Thera

According to current data, the last two great eruptions of Vesuvius occured in 3580 B.C.E and 79 C.E. (the latter being the eruption which buried Pompei and Herculaneum). Both Krakatoa and Thera have a Volcanic Explosivity Index or VEI of 6 which rates them as “colossal” with a plume height over 25 km and a displacement volume of between 10 and 100 ks km. Eruptions of this size occur only once every few hundred years on earth. Although the dating of pottery supports the fifteenth century time frame for the Thera eruption, dendrochronology and radiocarbon dating supported by historical records place it at 1628/7 B.C.E.

The Eruption of Thera

 

When Krakatoa exploded on August 26, 1883, it caused widespread destruction and loss of life on the coasts of Java and Sumatra. Blast waves cracked walls and broke windows up to 160 km. away. Tidal waves, reportedly up to 36 metres high, inundated the shores of the Sunda Strait, destroying nearly 300 towns and villages, and overnight more than 35,000 people lost their lives.

J. V. Luce, The Changing Face of the Thera Problem

 

Krakatoa erupted noisily. It could be heard as much as 3,000 miles away on Rodrigues Island in the Indian Ocean. Vibrations shattered shop windows 80 miles off. The energy; released in the main explosion has been estimated to be equivalent to an explosion of 150 megatons of TNT.

 

Ships navigating the seas in the vicinity of Krakatoa reported that floating pumice in some places had formed a layer about 3 m thick. Other shops, 160 miles off, reported that they were covered with dust three days after the end of the eruption. In fact the dust cloud completely shrouded the area, so that it was dark even 257 miles away from the epicenter. The period of darkness lasted twenty-four hours in places 130 miles distant and fifty-seven hours 50 miles away. The black-out in the immediate vicinity continued for three days and was so total that not even lamp-light could penetrate it. Stunningly beautiful sunsets were observed during the winter months in both American and Europe, thanks to the suspension of fine particles of dust in the atmosphere.

Christos G. Doumas, Thera - Pompeii of the Ancient Aegean, p. 141

 

Two titanic volcanic explosions occurred in the Mediterranean in the fifteenth century BC, one on Mount Vesuvius and the other on the island of Thera near Crete. Each dwarfed the great explosion of the Krakatoa volcano in 1883.

Robert Jastrow, Hero or Heretic? Science Digest, Sep/Oct '80

 

Descriptions of the Krakatoa explosion convey a sense of the horror that must have gripped the people who witnessed the earlier and more violent eruptions in the Mediterranean:
- A tremendous roar, heard over two thousand miles away
- vibrations of the atmosphere circling the earth
- ninety-foot waves breaking with devastating force
- burning ashes raining down, blistering and killing people

Robert Jastrow, Hero or Heretic? Science Digest, Sep/Oct ‘80

 

Estimates of the volume of material displaced by the Thera eruption indicated an intensity five or six times as great as that of Krakatoa.

Dr. Floyd McCoy, in Ground Truth, Earthwatch Research Report

 

7 cubic miles (30 cubic km) of rhyodacite magma was erupted. The plinian column during the initial phase of the eruption was about 23 miles (36 km) high.

Santorini, Greece

 

The caldera (or crater) created by this eruption of the the Stroggili volcano on Thera (now known as Santorini) is said to have measured as much as 83 square kilometers in area. It presently extends down as much as 480 meters below sea level inside of the wall of cliffs which ring it and which themselves rise up as much as 300 meters above sea level.

Encyclopaedia Britannica