Santorini's Volcano
Recent volcanism
In 1707 an undersea volcano breached the sea surface, forming the current centre of activity at Nea Kameni in the centre of the lagoon, and eruptions centred on it continue — the twentieth century saw three such, the last in 1950. Santorini was also struck by a devastating earthquake in 1956. Although the volcano is quiescent at the present time, at the current active crater (there are several former craters on Nea Kameni), steam and carbon dioxide are given off.
Santorini has erupted many times, with varying degrees of explosivity. There have been at least twelve large explosive eruptions, of which at least four were caldera-forming. The most famous eruption is the Minoan eruption, detailed below. Eruptive products range frombasalt all the way to rhyolite, and the rhyolitic products are associated with the most explosive eruptions.
The earliest eruptions, many of which were submarine, were on the Akrotiri Peninsula, and active between 650,000 and 550,000 years ago. These are geochemically distinct from the later volcanism, as they contain amphiboles.
Over the past 360,000 years there have been two major cycles, each culminating with two caldera-forming eruptions. The cycles end when the magma evolves to a rhyolitic composition, causing the most explosive eruptions. In between the caldera-forming eruptions are a series of sub-cycles. Lava flows and small explosive eruptions build up cones, which are thought to impede the flow of magma to the surface. This allows the formation of large magma chambers, in which the magma can evolve to more silicic compositions. Once this happens, a large explosive eruption destroys the cone. The Kameni islands in the centre of the lagoon are the most recent example of a cone built by this volcano, with much of them hidden beneath the water.
Minoan eruption
Physical eruption
The devastating volcanic eruption of Thera has become the most famous single event in the Aegean before the fall of Troy. It may have been one of the largest volcanic eruptions on Earth in the last few thousand years, with an estimated 7 on the VEI (volcanic explosivity index). The violent eruption was centred on a small island just north of the existing island of Nea Kameni in the centre of the caldera; the caldera itself was formed several hundred thousand years ago by the collapse of the centre of a circular island, caused by the emptying of the magma chamber during an eruption. It has been filled several times by ignimbrite since then, and the process repeated itself, most recently 21,000 years ago. The northern part of the caldera was refilled by the volcano, then collapsing once more during the Minoan eruption. Before the Minoan eruption, the caldera formed a nearly continuous ring with the only entrance between the tiny island of Aspronisi and Thera; the eruption destroyed the sections of the ring between Aspronisi and Therasia, and between Therasia and Thera, creating two new channels.
On Santorini, a deposit of white tephra thrown from the eruption is found lying up to 60 m (200 ft) thick, overlying the soil marking the ground level before the eruption, and forming a layer divided into three fairly distinct bands indicating different phases of the eruption. New archaeological discoveries by a team of international scientists, in 2006, have revealed that the Santorini event was much more massive than previously thought; it expelled 61 cubic kilometres (15 cu mi) of magma and rock into the Earth's atmosphere, compared to previous estimates of only 39 cubic kilometres (9.4 cu mi) in 1991, producing an estimated 100 cubic kilometres (24 cu mi) of tephra. Only theMount Tambora volcanic eruption of 1815, the 181 AD eruption of Lake Taupo, and possibly Baekdu Mountain's 969 AD eruption have released more material into the atmosphere during the past 5,000 years.
Speculation on an Exodus connection
In The Parting of the Sea: How Volcanoes, Earthquakes, and Plagues Shaped the Exodus Story, geologist Barbara J. Sivertsen seeks to establish a link between the eruption of Santorini (c. 1600 BC) and the Exodus of the Israelites from Egypt in the Bible.
A 2006 documentary film by Simcha Jacobovici, The Exodus Decoded, postulates that the eruption of the Santorini Island volcano (referred to as c. 1500 BC) caused all thebiblical plagues described against Egypt. The documentary presents this date as corresponding to the time of the Biblical Moses. The film asserts that the Hyksos were the Israelites and that some of them may have originally been from Mycenae. The film also suggests that these original Mycenaean Israelites fled Egypt (which they had in fact ruled for some time) after the eruption, and went back to Mycenae. The Pharaoh of the Exodus is identified with Ahmose I. Rather than crossing the Red Sea, Jacobovici argues a marshy area in northern Egypt known as the Reed Sea would have been alternately drained and flooded by tsunamis caused by the caldera collapse, and could have beencrossed during the Exodus.
Jacobovici's assertions in The Exodus Decoded have been extensively criticized by religious and other scholars. In a 2013 book on this connection, Thera and the Exodus,Riaan Booysen supports Jacobovici's theory through a comprehensive study of ancient Greek legends of floods in the Mediterranean Sea and Egyptian records attesting to floods in their country, as well as the interpretation of legendary names associated with various Egyptian kings (pharaohs) of that period. He identifies the pharaoh of the Exodus asAmenhotep III and the biblical Moses as Crown Prince Thutmose, Amenhotep’s first-born son and heir to his throne.
.svg)
Speculation on an Atlantis connection
Archaeological, seismological, and vulcanological evidence has been presented linking the Atlantis myth to Santorini. Speculation suggesting that Thera/Santorini was the inspiration for Plato's Atlantis began with the excavation of Akrotiri in the 1960s, and gained increased currency as reconstructions of the island's pre-eruption shape and landscape frescos located under the ash both strongly resembled Plato's description. The possibility has been more recently popularized by television documentaries such as The History Channelprogramme Lost Worlds (episode "Atlantis"), the Discovery Channel's Solving History with Olly Steeds, and the BBC's Atlantis, The Evidence, which suggests that Thera is Plato's Atlantis.
Recent eruptions
Post-Minoan eruptive activity is concentrated on the Kameni islands, in the centre of the lagoon. They have been formed since the Minoan eruption, and the first of them broke the surface of the sea in 197 BC Nine subaerial eruptions are recorded in the historical record since that time, with the most recent ending in 1950. Since then the volcano has been quiescent.
Small tremors and reports of strange gaseous odours over the course of 2011 and 2012 prompted satellite radar technological analyses and these revealed the source of the symptoms; the magma chamber under the volcano was swelled by a rush of molten rock by 10 to 20 million cubic metres between January 2011 and April 2012, which also caused parts of the island’s surface to rise out of the water by a reported 8 to 14 centimetres. Scientists say that the injection of molten rock was equivalent to 20 years’ worth of regular activity.
Source: Wikipedia
I love Santorini, it is a very beautiful island.
ReplyDelete