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-” pre