Strato- or composite volcanoes build over zones of subduction as andesitic
magmas erupt to the surface. They form continental arcs and island arcs.
Because of the explosive style of andesitic magma eruptions, the initial
eruption generates a cone of loose, solid, odd-shaped pyroclastic material
around the vent, with the characteristic steep (40o) angle of repose. The
“strato-” prefix refers to the layering within the cone, while “composite”
refers to the interlayering of two types of material, pyroclastic and lava. A
perfect example of this type of volcano is Mount Fuji in Japan.