Environmental Effects Of The Thera Eruption example essay topic

What were the cultural and environmental effects of the Bronze Age explosive volcanic eruption of Thera, Greece? "And, that high heaven might be no safer than the earth, They say that the Giants essayed the very throne of heaven, Piling huge mountains, one on another, clear up to the stars. Then the Almighty Father hurled his thunderbolts, Shattered Olympus, and dashed Pelion down from underlying Ossa. When those dread bodies lay o'erwhelmed by their own bulk, They say that Mother Earth, drenched with their streaming blood, Informed that warm gore anew with life, and, That some trace of her former offspring might remain, She gave it human form". - Ovid's Metamorphoses No written records exist of the Minoan eruption of the Bronze Era.

According to Greek legends, the Destruction of Atlantis or the Battle of the Titans occurred in Seventeenth century B.C. Admittedly, it is temping to believe idealistic and attractive myths, but modern science can explain it much more logically. Scientists can accurately extrapolate what occurred around 1600 B.C. There was an enormous volcanic explosion on Thera (now called Santorini), which is now commonly referred to as the Minoan eruption. Today we can investigate the scientific, environmental, and cultural aspects of the eruption with modern knowledge of volcanology, volcanic ash deposits, archaeological excavations, and ancient Greek legends of Atlantis. Thera is located in the Hellenic arc, a line of islands stretching from Greece to Turkey that separates the Aegean Sea from the Mediterranean. The region owes its volcanic nature to the plate collisions between the African and European plates (Fig 1). When under thrusting occurs, in regions known as subduction zones, conditions are ripe for the generation of magmas by melting deep in the Earth.

The eruption of Thera around 1600 B.C. was the largest of its kind in the region since the great Campania n eruption in the Phlegrean Fields in Italy 35,000 years ago (Fielder and Wilson, 1975). To investigate the science of the explosion, it is useful to classify the type of volcano that Thera was and is. There are several types of volcanoes using eruptive habits and form as a means of classification: Icelandic, Hawaiian, Strombolian, Vulcanian, and Plinian. Icelandic volcanic eruptions usually involve the pouring out of hot, fluid molten lava from lengthy fissures that are sometimes as long as 25 kilometers (Decker, 1991). The gases dissolved in the erupting magma boil out at surface pressures, forming spectacular lava fountains along the erupting fissures. Hawaiian volcanoes also erupt from fissures at the mountains's umm its and rift zones.

They are similar to Icelandic volcanoes, but tend to form sloping dome mountains instead of lava plateaus. Strombolian volcanoes have constant small explosions of bursting gas, which throws a shower of clots of pasty, incandescent lava into the air. These volcanoes are usually steep, conical mountains because they erupt from a pipe like conduit rather than a fissure. Vulcanian volcanoes have stronger explosive eruptions that form dark ash clouds mainly composed of steam, other gases, and solid fragments of material. The ash clouds from these eruptions expand into cauliflower-shaped lobes in the sky.

Plinian volcanoes have the most explosive eruptions. The explosions are sustained by the jetting of volcanic ash into a high cloud. Thick blankets of ash and pumice fall to the ground downwind, while fine ash and volcanic gases are injected into the stratosphere (Fisher and Heiken, 1997). Plinian eruption causes circular basins at the summits of volcanoes known as calderas. The island of Santorini lies around a calderas (Fig. 2), so the volcano that shook the region can be classified as a Plinian volcano. Plinian eruptions are not just single explosions, but rather sustained, highly destructive eruptions with no combustion.

But Icelandic and Hawaiian volcanoes can also form calderas. So like all generalities, classification of eruption and volcano types can only be taken so far. Naming the types of volcanoes, while helpful in understanding them, is only the beginning. While there are several different types of eruptions and structures for volcanoes, the basic principle of their activity is universal.

Volcanoes erupt for two fundamental reasons. First, magma deep in the Earth is generally less dense than the solid rocks surrounding and overlying it. Second, it tends to rise toward the surface of the crust from the buoyant force of gravity. As a result of reaching the surface, dissolved gases boil out of the molten rock and the force of that expansion propels lava or lava fragments from the vent of the volcano (Fielder and Wilson, 1975). The eruption that shattered Thera was in all likelihood a very explosive one. If the gas content is high and the magma is thick and viscous, a sudden release of the pressure allows the gases to boil explosively from the magma.

The eruption on Thera can be explained by scientific surveys of modern volcanoes, but the magnitude of the great explosion on the environment and culture of that time can only be investigated through the past. The environmental effects of the Thera eruption were without a doubt global in extent. From observations of other more recent large-scale eruptions, scientists know that volcanoes can cause short-term changes in the global climate. Scientists have used the growth rings and radiocarbon dating of ancient trees in California, Nevada, and Ireland to indicate that there was a stunting of tree growth around 1626 to 1628 B.C. (Fisher and Heiken, 1997). This can be explained by a sudden change in climate patterns due to the Thera eruption. In addition, ice cores taken from Greenland contain the fallout of impurities present in the atmosphere at that time.

A volcanic sulfuric acid layer occurs at a depth of 1227.5 m and has been dated to about 1645 B.C., which is around the same time as the growth ring dating (Decker, 1991). While it is not completely confirmed that the layer of ice tested dates from the Minoan eruption, the data seems to match up with our investigation. An eruption the size of the Minoan event must have created complete chaos with the environment of the Eastern Mediterranean. The explosion sent ash flying 36 km high into the atmosphere. The fine mist of volcanic pollutants in the stratosphere created a blanket against incoming solar rays and radiation. It can be related to the asteroid impact that destroyed the dinosaurs, but on a much, much smaller scale.

The fallout probably destroyed or damaged the crops of Thera's neighbors. The total ash and pumice fallout from the eruption was equivalent to about 20 cubic miles of rock. In addition to the tremendous amount of fallout, vast quantities of hot ash flowed from the volcano and into the Aegean Sea. The seawater was displaced and huge tsunamis were created. The total production of magma during the eruption is estimated as forty times the quantity produced by Mount St. Helens in 1980. The environmental effects were enormous and the ancient Mediterranean civilizations were all involved in the consequences.

The cultural effects of the Minoan eruption can be seen through the ancient books and texts, and through perfectly preserved towns such as the Minoan city of Akroteri. Akroteri was a major seaport and thriving commercial center located on Thera, between the island of Crete and the Greek mainland. Excavations of Akroteri conducted by the Greek archaeologist Spyridon Marinates uncovered a wealthy and artistic city. The city appears to have been evacuated before the eruption that destroyed most of Thera occurred. Precious weapons, metals, and tools were carried away and jars of seed grain were left behind to plant the fields again when the people of the town returned (Decker, 1991).

But they never did return to the doomed city. The people had time to evacuate because several years before the great eruption, Thera probably exhibited signs of activity, including frequent and even severe earthquakes, gas emissions, and small explosions. If Thera was Atlantis, as the ancient Greeks believed, then the people of that mythical civilization escaped the volcano sometime before the great eruption. Originally it was thought that the explosion of Thera directly caused Crete's downfall by destroying the island with ash fall and tsunamis, but some believe that is not the case. Some dating by scientists has shown that the palaces on Crete were destroyed 200 years after the dating of the eruption. Also, there is little evidence of flood damage on the island's ports.

At Moloch os on Crete the ash layer is clearly beneath the Lower Minoan pottery level (Decker, 1991). This is strong evidence that the eruption predated the destruction on Crete. In conclusion of the cultural effects on the Minoan culture, it is easy to be led to believe that the eruption wiped out a great, seafaring Bronze Age civilization like the tales of Atlantis. But certainly, the present state of knowledge about the Thera eruption shows that is now true. It appears that the eruption and destruction of palaces on Crete being within decades of one another is only a coincidence. There can be speculation about the fact that the volcanic event could have weakened the Minoans on Crete for attack, but this cannot be proven as of today.

The Thera eruption, regardless of whether it directly or indirectly caused the decline of the Minoan civilization, can be considered to be one of the most influential volcanic eruptions ever to have taken place in human history. Modern science has used a variety of ways to unlock the past without any scientific direct accounts to use. Legends and myths are entertaining to the soul, but analysis of ash deposits, archeological digs, and observations of present day volcanoes reveal the real truth about the great Thera eruption of the Bronze Age. Today, scholars can still debate the cultural effects, but the environmental effects and physical mechanics of the eruption have been proven by science and its methods. It was a catastrophic event that has and will continue to echo through time. Hopefully, with time, the echo will only get louder and clearer..