In its modern form Avachinsky volcano - a classic example of a volcanic of Somma-Vesuvius type. The volcanoes of this type are also called double, because they are composed of young cone embedded in the destroyed massive of a larger ancient volcano. The remains of the ancient volcano in the form of an arcuate ridge are called the Somme, and a ring valley between it and the new cone - atrio.

Somme of Avachinsky volcano has a diameter of more than 4 km and was formed more than 30 thousand years ago. It is destroyed and opened in the southwestern part. In the eastern part of undestroyed massive, the altitude of the edge reaches 2317 meters. The atrio between the edges is filled with ice and firn, which descend down the slopes of the volcano. The active young cone began to form about 3,800 years ago. It has a regular shape and is located in Sommer asymmetrically. Its altitude - 2740 meters, the relative height of 400 - 1000 meters. The top is crowned with a volcano crater.

Since 1737 there were about 15 volcanic eruptions of varying strength and type, of which the most powerful eruptions occurred in 1737, 1779, 1827, 1855, 1894-1895, 1928 and 1945. After 46 years of peace volcano eruption resumed on 13-26 January, 1991 . Despite the fact that the eruption was weak during its development all the main types of hazardous volcanic processes were noted (in weak form): ash falls, lava flows, hot avalanches, small mudslides, pollution of water and air, etc.

The Avachinsky volcano crater, which until 1991 was a bowl with the diameter of 400 meters and depth of 200 meters, has always shown an intense fumarolic activity. After the eruption in 1991 the crater was sealed with a lava stopper. Then fumaroles focused mainly on contact with the edge of the lava plug of the crater.

In October 2001 it was marked that Avachinsky volcano was active again. There was a small heat output (to the height of about 900 meters), lava went out through cracks and on its north-western area there formed new powerful and relatively high temperature fumaroles.