The 1939-1941 eruption of Nea Kameni, Santorini
Map of the lavas from the 1939-41 eruption on Nea Kameni (from G.E. Vougioukalakis, 2005)
The craters on top of Georgios lava dome and the 1941 Niki lava dome in the background
Historic photo of the activity of the Fouque lava dome (1940)
The eruption was preceded by changes of the water color and an increase of the waters in the bay of Agios Georgios chapel in early May. Seismic and geodetic monitoring was not available at that timr, but it was observed that the coastline was subsiding, suggesting a strong uplift of Nea Kameni.
Historic photo showing small explosive activity from the Ktenas lava dome (1939)
A first submarine explosion took place on 20 August, and a small lava dome appeared which was called Triton, after the fish-tailed sea god, son of Poseison, God of the Seas.
In late September, the activity shifted a few 100 m to the NE, where a new lava dome and some viscous lava flows were erupted, named Ktenas (a Greek volcanologist who had studied the 1925-28 eruption).
Lava flows from the Ktenas lava dome filled the little harbor of Agios Georgios and covered the Triton lava dome.
In mid November, a new vent opened further to the NE. Until July 1940, a new lava dome formed in this area. It was called Fouqué lava dome after the famous French geologist who had been working on the island during the 1866-1870 eruption and produced the geological map of Santorini, which is the base of the current geological maps until today.
In July 1940, 2 new vents appeared south of the Fouque lava dome, and 2 new lava domes formed there, called Smith and Reck lava domes (after an American and a German volcanologist, respectively, who had studied the 1925 eruptions).
The lava flows from the Smith and Reck lava domes covered the western slope of Nea Kameni and almost reached the sea.
Intermittent explosive activity accompanied the mainly effusive phases of the eruption. Maximum heights of ash columns were reported as 1200 meters.
The eruption resumed in late 1940, with 2 preatic explosions from the crater of the 1866 Georgios lava cone, excavating the 2 roughlz 50 m diameter craters still visible today at its top. No lava extrustion followed these explosions.
New lava appeared at the end of November 1940 from a new vent about 100 m to the east, and created the steep-sided Niki lava dome with 3 large viscous flow to the east, which came close to the sea. The dome was ames Niki = 'victory' in honor of the victories of the Greek Army in front of Albania.
The activity ended in July 1941.
Blue Volcanoes - a great guide to Santorini's volcano, available widely on Santorini (new edition 2005)