ok let me give you some information on the eruptions that followed the big one that erased the Minoan culture off the map.
From 197 bc, we have 11 eruptions. We have photos from the eruption of 1935-1928 and 1950.
The eruption of 1950 shook the island quite well overnight sprung a new island, Nea Kameni, and destroyed several buildings because of earthquakes that followed the explosion. The explosion was underwater, and because of that there were not serious problems. Somehow the island benefited from this explosion as most older buildings collapsed and they had to rebuild with new buildings, which boomed the tourism from then on. This eruption lasted less than one month.
[link to www.geo.auth.gr
[link to www.geo.auth.gr
We also have accounts from previous eruptions like the one on 23 May 1707. Father Tarillon, a jesuit missioner who has installed in Santorini reports to his superiors.
"Five days ago, on May 18, two small earthquakes were felt on the island. But no one cared. It seems that from this day on a small island started to emerge from the depths of the sea.
Anyway, in the next morning the sailors saw the peaks of island coming out and thought it was the remains of a shipwreck. So they took the boats and went to see the wreck and to search for survivors. But instead of wreck they fell on rocks. Fearful the Santorinioi quickly returned to the island and narrated the strange phenomenon that saw.
Panic spread throughout the island of Santorini. The barmy residents lived moments of anguish waiting for explosions and sinking. But three days passed and nothing to disaster happened.
Then some brave Santorinioi decided to go near and see up close what happens. They sailed around with their boats carefully studying everything. Then, seeing how there was no danger, they went even closer and stepped on the new land. Out of curiosity they stepped from rock to rock and found out how soft these rocks were which were cut like bread. Indeed some said that the color, composition and even taste, was like barley bread. Their best finding though was numerous oysters, which stuck on the rocks and were very rare in Santorini. So we all set about picking as many as they could.
"Suddenly they felt swaying rocks and all, to tremble beneath their feet. Terrified, they left the little island and jumped in their boats. This vibration was simply a slight movement of the island, which was growing.
Within few days it began developing twelve meters wide and six high.
But the island was not growing properly or evenly. Many times one part lifted and another sank. One day I watched a huge rock rising in the middle of the island for about 15 feet. I closely watched it for four days. Suddenly it sank in the sea and perished.
But other rocks, came out and sank and again came out of the water and became more stable. All of these quakes were shaking the island of Mikri Kameni (Little Burned). A deep crack appeared first in the top.
"Meanwhile, the sea constantly changed colors. From bright green to reddish-pale. A heavy smell rose from the depths of the waters.
"On July 16 for the first time smoke appeared from the new island. But not from the visible part. The smoke blows black rosary rocks that had emerged at the point where the sea was by then bottomless. 'From these rocks formed two separate little islands. One was called 'Aspronisi' (white island) and the other Mavronisi (black island) by their color. Soon, however, they joined together and the black rocks became the center of the island. Dense and whitish smoke was rising constantly.
"On the night of 19 to 20 July, at the center of this smoke flames sprang. The people at Skaros panicked. The houses were built within half a league, and the castle hung suspended on vertical cliffs where the sea ended. I waited to blown up from time to time by the fire spreading out its tentacles certainly, and in the depths of their rock. So, they decided to quit the castle, and their belongings to go to another island or another corner of the island.
"The Turks who were in those days on the island to collect taxes were frighten to death. Frantic of the sight of flames rise from the depths of the sea asked the people to begin prayers to God and invited the children to go out into the streets and shout "Lord have mercy." Because, they said, the children were pure and their supplication, could calm down the divine wrath.
[link to skinious.blogspot.com
This was the creation of Megali Kameni, a small island at the Santorini Caldera.