamities of the
Admonitions of Ipuwer, a text from Lower Egypt during the
Middle Kingdom or
Second Intermediate Period.
[27]
Heavy 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.
[28][29][30] This theory is not supported by current archaeological evidence which show no pumice layers at Avaris or elsewhere in Lower Egypt during the reigns of Ahmose I and
Thutmosis III. While it has been argued that the damage from this storm 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.
[31]
There is a consensus that Egypt, being far away from areas of significant
seismic activity, would not be significantly affected by an earthquake in the
Aegean. Furthermore, other documents, such as
Hatshepsut's
Speos Armedios, depict similar storms, but are clearly speaking figuratively, not literally. Research indicates that this particular stele is just another reference to the Pharaoh overcoming the powers of chaos and darkness.
Greek traditions
The eruption of Thera and volcanic fallout inspired myths of the
Titanomachy in
Hesiod's ''
Theogony''. The background of the Titanomachy is known to derive from the
Kumarbi cycle, a
Bronze Age Hurrian epic from the Lake Van region. However, the Titanomachy itself 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' 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.
[32]
Biblical traditions
Some researchers have claimed that some of the
ten plagues resulted from the eruption of Thera; however, the presumed dates of the events of Exodus, approximately
1450 BCE is almost 150 years after the radiometric date of the eruption.
[33] According to the Bible, Egypt was beset by such misfortunes as the transforming of their water supply to blood, the infestations of frogs, gnats, and flies, darkness, and violent hail. These effects are compatible with the catastrophic eruption of a volcano in different ways. While the "blood" in the water could have been
red tide which is poisonous to human beings, the frogs may have been displaced by the eruption, and their eventual death would have given rise to large numbers of scavenging insects. The darkness could have been the resulting volcanic winter, and the hail the large chunks of ejecta spewn from the volcano. The tsunami that resulted from the Thera eruption could have been the basis for the myth of the parting of the sea, when the sea receded from the shore immediately prior to the arrival of the tsunami. Shallow areas of the sea would have allowed the Israelites, under Moses, safe
passage across the Red Sea, while the ensuing tsunami devastated the Egyptian army. Exodus mentions that the Israelites were guided by a "pillar of smoke" during the day and a "pillar of fire" at night, which many scholars have speculated that it refers to volcanic activity. However, unambiguous radiometric dating of Thera eruption places it at a date significantly different from the proposed dates of the Exodus from Egypt.
[34][35][36]
More importantly though, the chronology of events as presented in Exodus drastically differs from those that would have preceded from a volcanic eruption. For example, the plague of darkness came last in Exodus. In reality, darkness caused by volcanic ash would have ''preceded'' displaced frogs, hail, or a "river of blood." These effects would only have appeared after an eruption had taken place. Further, assuming the eruption had cause any of the plagues, any sort of accompanying tsunami would have taken place months before the Israelites would arrive at the Red Sea. By that time, the waters would have recessed, blocking any sort of passage on dry land.
Panoramic view of caldera rimReferences
1. Climatic, environmental and human consequences of the largest known historic eruption: Tambora volcano (Indonesia) 1815, , Clive, Oppenheimer, Progress in Physical Geography,
2.
3. Marine Investigations of Greece's Santorini Volcanic Field, Sigurdsson H, Carey, S, Alexandri M, Vougioukalakis G, Croff K, Roman C, Sakellariou D, Anagnostou C, Rousakis G, Ioakim C, Gogou A, Ballas D, Misaridis T, & Nomikou P, , , Eos, 2006
4. Fire in the Sea, the Santorini Volcano: Natural History and the Legend of Atlantis, Friedrich, WL, , , Cambridge University Press, ,
5.
6.
7. Santorini eruption much larger than originally believed
8. Pumice on south Mediterranean - remnant of the Thera eruption?
9. Volcanic shards from Santorini (Upper Minoan ash) in the Nile Delta, Egypt, Stanley, DJ & Sheng, H, , , Nature,
10. Tephra from the Minoan eruption of Santorini in sediments of the Black Sea, Guichard, F ''et al.'', , , Nature, 1993
11. New research in Science: date of the largest volcanic eruption in the Bronze Age finally pinpointed
12. On the Late Helladic I of Akrotiri, Thera
13. Summary of Evidence for the Absolute Chronology of the Early Part of the Aegean Late Bronze Age Derived from Historical Egyptian Sources in: Thera and the Aegean World III, Hardy, DA (ed), Warren, PM, , , The Thera Foundation, ,
14. Volcanic ash retrieved from the GRIP ice core is not from Thera, , Douglas J., Keenan, Geochemistry Geophysics Geosystems,
15. Identification of Aniakchak (Alaska) tephra in Greenland ice core challenges the 1645 BC date for Minoan eruption of Santorini, Pearce, N. J. G., J. A. Westgate, S. J. Preece, W. J. Eastwood, and W. T. Perkins, , , Geochem. Geophys. Geosyst., 2004
16. Irish Tree Rings and an Event in 1628 BC
17. Swedish tree rings provide new evidence in support of a major, widespread environmental disruption in 1628 BC, Grudd, H, Briffa, KR, Gunnarson, BE, & Linderholm, HW, , , Geophysical Research Letters,
18. Chronology for the Aegean Late Bronze Age 1700-1400 B.C., , Sturt W, Manning, Science,
19. Santorini Eruption Radiocarbon Dated to 1627-1600 B.C., , Walter L, Friedrich, Science,
20. New Carbon Dates Support Revised History of Ancient Mediterranean, Balter, M, , , Science,
21. Ancient Crete more ancient than thought? New volcanic evidence suggests discrepancy of more than a full century
22. The Minoans and the Mycenaeans: Aegean Society in the Bronze Age, Callender, G, , , Oxford University Press, ,
23. The Volcanic Destruction of Minoan Crete, Marinatos, S, , , Antiquity, 1939
24. The great Minoan eruption of Thera volcano and the ensuing tsunami in the Greek Archipelago, Antonopoulos, J., , , Natural Hazards,
25. Impact of the Minoan tsunami of Santorini: Simulated scenarios in the eastern Mediterranean, Pareschi, MT, Favalli, M & Boschi, E, , , Geophysical Research Letters, .
26. Texts, Storms, and the Thera Eruption, Foster, KP, Ritner, RK, and Foster, BR, , , Journal of Near Eastern Studies,
27. Atlantis: The Truth Behind the Legend, , Angelos Georgiou, Galanopoulos, Bobbs-Merrill Co, ,
28. A Storm in Egypt during the Reign of Ahmose
29. 'Studies about Kamose and Ahmose', , Hans, Goedicke, David Brown Book Company, ,
30. Texts, Storms, and the Theran Eruption, Foster, KP & Ritner, RK, , , Journal of Near Eastern Studies,
31. Separate Lives: The Ahmose Tempest Stela and the Theran Eruption, , MH, Wiener, Journal of Near Eastern Studies,
32. The end of Atlantis: New light on an old legend (New Aspects of Antiquity), , John Victor, Luce, Thames & Hudson, ,
33. Geo-Physics and Human History: New Light on Plato's Atlantis and the Exodus, Bennett, JG, , , Systematics,
34. Atlantis and the Ten Plagues of Egypt: The Secret History Hidden in the Valley of the Kings, Phillips, G, , , Bear & Company, ,
35. Act of God Phillips, G
36. Worldwide environmental impacts from the eruption of Thera, LaMoreaux, PE, , , Environmental Geology,
Bibliography
★
The Minoans and the Mycenaeans: Aegean Society in the Bronze Age, Callender, G, , , Oxford University Press, ,
★
Thera in the Bronze Age, Forsyth, PY, , , Peter Lang Publishing, ,
★
Fire in the Sea, the Santorini Volcano: Natural History and the Legend of Atlantis, Friedrich, WL, , , Cambridge University Press, ,
★
Natural Knowledge in Preclassical Antiquity, Greene, MT, , , Johns Hopkins University Press, ,
★
Atlantis and the Ten Plagues of Egypt: The Secret History Hidden in the Valley of the Kings, Phillips, G, , , Bear & Company, ,
External links
★
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''.
★
Date of the largest volcanic eruption in the Bronze Age finally pinpointed Århus University press release about the olive tree of Friedrich et al. (scientific article but also reader friendly)
★
VolcanoWorld Information about the eruption with photographs
★
Thera 2006 Expedition – 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
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