Active stratovolcano. Artwork showing ash rising from the crater of an active stratovolcano. A stratovolcano is a type of volcano that has many layers, or strata, that are formed by successive volcanic eruptions. The layers build up to form the cone shape seen here. The eruptions are fuelled by lava rising up a central vent to the crater on the peak. The lava rises from a magma chamber deep below the volcano. At the moment, this volcano is quietly active but not erupting, and ice and snow have formed on its peak. An example of a snow-capped stratovolcano is Mount St Helens, in Washington State, USA.