How do volcanoes form at constructive plate margins?
At constructive boundaries, magma from the earth's interior
rises to the surface and forms mostly fissure volcanoes, but a few
other tyopes as well, and forms new crust which pushes away older
crust
At destructive boundaries, in a process called subduction, an
oceanic plate slides into the earth's mantle, where it melts. The
molten roick then rises to the surface and fornms a chain of
volcanoes, mostly stratovolcanoes, but a few of other types as
well