Yantarni is a stratovolcano. It is considered an immature volcano, because it lacks a large, shallow magma chamber. It is made mostly of andesite and dacite. This volcano is ~2400 ft (730 m) high. Its volume is 3.5 cu km. Yantarni formed near a high angle fault at a site of previous activity involving magma. Its first lava flows were andesitic. They came from several different vents. The breached cone formed a debris avalanche deposit. This was followed by a directed blast and formation of a dome and pyroclastic flows. These pyroclastic flows are about 1 cu km in volume. They extend 2.5 miles (4 km) from the cone. Yantarni was not discovered until 1979. It has erupted only once. That was almost 2800 years ago.
Wood, Charles A. and Kienle, Jurgen, "Volcanoes of North America," Cambridge University Press, New York, 354 pp., 1990.
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