volcanicity

adjective

of or relating to a volcano: a volcanic eruption.
discharged from or produced by volcanoes: volcanic mud.
characterized by the presence of volcanoes: a volcanic area.
suggestive of or resembling a volcano; potentially explosive; volatile: a volcanic temper.

adjective

of, relating to, produced by, or characterized by the presence of volcanoesa volcanic region
suggestive of or resembling an erupting volcanoa volcanic era
another word for extrusive (def. 2)

adj.

1774, from French volcanique (see volcano). Figurative sense of “prone to explosive activity” is attested from 1854.