Simple map of Sete Cidades based on Neumann van Padang and others (1967). Location of submarine explosions shown by crosses.
Sete Cidades is a stratovolcano with a summit caldera. The caldera is about 3 miles (5 km) in diameter. The walls of the caldera are about 1,500 feet (500 m) high. There are two lakes in the caldera. Sete Cidades has erupted at least eight times since ca. 1444, with six of these eruptions from submarine vents west of the volcano. The eruption in 1638 formed the ephemeral islet of Sabrina. Subaerial eruptions include a large explosive event on the southwest side of the caldera in 1444 and on the west flank of the volcano, at Pico das Camarinhas, in 1713. The most recent eruption was from a submarine vent in 1880.
Sources of Information:
Moore, R.B., 1983, Preliminary geologic map of Sete Cidades volcano, Sao Miguel, Azores (1:15,000) U.S. Geological Survey Open-File Report, 83-742.
Neumann van Padang, M., Richards, A.F., Machado, F., Bravo, T., Baker, E., Le Maitre, W., 1967, Part XXI, Atlantic Ocean: Catalogue of the active volcanoes of the world, International Association of Volcanology, Rome, Italy, 128 p.
Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.