Forearc

thumb|275x275px|Cross-section of a subduction zone and back-arc basin. The forearc is the region between the trench and the volcanic arc.

A forearc is a region in a subduction zone between an oceanic trench and the associated volcanic arc. Forearc regions are present along convergent margins and eponymously form 'in front of' the volcanic arcs that are characteristic of convergent plate margins. A back-arc region is the companion region behind the volcanic arc.