A stratovolcano (also composite cone or composite volcano) is a tall, conical mountain (volcano) composed of both hardened lava and volcanic ash. The shape of these volcanoes is characteristically steep in profile because lava flows that formed them were highly viscous, and so cooled and hardened before spreading very far. Such lava tends to be high in silica. At the other end of the spectrum are shield volcanoes (such as Mauna Loa in Hawai'i), which are formed from less viscous lavas, giving them a wide base and more gently sloping profile. Many exceed a height of 2500m. Stratovolcanoes are often created by subduction of tectonic plates.
Because all volcanoes of any size have a stratified (layered) structure—that is, are built up from sequential outpourings of eruptive materials—volcanologists prefer to use the term stratovolcano for these mountains.
Mount St. Helens-a stratovolcano-the day before the May 18, 1980, eruption that removed much of the top of the mountain
Stratovolcanoes are usually about half-half lava and pyroclastic material, and the layering of these products gives them their other common name of composite volcanoes.
Stratovolcanoes are commonly found along subduction-related volcanic arcs, and the magma supply rates to stratovolcanoes are lower.
Additionally, stratovolcanoes are steep piles of ash, lava, and domes that are often rained heavily on, shaken by earthquakes, or oversteepened by intruding blobs of magma (or all of these).
Volcanoes include many conspicuous mountains of the earth, as Mt Vesuvius in Italy (4,000 ft. High), Mt Loa in Hawaii (14,000 ft), are examples of active volcanoes.
Stratovolcano is made when two plates come together and one slide under the other.
The lava from shield volcano is liquid, which flows from the carter and the sides of the volcano.
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