An active margin is a type of continental margin that is tectonically active, typically characterized by the presence of a convergent plate boundary where an oceanic plate is being subducted beneath a continental plate. Active margins are associated with features such as deep ocean trenches, volcanic arcs, and high seismic activity. They contrast with passive margins, which are tectonically inactive.
Source Orme, A. R. “1.10 Tectonism, Climate, and Geomorphology.” Treatise on Geomorphology 1 (2013): 146.