- Composite volcanoes,
also called strato volcanoes, are formed by alternating layers
of lava and rock fragments. This is the reason they are
often form impressive, snow-capped peaks which are often exceeding
2500m in height, 1000sq.km in surface, and 400km3 in volume.
- Between eruptions they are often so
quiet they seem extinct. To witness the start of a great
eruption requires luck or very careful surveillance.
- Composite volcanoes
usually erupt in an explosive way. This is usually caused
by viscous magma. When very viscous magma rises to the surface,
it usually clogs the craterpipe, and gas in the craterpipe gets locked
up. Therefore, the pressure will increase resulting in an explosive
- Although strato-volcanoes are
usually large and conical, we can distinguish different
shapes of them: concave (like Agua), pyramidal (like Stromboli), convex-concave
(like Vesuvius), helmet-shaped (like Mount Rainier), collapse caldera
(like Graciosa), nested (like El Piton in Teide), multiple summits (like
Shasta), elongated along a fissure (like Hekla).
Different Shapes of Composite Volcanoes.
are constructed along subduction zones. Examples of composite
volcanoes include Mount Hood, Mount Rainier, Mount Shasta, Mount Fugi,
Mount Mayon, and Vesuvius.