Where are the largest volumes of andesite lava usually extruded?

Andesite lava is predominantly extruded in subduction zone environments, where oceanic lithosphere is subducting beneath continental crust. This process occurs because the subduction of the denser oceanic plate leads to increased magma generation due to the melting of mantle material and the addition of volatiles like water. The composition of this magma is typically andesitic, which has a higher silica content than basaltic magma.

These volcanic arcs, which form parallel to subduction zones, are characterized by explosive eruptions typical of andesite because the higher viscosity of andesitic magma traps gases more effectively than basaltic types. This geological setting is crucial for the formation of mountain ranges and volcanic activity associated with subduction zones. Thus, the presence of andesite lava is strongly linked to the tectonic processes occurring at the interface of oceanic and continental plates.