Almost one and a half centuries before the recorded birth of Christ in a sleepy quarter of the Aegean Sea, between the rugged coasts of present-day Greece and Turkey, lay the beautiful island of Stronghyli (Santorini), some 70 miles north of Crete.

The idyllic surroundings and peaceful lifestyle of its inhabitants was catastrophically interrupted when the 4900-foot mountain heaved, roared, then blew up in a volcanic eruption of unimaginable violence.

When the thunderous wrath of the gods ceased the central portion of the island dropped into a deep hole in the sea. The pieces that remained-called the islands of Santorini today-were buried under volcanic ash.

The explosion and its aftereffects were enough to change the course of history. Archeological evidence has long indicated that a series of catastrophic events-in fact, the cataclysm out of which Western civilization emerged-took place around the 15th century B.C. But did the Santorini eruption occur at the precise time, and was it of sufficient magnitude, to have had such enormous consequences?

In 1956 an accidental discovery was made by Prof. Angelos Galanopoulos, of the Athens Seismological Institute. On the island of Thera, one of the remnants of Santorini that had not sunk under the sea, he visited a mine from which volcanic ash is removed for use as cement. At the bottom of the mine shaft he discovered the fire-blackened ruins of a stone house. Inside were two pieces of charred wood and the teeth of a man and a woman. Radiocarbon analysis disclosed that they had died in approximately 1400 B.C. - the 15th century B.C. And the volcanic ash that covered them was 100 feet thick; the eruption that laid it down may indeed have been the greatest in history.

Just how violent was the Santorini explosion?

For comparison, scientists turn to the Krakatoa eruption in the East Indies (Indonesia) in 1883. That volcanic island cracked at its base, allowing an inrush of cold sea water, which mingled with hot lava. The irresistible pressure of expanding steam and gas blew the top off 1460-foot Krakatoa, sent a fiery column of dust 33 miles into the air and hurled rocks 50 miles.

The dust circled the earth for many months. When the eruption had spent its force, the empty shell of the volcano collapsed into a 600-foot-deep crater in the sea, creating enormously destructive tidal waves. The roar shook houses to a distance of 480 miles and was heard almost 3000 miles away.

The explosion of Santorini followed the same pattern as Krakatoa, geologists say - except that it must have been many times more violent. The aerial energy released was equivalent to the simultaneous explosion of several hundred Hiroshima type hydrogen bombs, according to Galanopoulos. It buried what remained of the island under 100 feet of burning ash. The wind spread the Santorini ash over an 80,000-square-mile area, largely to the southeast, where it still lies as a layer of the seabed, from several inches to many feet thick.

When the volcano had emptied itself, the hollowed-out mountain dropped into its magma chamber, 1200 feet below sea level, creating a vast crater or "caldera," into which the ocean poured. Tidal waves were set up, estimated to have been one mile high at the vortex. Roaring outward at 200 miles per hour, the waves smashed the coast of Crete with successive walls of water 100 feet high, engulfed the Egyptian delta less than three hours later, and had enough force left to drown the ancient port of Ugarit in Syria. These are the calculations of the Santorini explosion's physical effects. Its historical effects may have been even more profound.

Western civilization traces its aesthetic, intellectual and democratic traditions back to classical Greece. At the time of the Santorini explosion, however, Greece was inhabited by relatively unsophisticated Helladic tribes. In contrast, the Minoan civilization, centered in a dozen cities on Crete with outposts on Santorini, was already highly advanced.

The Minoans employed a sophisticated form of writing. They enjoyed a variety of sports, including boxing, wrestling and bull games in which contestants vaulted over the horns of the charging animals. They used flush toilets, air-conditioned their houses by channeling cool breezes into them and created superb vases, ornaments and wall paintings. Their ambassadors and merchant fleets ranged the oceans of the ancient world.

Late in the 15th century B.C., at the height of its strength, this brilliant civilization abruptly vanished. Excavations indicate that all of the Minoan cities were wiped out at the same time, all the great palaces destroyed, their huge building stones tossed around like matchsticks.

Until 20th century geologic discoveries, the obliteration of Minoan civilization was an intriguing mystery, attributed to revolution or invasion. However, scholars, led by Professors Dragoslav Ninkovich and Bruce C. Heezen of Columbia University's Lamont-Doherty Geological Observatory, were convinced that the destruction was caused by the eruption of Santorini- by the holocaust itself, by its aerial shock waves and by the ensuing tidal waves. The heavy fallout of volcanic ash filled Crete's fertile valleys, destroyed the crops and rendered agriculture on the island impossible for decades. Almost the entire Minoan race perished.

There were scattered survivors-those who managed to reach the high mountains, those who were on distant voyages at the time. Archeological evidence indicates that most of these people fled to western Crete, and from there northward to Mycenae on the nearby shores of Greece. Although battered by tidal waves, Greece had not suffered from the volcanic fallout, thanks to the northwest wind. The results of the Minoan migration were quickly apparent in the flowering of Mycenaean civilization, about 1400 B.C., when the written history of Greece begins.

The refugees introduced the Greeks to their alphabet, art, archery and games. They taught them to work in gold and probably helped them build the great tombs and palaces that are the glory of Mycenaean culture.

Neither the vanished civilization nor the catastrophe was forgotten. These lived on for hundreds of years in various legends, including the story of Atlantis.

According to Plato, who recorded the incident later, Solon, the Athenian lawmaker, on a visit to Egypt in 590 B.C., was told by Egyptian priests that in the ancient past "there dwelt in your land the fairest and noblest race of men which ever lived; of whom you and your whole city are but a seed or remnant. But there occurred violent earthquakes and floods, and in a single day and night of rain all your warlike men in a body sank into the earth, and the island of Atlantis disappeared beneath the sea."

Atlantis, by this account, was an island kingdom. It reputedly had an area of 800,000 square miles-too big to fit into the Mediterranean-and Plato placed it in the ocean beyond the Pillars of Hercules (the Strait of Gibraltar), thereby giving the Atlantic its name. It was destroyed, according to Plato, 9000 years before Solon's time.

Archeologists point out many factual impossibilities in Plato's account of the lost Atlantis. Galanopoulos believes that Solon simply misread the Egyptian symbol for "100" as "1000," thereby multiplying all figures tenfold. Eliminate that extra zero and the destruction took place 900 years before Solon-in the 15th century B.C, which coincides with the destruction of Santorini. Atlantis's size, then, would have been 80,000 square miles, which accords nicely with the dimensions of the eastern Mediterranean islands. Galanopoulos notes, too, that there are two promontories on the coast of Greece near Crete also called "Pillars of Hercules."

From Plato's descriptions, the plain on which the "Royal City of Atlantis" was located closely resembles the plain on Crete where the Minoan city of Phaistos stood. And the description of the part of the kingdom which was sacred to the sea god Poseidon, with its steam fissures, hot springs and concentric circular canals, "fits perfectly the features, shape and size of the island of Santorini," says Galanopoulos. "Traces of the canals and harbors are discernible even now on the floor of the caldera, or undersea crater." These and other parallels have induced at least one distinguished historian to note, "It seems that the riddle of Atlantis has finally been solved."

A second great historic consequence of the Santorini cataclysm is the effect it may have had on northern Egypt, 450 miles away, where the children of Israel labored as slaves at the time. Historians have long noted the resemblance between the Ten Plagues, as recorded in the Bible, and disasters that have accompanied volcanic eruptions. The surrounding waters may turn a rusty red, fish may be poisoned, and the accompanying meteorological disturbances frequently create whirlwinds, swamps and red rain.

The Ten Plagues produced similar phenomena. The waters of Egypt turned red as blood, killing fish and driving frogs on shore. Darkness covered the land for three days. The heavens roared and poured down a fiery volcanic hail. Strong winds brought locusts, which destroyed what crops remained. Insects, which bred in the rotting bodies and swamps, brought disease to cattle and humans. Death was so rampant as to amount to the killing of the "firstborn" of every family.

Egyptian documents confirm the disaster. "The land is utterly perished . . . the sun is veiled and shines not," says one papyrus. "O that the earth would cease from noise, and tumult be no more!" laments another. "The towns are destroyed ... no fruit nor herbs are found . . . plague is throughout the land."

Did the enslaved Israelites take advantage of the confusion and begin their epic migration to the Promised Land? As evidence, some biblical scholars cite I Kings 6:1: "And it came to pass, in the 480th year after the children of Israel were come out of the land of Egypt in the fourth year of Solomon's reign over Israel. . . ." Since Solomon reigned from 970-930 B.C., that puts the Exodus right around the time that Santorini exploded.

The Bible relates that Pharaoh pursued the Israelites and drowned in the sea with his army. Egyptian inscriptions also refer to this event. Galanopoulos attributes the disaster to the tidal waves created when the cone of Santorini dropped into the sea-which could have occurred weeks after the eruptions.
He points out that the Hebrew words yam suf can mean either "Red Sea" or "Reed Sea," and declares that many scholars believe it was the latter that the Bible refers to. He identifies the location as Sirbonis Lake, a body of brackish water in northern Sinai between the Nile and Palestine, which is separated from the Mediterranean by a narrow barrier of sand. He believes that the Israelites fled across this dry bridge, with the waters "on their right hand and on their left," during the interval when the sea was drawn back toward the Aegean, and that the Egyptians were caught in the huge returning tidal wave. The interval would have been about 20 minutes.

These theories about the Exodus stand on shakier ground than those concerning the destruction of Minoan civilization and the disappearance of Atlantis. Nevertheless, they seem to have occurred too closely together in time to be ascribed to mere chance. They fit together like parts of an incomplete jigsaw puzzle. Today scientists and historians are working hard to find the missing pieces that will prove the contention that Western civilization was born in the flame and ashes of a volcanic eruption in the Aegean, 3400 years ago.